> \ ■f ''nU'L M-5 -?iJi tD'bv- O'Q'BEl^mi flk/iiO/a-ibullHaiiHf.- ^Mmmm smoni)-myrm. d. Wages, 5 men and 1 boy 17 10 Coal, J ton 7 6 Oil, cotton-waste, &c 3 6 £1 8 10 equal to 9d per ton, screenings included, and the total cost, including wear and tear and all expenses, was about Is. a cube yard for breaking by the machine a stone which costs Is. IQd. per cube yard to break by hand. The amount of small stuff separated by the screen averaged about one-sixth of the whole, or twice as much as would result from hand-breaking. At Barnton, where the stone is syenite and much harder, an average of about 32 tons a day was broken by a machine of the same sort, at a cost, for wages, coal, oil, &c., of Is.' Id. per ton. Including all expensee, the total cost was about 2s. per cube yard of road material, which it would cost 3s. &d. to 4s. per cube yard to break by hand. In France a commission appointed to experiment on stone- breaking by machines found that an American machine, similar to Blake's, produced one-fifth of screenings compared with one-sixth produced by hand-breaking. There was, how- ever, less dust and more small stone in the screenings from the machine, the proportion varying with the nature of the stone. The machine broke about 22 cube yards per day, and the cost including interest, depreciation, &c., was found to be Is. Id. per cube yard, when the price paid to contractors for the same stone was 3s. 2>d, An economy of 50 per cent, was thus shown, supposing that the machine was kept in regular work, which can very rarely be realised in practice. The following particulars of the cost of stone-breaking by machines of various sorts, including all charges, compared with hand-breaking, are extracted from a table given by Mr. Hall.* * Trans. Soc. Engineers, 1879, p. 65. STONE-BEEAKING BY MACHINERY. 45 Locality. Sussex . . . . Great Ayton., West Coast . . Warwickshire . Somerset Material. Flints 1 Purbeck stone Boulders J Blue whin Trap, syenite, Welsh granite Rowley rag Carboniferous limestone. Gauge. in. 2 J and 1* 2 2i 2i 2J Cost of Breaking by Machine, per ton. s. d. 7 to 10 1 3 1 4 lOJ 6 Cost of Breaking by Hand, per ton. s. d. f Flints ..10 Purbeck 2 Granite . 2 Is. 6d to 2 1 10 2 3 1 At Mount Sorrel, Leicestershire, the stone, a hard trap, is passed through an improved Blake machine, and then through riddles separating the gravel from the 2^ inch Macadam, the residue which will not pass the 2 J inch mesh being passed through fluted rolls. Leaving out the cost of getting, &c., which is the same whether the stone is broken by machine or by hand, the costs of breaking in the two ways as obtained by taking quan- tities of 50,000 to 100,000 tons is as follows :— By Macliines, Cost per ton. By Hand, Cost per ton. Loading Breakinff s. d. 7 6 5 1 4 s. d. Labour and tools . . . . 2 2 Loading up 2 Locomotives 2 Repairs Locomotives 1 11 2 6 There is here apparently 7d. per ton in favour of machine breaking, but when the interest on capital and depreciation of machinery are added, there is really a very small gain by the use of machinery. The great drawback is the large amount of gravel and chips produced, which at Mount Sorrel amounts to more than one-fourth of the rough stone broken. 46 THE MAINTENANCE OF MACADAMISED ROADS. Stone broken by machines is not so durable as if hand- broken. There is always, even with the hardest stone, a certain amount of crushing, which is greater when the jaws become worn. A stone not so hard, such as mountain lime- stone, suffers so much from the crushing as to stand very little wear on a road afterwards. The stones are not so cubical in form dr so uniform in size as if well broken by hand. To Tise stone-breaking machines to advantage, they must be kept pretty constantly at work, and an annual turn-out of 12,000 to 18,000 cube yards of road metalling cannot under ordinary circumstances be used within a short distance of a fixed machine. There must therefore be a siding and railway communication to convey away the broken stone, and the cost of carriage by railway and carting soon adds to the price. A stone-breaking machine and its engine may be moved from place to place, but the former, when mounted on wheels, weighs 6 or 7 tons, and the engine which works it must be capable of drawing it from one place to another. Generally speaking, stone-breaking machines can be used to the greatest advantage when the material is difi&cult to break, and where there are facilities for distributing large quantities from one, or a small number of sources of supply. The loss of durability resulting from machine-breaking can be compensated for by the use of an increased quantity of mate- rials, and the economy of substituting machines for hand labour will generally be almost entirely a 'question of transport of the broken stone to the roads. Where stone is obtained here and there in small quantities, and is broken on the spot, or in the stone depots, a machine is not applicable. Cost of Road Material. Quarrying stone for road metalling usually costs, at ordinary rates of wages, 6i. to Is. per cube yard, according to the difficulty of the work, and stacking the stone for measurement, 2d. per cube yard. Breaking by hand costs from Is. M. or Is. 4d. to Is. lOd per cube yard for ordinary silicious rocks and the harder limestones, and 2s. to 2s. 6d for harder silicious and'igneous rocks. Igneous rocks are sometimes difi&cult and COST OF EOAD MATERIAL. 47 costly to quarry, and can then be broken at a comparatively cheap rate, owing to the small size of the fragments. Thus some hard basalts and traps cost no more than Is. 3d per cube yard to break, after having been raised from the quarry at Is. or more per cube yard. The cost of carting of course varies very much according to the distance. It can generally be done at about &d. per ton per nule, equal to about 6Jd per cube yard, by arranging for it at the time of year when work for horses is slack. On 290 miles of county roads in Carmarthenshire the cost of hauling stone from local sources was found to be a little less than one- half the total cost of the materials, or on an average Is. lOd. per cube yard, out of a total cost of 3s. 9^c?. On 130 miles in Eadnorshire the cost of haulage bore nearly the same propor- tion to the total cost. The conveyance of a good material by railway soon increases the cost to 6s. or 8s. per cube yard, and it is sometimes well to go to 12s. or 13s. per cube yard, or even to the London price of 16s. or 18s. per cube yard for first-rate material exposed to heavy traffic. The cost of wheeling out materials from depots or heaps about , 100 yards apart, and spreading them in sheets, is about 5d per cube yard, or a man can wheel out and spread 7 cube yards per day. When laid in small patches, the cost per cube yard is higher. In the county of Edinburgh, the average cost of a cube yard of materials for the turnpike roads in 1877 was made up as follows in the different districts : — Leeswade and Wrights- houses. Dalkeith and Post Boad. Cramond. Calder, Slate- ford, and' Coistciphine. Quarrying and quarry expenses Breaking Carting to depdts Oarting from dep6ts to road Cost before being spread Spreading Total cost on road 1 5i 2 Oi 2 7| Hi 7 1 7i 7 8i <. d. 1 4i 1 7 2 4 n s, d. 1 3i 1 lOJ 1 5 n 5 lOf 5f 4 Hi Sf 6 4* 5 5 t. d. 1 71 1 3 1 If 4§ 4 5 9| 5 2J 48 THE MAINTENANCE OF MACADAMISED KOADS. The materials were whinstone (trap), in the first, second and last-named districts, and syenite of a very hard nature, in the Cramond district, and they were principally machine-broken. The distance to which they were conveyed to dep6ts, in many cases by rail, and thence to the road, was often considerable. ( 49 ) CHAPTEE IV. COMPOSITION OF KOAD-COATING. Stone, when broken to a size fit for road material, is more bulky, weight ^for weight, than either the solid rock or the quarried stone from which it is derived. The late Mr. C. W. Merrifield, F.E.S., noted that, assuming that none of the faces are concave, and that there are no built up hollows, broken stone cannot lie looser than when all the pieces are of the same size and shape and are regular tetrahedrons, and when that is the case he showed that half the space is filled and half void.* Experi- ments confirm the conclusion thus arrived at. Herr Bolkel- berg states t that he found that broken stone, averaging in size from 3|- cubic inches in some experiments to from 4 to 6 cubic inches in others, consisted very nearly of half solid and half empty space, that rounded stones packed closer than angular ones, and left less void, and that by packing irregularly shaped broken stone in a chest the empty space could be reduced to as little as 40 per cent, of the whole. As a general result the size of the stones was without sensible in- fluence on the proportion of the empty space if the stones were of an even size, but stones of various sizes mixed together gave a smaller proportion of void, which diminished as the variety in the size of the stones was greater. The last observation as to the effect of various-sized stones on the proportion of solid to void explains the difference between the results of other observers. M. Berthault Ducreux states | that stone broken to pass a * A plane can be completely covered with tetrahedrons, of which the volume will be as one-third of the height. A complete set of tetrahedrons cannot be in- verted on the first so as to fit in, but half a set can be made to fit in with a whole set. This gives y + j = „ of space filled, and the other half empty. 3 6 2 t Zeitschrift des Architeoten- und Ingenieur-Vereins fiir das Konigreioh Hannover, 1856, p. 225. J Annales dea Fonts et Chauss^s. 1834, vol. vii. E 50 THE MAINTENANCE OF MACADAMISED ROADS. gau^e of If inch to 2 inches, and separated from the small stuff which breaking produces, contains 54 per cent, of solid stone and 46 per cent, of void. M. Gasparin gives * the propor- tion as 55 per cent, solid and 45 per cent. void. Mr. Leahy f gives as the result of experiment that 100 cube feet of stone, when broken to pass through a ring — IJ inch in diameter, measured 205 cube feet. 2 „ 1, „ 190 „ 2| n n „ 170 „ which gives the following proportions of solid stone to void : — Stone broken to IJ-inoh gauge : solid 49, void 51 per cent. )) »j -^ » J, It 53, „ 47 „ " »» ^ ti » 3, 5y, „ 41 „ In this case it would seem that the stone must have been more even-sized when broken to the smaller gauges. It appears from the weights per cubic metre, and the specific gravities of the 637 samples of broken materials used on the national roads of France, which were experimented on as already described, that the proportion of solid ranged from 49J to 57f per cent, of the whole, and was generally 52 or 53 per cent. Mr. J. Mitchelljt by beating down screened broken stone metalling of ordinary size in layers of 6 inches in thickness,' obtained a proportion of rather more than 59 per cent, of solid stone, thus agreeing closely with Bolkelberg's result with packed stone. ' The following are the weights of a cube foot of some of the stones generally used for road metalling : — Glee HiU stone 179i lbs. per cube foot. Other basaltic rocks 173 to 187 „ „ Syenite (Guernsey granite) . . 173| „ „ Limestone 154 to 172 „ „ Sandstone 156 „ 165 „ „ Takiag 55 per.cent. as the amount of solid stone contained in broken stone metalling, the weight of stone in pounds per * Annales des Fonts et Chauss^es, 1853. t Practical Treatise on Roads, p. 186. X New Mode of Constructing Streets, &c., p. 14. COMPOSITION OF EOAD-COATING. 51 cubic foot, multiplied by 27 X 0-55, or 14 "85, wiU. give the weight of a cube yard of the same stone when broken to road metalling. Thus, a cube yard of broken road metalling of compact mountain limestone weighing 172 lbs. per cube foot will weigh 172 x 14-85 = 2554 lbs. or 1 ton 2 cwt. 3 qr. 6 lbs. A simple proportion wUl show that in this case a ton of stone will produce rather less than ^^j cube yard of broken road metalling. Lighter stones will give a rather less proportion of broken road material per tofl, but in taking account of materials used, tons may be reckoned at ^ of a cubic yard. Gravel, though made up of a lighter material, contains a larger proportion of solid, and weighs heavier. A coarse flint gravel was found by the author to weigh 1 ton 5 cwt. per cube yard as it came from the pit. According to Mr. Leahy's experiments, stone, when broken to a IJ-inch gauge, measured nearly one-fourth more than when broken to a 2J-inch gauge. It thus appears that there is less of solid stone, as weU. as a proportion of small useless stuff, in a- cube yard of stone broken unnecessarily small. In road maintenance a coating of materials has to be dealt with which has been modified by wear into something very different from the broken stone originally spread, and a know- ledge of its constituent parts is necessary for its proper treatment. On pulling to pieces a specimen cut out of a good limestone road, kept in first-rate order, the author found that the stone in it which would not pass a |-inch ring, and which consisted of all sizes, from f inch up to the gauge of 2J inches, to which the stone had been broken, contained 55 per cent, of solid to 45 of void, being the proportions which broken stone has already been stated to contain. The stone of all sizes in the same specimen after everything that would pass through a cheese-cloth having twenty threads to an inch had been washed away, weighed, when not perfectly dry, 68 per cent, of an equal bulk of solid stone, thus giving a proportion of 68 solid to 32 void. In a consolidated road all. interstices are filled up either with small detritus or mud, and the author has found that specimens of consolidated limestone roads weigh from 161 E 2 52 THE MAINTENANCE OF MACADAMISED EOADS. to IGS^ lbs. per cube foot when the limestone of which they are made weighs 171^ to 172 lbs. per cube foot, the consolidated road thus being from 93^ to 95J per cent, of the weight of an equal bulk of solid stone. The same proportion was found to prevail in consolidated road surfaces composed of igneous rocks. These results agree with those recorded by M. Bardonnaut,* giving the specific gravity of a road 2 "40, when that of the limestone of which it was composed was 2 '57; and with a statement by M. Gasparin.f that the density of consolidated road to solid stone is as 240 to 255, which gives for the weight of consolidated road from 93 J to 94 per cent, of the weight of an equal bulk of solid stone. AssumiQg, as experiments show, that broken road materials contain 55 per cent, of solid stone, a cube foot composed of broken stone which weighs in the solid 172 lbs. per cube foot will weigh 172 x 0*55, or 94^ lbs. By the process of con- solidation in the road it is crushed and compressed together till it weighs, as in the roads above referred to, say 162 lbs. per cube foot, and the bulk it then occupies must be in the inverse 94i ^ proportion, i. e. j^ = • 583, or 58 per cent, of its bulk before it was spread on the road. Or put in another form, it takes nearly 1| of road metalling measured by bulk or thickness before it is spread to make 1 of consolidated road surface. These proportions may be expected to- vary with the amount of solid stone in the materials, and of, detritus contained ia the road. M. Berthault Ducreux J states that as a mean result he found that 1 cubic metre of limestone, broken to l|-inch to 2-inch gauge, gave • 71 cubic metre of consolidated road, or that 1'41 of broken stone was required to make 1 of consoli- dated road. M. Bardonnaut § gives as the result of experiment that 1 cube metre of a consolidated limestone road contained 1 • 64 cube metre of materials when pulled to pieces and sorted in various sizes. M. Graeff|| found that with schist the pro- portion was from 1*30 to 1-55 and the mean very nearly lv41 of materials to 1 of consolidated road. * Annales desPonta et Chausades, vol, xvi. 1838. t Ibid., vol. vi. 1853. J Ibid., vol. vii. 1834. § Ibid., vol. xvi. 1838. 1| Ibid., vol. ix. 1865. COMPOSITION OF EOAD-COATING. 53 It may be assumed therefore that it takes from 1-3 to 1 • 7 by bulk or thickness of road materials, as measured before they are spread, to make 1 of consolidated road, or that materials, when consolidated in a road, occupy from • 77 to • 58 of the space they did before they were spread. A proportion of 1^ of materials to 1 of road, or | of road-coating to 1 of materials, will generally not be far from the truth. So long ago as 1834* experiments were made by M. Berthault Ducreux to ascertain the composition of consolidated road surfaces by separating the different sizes of the materials. Taking 2 centimetres (= 0'8 inch), which was the size of the mesh used to separate the small gravel from the road materials, as the gauge for stone, he found that the proportion of stone above 2 centimetres in the coatings of different roads was generally from 18 to 31 per cent, of the whole, rarely over 35 or less than 9 or 10. The proportions of the smaller sizes appear also to have been ascertained, but are not recorded. The gauge of 2 centimetres or 0'8 inch has since been generally adopted by French engineers as that above which the material in a road is ranked as stone, and below which it is called detritus. Though the general result of wear must be gradually to reduce the materials . from the size at which they were put on the road to the mud and small detritus scraped off, it is difficult to draw any line between stone and detritus, or to say at what size a stone ceases to be useful. The pro- portion of large stone would often be a fallacious measure of a road's strength. The author has found portions of road which always go to pieces in wet weather to have an unusually high proportion of large stone, the reason being that large quantities of materials are continually laid down on a soft, wet subsoil, and the road is weak and bad for want of drainage, though full of stone. On the other hand, in a dry situation, the pro- portion of large stone may be but small, and the road perfectly good under traffic which would convert a more stony but Hi-drained one into a bog. Nevertheless, under the same conditions, a road with an undue proportion of small detritus and mud is less able to resist the wear of heavy traffic, and * Annales des Fonts et Chaussees, vol, vii. 1831. 54 THE MAINTENANCE OF MACADAMISED EOADS. Analyses of the Composition of Eoad-ooatinqs. Locality. Fkbgentages. No. Stohe. Mud, &c., Over 1 in. Over 1 in., under | in. Over 1 in., under i in. Over^ in., under | in. under j^ in. 1 Pembrokeshire mail road, west of Canaston Bridge — ^Mountain limestone 8 inches thick, as , good as a road can be ; upper 40-6 53-5 12-9 13-2 7-1 20-2 33-3 191 2 Do. do. do. ; lower 3J inches 3 KidweUy road, near 6 m. — Moun- tain limestone 3J inches thick, on strong clay subsoil 45-0 12-7 6-3 14-5 21-5 4 Kidwelly road, near the same place — ^Mountain limestone 1§ inch to 2 inches thick ; road not metalled for three years at least 29-5 17-4 9-9 22-6 20-4 5 Brecon and Criokhowell roa^, east of Bwloh — Bwlch limestone 7 inches thick, then subsoil, very good road ; chosen as the cleanest and driest part of the road 33-5 14-9 8-1 18-5 24-8 ^ 6 Brecon and OriokhoweU road, near Scethrog — Bwloh limestone 5J inches thick, on field stone 6 or 7 inches ; chosen as the softest and muddiest part 21-5 16-0 10-5 28-0 24-0 7 Brecon and Hay road — Mountain limestone 2 to 3J inches thick, on a pitched foundation . . 23'5 14-9 9-0 32-4 20-2 8 Near Presteign toU-gate — Nash Silurian limestone 4| inches thick 36-9 11-9 7-5 17-9 25-8 9 Pembrokeshire mail road on em- bankment near Cock's Hill — Camphill stone IJ inch to 2J inches, on grey stone, 8 inches thick altogether ; upper 2 inches 32-4 16-9 8-8 20-9 20-9 10 Llandore road — Copper slag, siUoious and limestone ; lower 3| inches of road 6^ inches thick 52-1 10'5 4-2 9-9 23'4 COMPOSITION OF EOAD-COATING. Analyses of the Composition op Eoad-coatinqs — Continued. 55 LOOAIITT. Pebointases. No. Stohb. Mud, &c.. Over 1 in. Over 1 in., under J in. Over 1 in., under f in. Over A in., under | in. 11 Llandore road — ^Nearly aU copper slag ; upper 3| inohea of the same specimen as 10 44-3 10-4 6-1 19-1 20-0 12 Llansamlet road — Copper slag on furnace cinders 40-1 9-1 6-1 30-2 14-4 13 Newtown road, Radnorshire — driver stone 5J inches thick, on strong clay, drainage bad, much out up in wet weather 36-2 17-5 45-0 14 Ditto ditto near same place. . 40-5 10-5 .. .. 49-0 .. 15 Penybont Common — Graig stone (igneous) SJ inches thick, on drv clav 47-0 11-7 .. 20-7 20-5 16 Near New Radnor — Gore stone (basalt) 3J inches thick, on a dry bottom ; stood timber haul- ing well in bad season 46-8 14-3 6-3 10-7 21-9 17 Near Penybont station — Llanfawr stone (igneous) SJ inches thick . 44-0 11-8 7-5 14-8 21-9 18 Maa road, 2 J m. S. of Llandegly — Eddw stone (igneous) 3§ inches thick, on dry subsoil 45-9 11-7 6-1 17-4 18-9 19 Between Llandegly and Penybont — Graig stone (igneous) 6 inches thick, on dry BubaoU 43-9 11-8 8-0 16'8 19-5 the action of wet or frost, than one with a large proportion of stone. Generally the materials are smaller in size, and there is a larger proportion of detritus, near the surface than in the lower part of the crust of a good road. When road metalling is put on in great thickness at once, the proportion of large stones remaining in the consolidated surface is greater than when thin coats are applied, and 56 THE MAINTENANCE OF MACADAMISED EOADS. 80 or even 90 per cent, of the whole may be found to be over f inch or f inch in diameter in a road newly made of materials broken to the usual gauge, and consolidated with a roller. The above table shows the results of some of the ex- periments made by the author, and under his directions, on the constituent parts of different roads. Blocks of the whole thickness of the macadamised coating were cut out and pulled to pieces. The stone was sorted by sieves to the various sizes, and the mud, &c., was separated by washing through a cheese- , cloth having twenty threads to an inch, which allowed every- thing under ^ inch to pass away. Newly stoned portions were avoided in taking the specimens, and the points chosen were such as to give a fair sample of the composition of the road. The materials employed had been in all cases broken to the gauge of 2^ inches or 2^ inches, and the roads were maintained on the same general system with ^thin coats of stone. It will be observed that of stone above | inch, a gauge rather larger than the 2 centimetres of the French engineers, the proportion varies from 21 J to 53 J per cent., and only exceeds 50 per cent, in the lower portions of two roads. Of stone above f inch, the proportion varies from 37 J to 66|. The weakest in stone of the larger size, either above f inch or 1^ inch, is No. 6, a specimen from a point chosen as being by reason of its situation the softest and muddiest on a very good limestone road from which No. 5 was taken at a clean and dry spot for comparison. A specimen almost as poor in large stone is No. 7, from a road having a pitched foundation, over which the broken stone had worn thin. The roads com- posed of igneous rocks, traps, and basalts, appear always to abound in large stone. The stones probably do not split up when once in the road, either from the action of the traf&c or the weather ; but are reduced more gradually by attrition. The constituent part which exhibits the most constant pro- portion is the mud and other small stuff washed out, which in aU specimens but one is from 19 to 25| per cent, of the whole. Two specimens in which extreme proportions of mud COMPOSITION OF EOAD-OOATING. 57 appear, viz. No. 1 and N"o. 5, are from roads both excellent, and between which it is hard to say which was the better. No. 12, in which only 14^ per cent, of mud, &c., was found, is from a road made of copper slag, on a foundation of furnace cinders, and covered with a binding of red ashes. This piece of road was constructed under the author's directions, two years and a quarter before the sample was taken ; and as No. 11, which is also of copper slag, but an old road, contains 20 per cent, of mud or small stuff, it may be presumed that the new road will ultimately reach a proportion not different from the rest. It appears from the author's examinations that, whether the road be a strong good road 7 or 8 inches thick, a thin worn coating over a pitched foundation, a road reduced to 1^ inch to 2 inches of limestone on a clay subsoil, a road from its situation requiring a great deal of scraping, or one requiring very little, and whatever may be the material, or the traffic, the proportion of mud, &c., which can be washed out, and which forms the binding material, is about the same. For this to be the case, it is no doubt necessary that the mud should be constantly removed as soon as it is formed and appears on the surface, otherwise the proportion would be far higher in many roads. As an instance of this, the analysis by Mr. Joseph Mitchell of the crust of the road in the Mall, St. James's Park,* may be cited, which shows as much as 40f per cent, of mud, 9 per cent, of sand and stones up to -^ inch in size, 24j per cent, of stones between ^ inch and J inch, and only 26 per cent, of stones over ^ inch diameter. An examination of the scrapings removed from the lime- stone roads from which samples 5, 6, and 7 were taken, proved that about two-thirds consisted of mud, &c., which would wash out through a cheese-cloth having twenty threads to an inch, the remaining third being grit of about the size of small shot, and up to ^ inch in diameter, and it appeared that of the whole body of the road about one-third consisted of mud and grit of the same composition as the scrapings. "When in the condition of a stiff mud, such scrapings consist of about 70 per cent, by bulk of dry detritus, and 30 per cent, of * New Mode of Constructing the Surface of Streets, p. 15. 58 THE MAINTENANCE OF MACADAMISED EOADS. water, and these proportions are the same when the road material is sUicious. Water to the extent of 3>0 per cent, adds nothing to the volume of the dry detritus, but a greater propor- tion increases the bulk and renders the mud more or less liquid. The large proportion thus found to exist in the coatings of the best roads, of small stuff which only requires water to make it mud, shows the strong necessity for keeping roads dry, and this necessity must be the greater as the proportion of detritus is allowed to increase in the road beyond the amount absolutely necessary to fill the voids between stones closely wedged together. In the latter case an excess of moisture will destroy all coherence in the binding material, by which alone motion among the stones in the road- coating is prevented. ( 59 ) CHAPTEE V. DRAUGHT. WHEELS, AND WEIGHTS ON THEM. Draught. The resistance of wheeled vehicles to traction is made up of two parts, the friction of the wheel on its axle and the rolling and rubbing resistance between the wheel tire and the surface of the road. The former has nothing to do with the road, and may be passed by with the remark that it is nearly the same at all velocities, and is, in wheels of ordinary construction and proportions, equal to yj^ to y^ of the weight on the axle, or 17 to 22 lbs. to a ton of load. The resistance between the tire of a cylindrical wheel and the road depends on the rough- ness of the surface and its compressibiKty. If the roughness of the surface be considered as small obstacles in the path of the wheel, the force necessary to overcome them can be shown to be nearly in the inverse proportion to the square root of the diameter of the wheel. Edgeworth,* and others after him, considered that the resistance from compressibility of th6 surface under the wheel was of the same character, and that the whole resistance between the tire and the road was in the inverse proportion to the square root of the diameter of the wheel. This view was strongly maintained by Dupuit, in opposition to Morin, whose experiments led him to the conclusion that the resistance to rolling varies inversely as the diameter. The difference be- tween .these two ratios is very great. If the draught increases inversely as the diameter, it would be reduced to one-half by doubling the diameter of the wheel, while, if it tacreases only in inverse proportion to the square root of the diameter, the same * Roads and Carriages, 1817, p. 48. 60 THE MAINTENANCE OF MACADAMISED EOADS. result would only be attained by making the diameter of the wheel four times as great. From experiments made at the Eoyal Agricultural Show at Bedford in 1874, with Easton and Anderson's horse dynamo- meter, it appeared that 1 lb. of draught was expended on moving every 35 '1 lbs. of weight resting on the fore- wheels of a waggon, 3 feet 5 inches diameter, as compared with 58- 7 lbs. on the hind- wheels, of 5 feet diameter.* This gives an increase of draught in rather a greater ratio than inversely as the diameter, and is consequently even more favourable to large wheels than Morin's proportion. Other experimenters have arrived at results giving inter- mediate ratios, and it is natural to suppose that on different roads there may be influences by which the total resistance may be modified in either direction. At any rate, there is no doubt that large wheels are favourable to draught, and cause less wear of the road. Both Dupuit and Morin considered that the width of the wheel tire had only an unimportant influence on the draught of vehicles. Dupuit concluded that on even surfaces, whether soft or hard, the resistance to draught was independent of the width of tire. Morin's experiments showed that on solid macadamised roads in a good state of repair, the resistance to rolling was almost independent of the width of tire, while on compressible surfaces, such as earth, sand, or gravel, it decreased as the tire was wider, in a proportion depending on the natm-e of the ground. On rough uneven surfaces, such as a stony road, Dupuit considered that draught was lessened by wider tires, and Morin that tires 3 or 4 inches wide had an advantage, but that beyond that width the resistance to draught was nearly inde- pendent of the width of the tire. Experiments by other observers show that on a gravel road in good order, there is no sensible difference in the traction, whether the tires are narrow, or nearly 4 inches wide, but that the latter have an advantage on an earth road, or on clay soil. The resistance due to gravity on inclined roads must of course be allowed for in all considerations of draught. It is very * Journal of Royal Agricultural Society, 1874, p. 683. DRAUGHT. 61 nearly equal to the gross load divided by the rate of gradient, thus, on a gradient of 1 in 20 the increase of draught due to gravity "^iU be ^ of the gross weight of the vehicle and its load. All observers agree that the draught is less as the road is smoother, harder, more solid, and less compressible or flexible under the load. There is not sufi&cient elasticity in the coating of a road to give back to a wheel from behind the force expended in compressing or pushing down the surface before it. On a yielding road the wheel is thus always in a hollow which it never gets out of, and the horses are always drawing up hiU. With respect to excessive draught arising from irregularity of the surface, Morin says* that experiments with the same waggon running over various parts of the same road, maintained with the same materials, in the driest season of the year, showed that, while upon portions in good condition the tractive force exerted was from ^ to ^ of the load, on parts badly main- tained, having ruts and hollows, it rose to ^ and ^ ; that is to say, that three horses would be required on the badly main- tained road to do the work of two on the well-maintained road. The results of two series of experiments made by Morin on macadamised roads in good condition, maintained with sHicious pebbles and limestone, gave a mean draught of -^.j and ^.^ of the gross load. On some parts in a perfect state the draught was as little as ^. The waggon employed had fore-wheels 2 feet 11 inches and hind- wheels 4 feet 7^ inches in diameter, with tires 4 inches wide, and was loaded with about 5^ tons. The trials were made in the end of summer, when the roads were in their best condition, and the draught is the actual tractive force employed, including of course the axle friction. The proportion of draught to load with large wheels is stated by other observers to be from ^ to ^ on a dry and level mac- adamised road in first-rate condition, increasing to ^- or ^ when the road is covered with mud and loose stones, and to ^ or even more on freshly laid unconsolidated stones. The trials at the Eoyal Agricultural Show at Bedford in 1874 gave the average draught of single horse carts having wheels * M&anique Pratique, p. 349. 62 THE MAINTENANCE OF MACADAMISED EOADS. 4 feet 6 inches to 5 feet 2 inches in diameter, and tires SJ inches and 4 inches wide, loaded to about 30 cwt., as about -^ of the gross load on a level macadamised road at a walking pace. With other carts, having wheels 4 feet 9 inches to 5 feet 1 inch in diameter, and tires 4 inches and 4^ inches wide, and a gross load of 41 to 45 cwt., the draught was on the average ^ of the gross load under the same circumstances. With waggons having fore- wheels 3 feet 4 inches to 3 feet 5 inches in diameter, and hiad-wheels 4 feet 9 inches to 5 feet 1^ inch in diameter, tires 2J inches to 4J inches • wide, and a total weight of 61| to 103 cwt., the average draught was ^ of the gross load. The draught is less with carts than with waggons, because in carts the whole load rests on large wheels, whereas in waggons, one-third or more of the load rests upon the fore-wheels of smaller diameter. These trials may be assumed to have been made with vehicles in the best possible condition to give favourable results. The tractive force required on every part of the road between London and Shrewsbury was measured by Sir J. MacneiU with an instrument devised by him for the purpose. The results are recorded in elaborate tables,* which give the force exerted to draw a common four-wheeled waggon, empty, weighing about 21 cwt., during dry weather in March, at about 2J miles per hour. A correction is applied to the draught actually shown by the instrument, to give the tractive force on a horizontal road. The general results of the experiments, as given by Telfdrd.t are as follows : — Draught on a well-made pavement 33 lbs. = yL ,, ,, broken stone surface on old flint road .. 65 „ = -jV ,, ,, gravel road 147 „ = Jj ,, ,, broken stone road upon a rough pavement foundation .. ' 46 „ = -^^ „ ,, broken stone surface on a bottoming of concrete 46 „ = ^^ These results have been often quoted, but it does not appear in what way they were deduced from the recorded observations. They can only be looked upon as averages from which many of * Appendix to 7th Report of the Holyhead Road Commissioners, 1830. t 7th Report, &c., p. 13. DRAUGHT. 63 the observations differ widely, and without apparent cause. Accorduig to these figures, the draught on a broken stone road over a paved foundation or over a bottoming of concrete was -g^, and on a broken stone surface on an old flint road -^ of the load drawn, while on a gravel road it rose to ■^. With respect to the traction on roads of different materials. Sir J. Macneill states* that he found from his experiments that granite gave the best road surface in wet' and limestone in dry weather, while gravel was always very imperfect. The effect of springs in reducing draught is that they enable the wheels to rise and fall over inequalities of the road, while the load on them moves forward without being sensibly raised. The more perfect the elasticity of the springs is in a vertical direction, the greater is the reduction of draught, but any elas- ticity in the direction of the traction tends to increase the draught. The good eflfect of springs is much greater at high than at low velocities. Morin considered that at a walking pace the resist- ance was the same for vehicles with or without springs on roads of all sorts. The trials at Bedford before alluded to gave 10 lbs. per ton less draught with a spring waggon, compared with one without springs, on a hard road, and the difference was also noticeable, though in a much less degree, on arable land. The general conclusions arrived at by Morin from his expe- riments on draught are as foUows.f The resistance to rolling of vehicles on solid metalled roads and pavements is proportional to the weight and inversely pro- portional to the diameter of the wheels. On solid roads the resistance is very nearly independent of the width of the tires when it exceeds 3 to 4 inches, but on compressible surfaces it decreases in proportion to the width of the tire. The resistance increases vsdth velocity on hard roads, but is independent of velocity on soft surfaces. Springs diminish resistance at high speeds, but not at slow speeds. * Evidence, Committee on Tumpiks Roads, 7833, p. 128. t Experiences sur le Tirage des Voitures, p. 187. 64 THE MAINTENANCE OF MACADAMISED KOADS. Wheels, and Weights on them. The regulation of the form and construction of wheels has been the subject of legislation ever since the beginning of the century. In this country one of the early results was to bring into use an excessively broad conical wheel with a tire con- siderably rounded or barrelled, and often with a middle tire projecting so far beyond the others that it constituted the wheel on a hard road, and which was on the whole about the worst form of wheel that could have been devised. The roundiug of the tire and the projecting bands were of course adopted to give the semblance of a broad wheel without the reality, but to some extent they were attended with advantage. A conical wheel can only be made to travel in a straight course by a constant twisting action at the surface of the road, and the wider the bearing surface of the tire, the greater the grinding and dislo- cating of the materials must be, and wheels 12 and 16 inches wide bearing fairly over their entire width would have been worse for the roads, as well as for the horses. A cylindrical wheel, having a tire bearing flatly on the ground, and of the same diameter on each side of the wheel, which would roll fairly on the road, was strongly advocated, and on some turnpike trusts was encouraged by lower tolls. The conical or dished wheel has, however, practical advantages which have kept it in general use, and cylindrical vheels are stQl the exception. The inclined spokes of the dished wheel give it strength to resist lateral shocks, and afford greater room for the body of the vehicle, and the objections to the conical form diminish with the breadth of the wheel. When the tire is flat, or only slightly rounded, and with the nails entirely countersunk, there is little to be said against the dished wheels of the moderate breadth at present in use. The General Turnpike Act (1823) (3 Geo. IV. cap. 126), regulated the weights to be allowed to waggons, carts, &c., having wheels of the breadth of 9 inches, 6 inches, 4^ inches, and under 4J inches, in wiuter and in summer, according to the following table : — WHEELS, AND WEIGHTS ON THEM. 65 Description of Vehicles. Weight of Carriage, and Loading. Pressure per Inch of Width of Tire. Summer. Winter. Summer. Winter. Waggon with 9-inoh wheels Cart „ „ Waggon with 6-inch wheels Cart „ Waggon with 4 J-inch wheels Cart „ „ Waggon with wheels less than 4§ inches . Cart „ „ Tons cwt. 6 10 3 10 4 15 3 4 5 2 12 3 15 1 15 Tons cwt. 6 3 4 5 2 15 3 15 2 7 3 5 1 10 Cwt. 3-6 3-9 4-0 5'0 4-7 5-8 |.i/7-5 s'\7-0 Cwt. 3-3 3-3 3-5 4-6 4-1 5-2 6-5 6-0 Additional toll was chargeable for overweight above these weights, and the use of broad tires was encouraged by rendering vehicles with wheels of less breadth than 4^ inches chargeable with one-half more toll than those with 6-inch wheels, and those with wheels of 4J inches breadth and less than 6 inches with one-fourth more toll than those having 6-inch wheels. A vehicle having upright cylindrical wheels, with the nails countersunk, was charged two-thirds the toll otherwise payable. These regulations did not extend to coaches and carriages, and applied only where the Turnpike Acts were in force. They were repealed in South "Wales in 1844, and the width of wheels was subject to no restrictions. It will be observed from the above table of weights that all wheels of less width than 4^ inches were treated alike, so that a cart or waggon having wheels 2^ inches wide could carry as heavy a load as one with wheels 4^ inches wide, and that the pressure per inch of width is far greater on these narrow tires than with wheels 4^ inches wide and upwards. Increased tolls on narrow wheels did not prevent their use, nor the carrying of heavy loads on them, and as tolls were abolished they became more general, and it seemed unlikely that fresh regulations would take the place of those expiring with the Turnpike Acts, The Highways and Locomotives Act of 1878, however, gave power to the County Authorities to make bye-laws regulating 66 THE MAINTENANCE OF MACADAMISED - EOADS. the width of wheels in proportion to the weight carried, and the power has been generally exercised. Usually the weights allowed by the General Turnpike Act have been followed with some modification, and sometimes with additions to provide for heavier loads, or to restrict the weights to be carried on wheels of a less width than 4^ inches. It is doubtful, as will be shown further on, whether there is any advantage in limiting the loads to be carried on wheels of 4^ inches and upwards, and while it is certain that narrow wheels with heavy loads cause the greatest damage to roads, it is difficult to enforce bye-laws against them and to put new restrictions on existing vehicles. The following average weights of coaches and waggons, with the load on each wheel, and the pressure per inch of width of tire, were given by Sir J. Macneill in 1831 : — * Description of Vehicles. Weight on the Average. Breadth of Wheel. Pressure of each Wheel. Pressure on each Inch of Breadth. Mail-coach Stage-coach Van Waggon )) » Tons. 2 ^ 6 Inches. 2 2i 9 6 4 Cwt. 10 12-5 21-25 30-0 22-5 17-5 Cwt. 4-40 6-25 8-29 3-33 3-75 4-37 To which may be added the particulars given on the following page, of some of the heaviest loads that now usually come upon roads. It will be observed that the pressure per inch of tire is much greater in the case of heavy vans and waggons with narrow wheels than in the case of traction engines and trucks with wide tires, and it must be remembered that the effect of wear is to round the edges of tires, so that the pressure on the narrow tires is generally greater than the tables show. The pressure per inch/ of width of tire cannot, however, always be taken as a fair measure of the load on a road ; a good deal * Evidence, Committee on Steam Carriages, p. 95. WHEELS, AND WEIGHTS ON THEM. 67 will depend upon the sort of road. A strong hard road, on a good foundation, may bear a considerable load on narrow tires without perceptible damage being produced, while a more yield- ing road will break down under a traction engine, although the pressure per inch of tire is far less. DeBcription of Vehicles. Ereadth of Tire. Load on Wheel. Load per Inch of Width of Tire. Cart : weight 10 cwt., load 32 cwt Cart : weight 10 cwt., load 35 cwt Pickford's waggon : weight 1 ton 1 cwt., load 2 tons Pickford's waggon : weight 1 ton 7i cwt.. load 3 tons Railway Tan : weight 1| ton, load 3 J tons.. Waggon : weight 1 J tons, load 5 tons Waggon : Weight empty 21 cwt. j „ when loaded, on fore wheels, 46 „ > „ „ „ hind „ 56 „ ) Total .. 102 „ 11 -ton traction engine, weighing 12 tons with coal, water, &c., two-thirds weight on driving wheels 8-ton traction engine, weighing 9 tons with coal, water, &c., two-thirds weight on driving wheels Waggon for steam traction : weight 1 ton 10 cwt., load 6 tons Waggon for steam traction : weight 1 ton 8 cwt., load i tons Waggon for steam traction : weight 1 ton 5 Cwt., load 3 tons 15 -ton steam road roller IncheB. 4 2J 2J 3 3| 18 16 8 6 4 20-24 Cwt. 21-0 22-5 15-25 21-87 25-0 32-5 28-0 80-0 60-0 37-5 27-0 21-25 75-0 Cwt. 5-25 9-0 8-75 8-33 8-66 7-0 4-44 3-75 4*69 4-5 5-31 3-12-3-75 The crushing action of heavy loads on narrow tires is of course severe at the surface of the road, and such as only the strongest materials can withstand. Sir James McAdam, speak- ing from experience of the Metropolis roads, considered that 2 tons was the maximum load that should be allowed on any one wheel 4J inches broad, which gives a pressure of nearly F 2 68 THE MAINTENANCE OF MACADAMISED EOADS. 9 cwt. per inch of width. For the generaKty of roads this is undoubtedly too much. Telford was of opinion that the weight should not exceed a ton upon each wheel * and Sir J. Macneill, taking the road from London to Shrewsbury as a criterion to judge by, considered that a wheel ought to be an inch in width for every ton that a carriage and its load would weigh, thus giving 1 inch of tire for every 5 cwt. of load on the wheeLt The diameter of the wheel, as influencing the pressure on the road, may be left out of account for wheels of common size, on ordinary road surfaces. It is, however, necessary to consider the causes of wear of materials in roads before proceeding further with this subject. * Evidence, Committee on Highways, 1819. t Evidence, Committee on Steam Carriages, 1831, p. 95. ( 69 ) CHAPTEE VI. WEAK. The wear of material in roads is due to two causes, the traffic and the weather, which react on each other, so that it is not easy to distinguish their effects. Sir J. Macneill, who as resident engineer under Telford, on the London and Holyhead and Liverpool roads, had considerable experience of road maintenance, estimated* that, of the total wear, 80 per cent, on the average was due to the traffic, and 20 per cent, to atmo- spheric causes, and of the 80 per cent, due to the traffic, 60 per cent, was due to the wear of the feet of the horses drawing and 20 per cent, to the wheels in the case of fast coaches, and 44^ per cent, to the horses' feet, and 35J per cent, to the wheels in the case of waggons. Telford and Sir J. McAdamf both agreed with Sir J. Macneill that the injury done to a road by the feet of the horses drawing was greater than that from the wheels, since the former tore up the surface, and displaced the materials, while the crushing and grinding action of the latter was com- paratively small on a hard smooth road. With fast coach traffic on a strong road no doubt this was true, but it is otherwise when heavy loads travel on a comparatively weak road. The wear from horses' feet will of course be increased by anything which increases the draught, such as unevenness of surface, or a yielding road. Sir J. Macneill considered that the wear due to atmospheric causes might be less than 10 per cent, of the total wear on a properly made road, in an open situation, and might be more than 30 per cent, on a weak road, on a clay subsoil, and shaded by trees. The grounds on which the estiniates of the wear from * Evidence, Select Committee on Steam Carriages, 1831. f Ibid. 70 THE MAINTENANCE OF MACADAMISED EOADS. atmospheric causes were based are not stated. The relative wear to the road from horses* feet, and from wheels, was deduced from the wear of iron in the horses' shoes and in the wheel tires. The total wear as well as the relative proportions caused by the traf&c and by the weather are influenced by the nature of the- materials, the subsoil, drainage, situation, strength of the road, the care with which it is maintained, the traffic, and other circumstances which may vary almost from yard to yard. Any general estimate, therefore, by however good an authority, must not be considered as even approximately true for any particular case, and there are sometimes wider differences in the proportion of wear due to traffic and weather than the above. The passage of vehicles over a road produces several effects, which it is important to distinguish. There is, first, the grind- ing and crushing action of the wheels and horses' feet on the surface, and there is, secondly, the effect of the load in giving rise to bending and cross-breaking strains throughout the whole thickness of the road-coating. Wlien the materials are loose and unconsolidated, either because they are freshly laid, or from having been disintegrated, there is a third action, namely, a displacement of them by the wheels and horses' feet, accompanied by a rubbing together of the stones among them- selves. This is the cause of great wear and waste of materials laid in thick coats. On a thick strong consolidated road, or on one of less thick- ness on a hard foundation, the bendiag and cross-breaking tendency of the load produces no sensible effect ; there is no movement in the body of the road, and the wear is confined to the grinding and crushing of the materials at the surface. This is the most favourable condition under which road materials can be subjected to wear, and it rarely occurs without the addition to some extent of the third-named effect, namely, a movement and rubbing among the materials, extending to the small depth to which the wheels affect the surface. In propor- tion, however, as it is confined to the surface and approximates in character to that on a paved roadway will the wear be small and gradual. A good limestone road, strong enough for the traffic it has WEAR. 71 to carry, sometimes affords an instance of wear confined to the surface, even on a yielding subsoil. The cementing nature of the limestone detritus gives the crust enough transverse strength to resist bending and cross-breaking under the loads to which it is exposed, and it may be compared to thick ice bearing heavy weights on water. It is possible that the case of the limestone road over the morass referred to by McAdam,* on which the wear was small, may be thus explained, and that, although the subsoil was a bog, the coating was so strong that there was no cross-breaking or bending, nor any wear except at the surface of the road. Cases have come under the author's observation where the cohesive strength of a limestone coating has enabled it to carry the ordinary traffic on a wet undrained subsoil with- out excessive wear, untU bending and cross-breaking was set up by heavier loads or some unfavourable circumstance. When this happened, the break-up was serious, and was due to the badness of the subsoil as much as to the thinness of the coating. The latter would have been thick enough on a dry subsoil, and a thicker coating would have saved the road from damage on a soft subsoil. On a weak road, such as one of insufficient thickness or cohesion on a yielding foundation, bending and cross-breaking produce the effects which were accurately described by Sir J. MacneiU : " If the road be weak or elastic and bend or yield under the pressure of the wheels, the particles of which it is composed will move and rub against each other, or perhaps break by the action of the heavy wheels over them."t It is by a process of this sort that a very large proportion of the wear of roads is occasioned. In consequence of want of drainage, or of insufficient strength on a bad bottom, continual bending and cross-breaking goes on under passing loads. The wear of materials thus caused takes place throughout the whole thickness of the road-coating, and is of course all in addition to the surface wear. It is aggravated by the softening action of the water which finds its way through the cracks which must attend bending in the road-coating, and the displacement of materials at the surface by the wheels and horses' feet is much greater than on a strong * Ante, p. 8. t Evidence, Select Committee on Steam Carriages, 1831, p. 97. 72 THE MAINTENANCE OF MACADAMISED EOADS. road. Stones are forced down into the sutsoil, and the latter rises up and becomes mixed with the metalling, so that .it is sometimes difficult to make out where the road-coating ends and the subsoil begins. Such a road can only be kept in tolerable order by an exces- sive outlay for maintenance, which would be avoided, and money in the end be saved, if the wear were lessened by proper drain- age of the subsoil, and by giving the road-coating sufficient thickness to carry the traffic. MacneiU says that " where an accurate experiment was made, the'wear was found to be 4 inches of hard stone where it was placed on a wet clay bottom, while it was not more than half an inch on a solid dry foundation, or with a pavement bottom on a part of the same road where it was subject to the same traffic,"* and instances might be given where the quantity of materials required to keep a piece of road in order has been reduced to one-third or even less by drainage alone. On roads of all sorts a reserve of strength, in the shape of a greater thickness of materials than is absolutely necessary, is always very desirable. The wear is less under the same traffic on a stronger road, which is better able to stand heavier traffic should it come upon it, or to bear a reduction in the quantity of materials to be laid should it be necessary to make it. Surface Wear. When a wheel meets with an obstacle in passing along a road, the force necessary to overcome the resistance to the for- ward motion of the wheel may be resolved into a pressure acting vertically tending to compress the obstacle into the road, and a force parallel to the surface tending to push forward the obstacle in the path of the wheel. The latter force is the greater in proportion as the diameter of the wheel is smaller ; it tends to disintegrate the road-coating, and is far more destructive than the vertical pressure, or than the greater impression which smaller wheels make. Morin points out f that a simple experi- * Evidence, Committee on Steam Carriages, 1831, p. 97. I M&anique Pratique, p. 356. SURFACE WEAR. 73 ment will confirm this. If one takes stones about 3 inches in diameter, and puts them on a somewhat wet and soft road before the wheels of a vehicle, they will be- pushed forward by the small fore-wheels, and plough up the surface of the road, while the large wheels wiU press them down, and generally pass over without displacing them. The greater disintegrating effect of small wheels holds good equally when the obstacle is a compressible surface. Morin's investigations on draught having established a con- nection between the tractive force exercised and the destructive effects produced, a series of experiments having more especial reference to the wear caused by vehicles to macadamised roads was undertaken by him.* Vehicles in other respects the same, but with diameters of wheels, breadth of tires, or load, different in different experiments, were made to pass and repass over the same tracks, which were sometimes kept watered to accelerate the wear. The state of the tracks or ruts produced by the wheels was carefully examined and compared from time to time. The roads experimented on were nearly level, about 13 inches thick, of a silicious gravel, in good condition, without hollows or ruts or newly laid materials. The loaded vehicles represented traffic of a heavy nature, but the roads were so strong that the wear' may be assumed to have been limited to the surface. The effect of the diameter of the wheels on their destructive effects on roads was shown by experiments with three vehicles loaded with equal weights of 4 tons 17 cwt. each, having wheels 4 • 6 inches wide in the tire, but with diameters 2 feet 10^ inches, 4 feet 9 inches, and 6 feet 8 inches respectively. After 980 tons had been transported, the tracks of the smallest wheels had deep ruts of unequal depth, the next size well-marked ruts almost as deep, while there was only a slight trace of the passage of the large wheels of 6 feet 8 inches diameter. The road was 1 foot 2 inches thick, and was watered freely." The effects of the width of the wheel tires on the road were shown in the same series of experiments. Three similar vehicles with four wheels of the same diameter, having cylin- drical tires of 2 • 4 inches, 4 • 6 inches, and 7 inches respectively, * ExperienceB sur le Tirage des Voitui-es. 74 THE MAINTENANCE OF MACADAMISED EOADS. were eq[ual]y loaded to 5 tons 8§ cwt. After the vehicles had made a number of passages equivalent to the transportation of about 5300 tons, it was found that the -track of the vehicles with 2 ■4-inch tires presented deep ruts, and was too bad for further experiment. The passages of the vehicles with 4" 6-inch and 7-inch tires were continued until the weight transported equalled about 8200 tons, when it was found that there was no difference between the conditions of the two tracks, but both were less worn than, that of the 2 • 4-inch tires, after transport- ing 5300 tons. Thus it appeared that on a strong gravel road a load of nearly 5^ tons on four wheels did much more damage with 2 ■4-inch tires than with 4-6-inch tires, but that there was little or no advantage to the road in having tires beyond the latter width. Some of the stones of which the road was made up took nearly all the bearing, and the weight was not dis- tributed equally over a wide tire. This result entirely confirmed the opinion given by Sir J. McAdam* some years before, that no increase of breadth of tire above 4^ inches is useful, as a greater width cannot at one time touch the surface of a well-formed road. The transport of 8200 tons on 4'6-ihch tires did less damage than 5300 tons on 2 ■4-inch tires, the loads in each case being 5 tons 8f cwt., so that, speaking rouglily, the narrower tires caused double the wear to the road. This is quite in accord- ance with the experience of the excessive wear caused by heavy loads on narrow tires. A load of 5 tons 8| cwt. on four wheels having 2 •4-inch tires gives a pressure of llj cwt. on each inch width of tire, which exceeds by 2^ cwt. per inch that on the wheel of a Pick- ford waggon with 2i-inch tires loaded with 3 tons. With loads not so excessive, although narrow wheels may appear to do no more harm to a hard road than wider ones with the same weight, a close examination of the surface will show that more crushing has taken place. On the 4 ■ 6-inch tires the pressure was at the rate of rather less than 6 cwt. per inch of width, still a heavy load, and exceeding by nearly one-fifth the 5 cwt. per inch which Sir J. Macneill considered should be the maximum load for the generality of roads ; nevertheless, the greater width of * Evidence before Select Committee on Steam Carriages, ] 831. SUKFACE WEAK. 75 tire, 7 inches, reducing the pressure to less than 4 cwt. per inch of width, did not appear to be of any advantage to the road. On a weaker road, the greatest useful width of tire would have been found to have been more than 4 • 6 inches. Instead of the weight being borne, as on a hard road, on a few points, it would have been more equally distributed over the whole tire. Nevertheless, as will be shown farther on, the advantages of a wide tire to carry a heavy load on a soft and yielding road are not so great as might be supposed. The wear resulting from the transport of a given weight was found to be diminished by dividing it on two or more pairs of wheels. About 6900 tons transported in loads of about 36 cwt. on four wheels having 2 •4-inch tires, equal to 3| cwt. per inch of width, produced less wear than when transported in loads of 8 tons on four wheels having 6 • 6-inch tires, equal to 2 tons on a wheel, and nearly 6 cwt. per inch of width. The same weight transported in loads of about 5 tons on two wheels having 6 • 6- inch tires, equal to 2 J tons on a wheel, and upwards of 7^ cwt. per inch, caused greater wear to the road than in either of the preceding cases. When three similar vehicles were loaded with weights pro- portioned to the breadth of tire, equal to nearly 5 cwt. per inch of width, and amounting to about 2 "4, 4" 5, and 6 " 9 tons respec- tively, it was found that the heavier loads on the wider tires were more damaging to the road than the lighter load on 2*4- inch tires, which made 3107 passages — equal to about 7370 tons transported — without producing any trace on the road, while the load of 6 • 9 tons on the 7-inch tires caused far more damage than the 4" 5-tons on the 4' 6-inch tires. A slight trace without apparent disintegration was produced by the transport of 7878 tons in 4 ' 5-ton loads on the 4 • 6-inch tires, while the transport of 6924 tons in 6 ■9-ton loads on 7-inch tires produced well- marked ruts, the bottoms of which were completely disin- tegrated for a thickness of several centimetres. The draught of the vehicle with 7-inch tires and 6 • 9 tons load was found to increase with the number of passages much more rapidly than that of the other two. The draught increased also, but in less proportion, with the 4 • 6-inch tires, while with the vehicle with 76 THE MAINTENANCE OF MACADAMISED EOADS. tires 2 ' 4 inches wide it remained the same. The road was 14 inches and upwards thick, and if it had been thinner and weaker the comparison would no doubt have been still more unfavour- able to the heavier loads on wider wheels. Springs were found to diminish the wear of roads, more especially at speeds beyond a walking pace. Vehicles on springs going at a trot were found not to cause more wear than vehicles without springs at a walk, all other circumstances being the same. The concussions arising from irregularities of surface affect the road as well as the vehicle, and though springs to a considerable extent neutralise concussions, from the way in which they are fixed, they do so much more effectually in a vertical direction than in that parallel to the surface of the road, and it is in the latter direction that concussions are more de- structive to the road-coatiag. Smoothness of surface, even with springed vehicles, conduces greatly, therefore, to diminish the wear from passing wheels, as well as that from horses' feet in consequence of the lessened draught. Wear from Bending and Cross-ireaking. When bending or cross-breaking takes place, there must be a yielding of the subsoil, as well as of the road-coating, under the passing load. The subsoil has always eventually to support the load, and its ability to do so depends on its nature and condi- tion, which can be much influenced by drainage, and on the area over which the load is distributed. The latter depends chiefly on the thickness, but also to some extent on the cohesive strength of the road covering by which the weight is transmitted from the surface to the subsoil. The weight on a loaded wheel, supported on the small part of the road surface ia contact with the tire, is distributed over an area which increases with the depth below the surface, and in such a manner that the pressure on the subsoil is greatest beneath the wheel, and diminishes towards the outside of the area affected by the load. If the subsoil yields, the road-coating yields with it to a certain extent without visible cracking, but it ultimately breaks under the shearing and cross-breaking strains to which WEAR FROM BENDING AND CEOSS-BKEAKING. 77 it is exposed. The road is forced upwards round the depression caused by the loaded wheel, and as the latter moves forward, an undulation of the surface in advance of the wheel may be observed, accompanied by cross-breaking of the road-coating. Along the sides of the hollow track left by the passage of the wheel the elevations of the surface remain as low ridges in which cracks are visible which can be traced towards the subsoil by cutting into the road. These effects may be watched during the passage of a heavy load over a weak road, but to illustrate further the manner in which a road on a weak bottopi gives way under excessive loads, the effects have been reproduced on a small scale by the author with model wheels on a model road-coating composed of parti- ally set plaster on a subsoil of soft tempered clay. The models were one-eighth of real size, but in giving the results it will be convenient to speak of the full size intended to be represented. Thus the wheels represented ]svere, one 34 inches in diameter with a rounded tire If inch wide, and others from 33 to 60 inches in diameter with cylindrical tires 3^, 5J, and 6 inches wide. The road-coatings represented varied from 2 inches to 4| inches in thickness, and were of different degrees of cohesive strength and hardness. When a wheel at rest was loaded until the road-coating began to crack, there was a bulging out of the underside in a roughly shaped oval, and a depression of the subsoU, which beneath the wheel was nearly equal to the depth to which the wheel sank in the surface, and which was surrounded by an elevation of both subsoil and road surface. On making sections, it appeared that, besides smaller cracks, there were two pairs of principal cracks, originating at the edges of the tire, one -pair approximately vertical, and another pair spreading outwards at an angle of 35° to 55° towards the sides of the bulged part of the road-coating. With an increased load the latter cracks extended at about the same angle to the margin of the bulge round the ends of the oval, and an irregularly shaped truncated cone was separated from the rest of the ' road-coating. The area of the base of the conical piece thus, as it were, punched out may be taken to be that on which the load was ultimately supported by 78 THE MAINTENANCE OF MACADAMISED EOADS. the subsoil, and its shape and size was apparently influenced in several ways. The width of the oval depended on the breadth of the tire, the angle at which the cracks spread outwards, and the thickness of the coating they had to traverse before reaching the subsoil. The length of the oval depended on the length of wheel tire in contact with the road, and on the angle of the cracks and the thickness of the coating. Thus the width, other things being the same, was determined by that of the tire, but the length was influenced by the size of the wheel, and also by the breadth of tire. A larger wheel, having a greater part of its circumference bearing on the road, and a narrower tire, by making a deeper and longer impression in the surface, both tended to make the oval longer. Thus a wheel 6 inches wide in the tire and 42 inches diameter ulti- mately rested on an oval area of subsoil 12 inches wide and 16 inches long, containing 153 square inches ; and a wheel of the same width of tire &,nd 58 inches diameter, on an area 12 inches wide and 18 inches long, containing 166 square inches ; the thickness of the road-coating being in each case about 3J inches. A pair of wheels 42 inches in diamete&with the tire of one wheel 3 J inches wide, and of the other 6 inches, when equally loaded, were ultimately carried by a larger area of sub- soil under the narrow wheel than under the broader, in con- sequence of the deeper impression and longer oval made by the narrower wheel. The narrower rounded tire, when the surface was hard enough to prevent its cutting in, was often borne by a considerable area of subsoil, , the cracks originating on the surface of the road around and quite clear of the impression made by the wheel. The influence of the thickness of the road-coating, in increas- ing the area of subsoil over which the load is distributed, becomes apparent if we consider that, if the cracks spread out- wards at an angle of 45°, which is an average inclination, an additional inch of thickness would give an additional inch all round the margin of the bulge and increase the areas above given for a thickness of 3^ inches by nearly one-third for a road- coating 4| inches thick. WEAE FROM BENDING AND CROSS-BREAKING. 79 When a heavily loaded wheel was made to roll forwards, the bulging of the underside of the road-coating moved forward also, and the cracks extending round the margin and meeting in advance of the wheel formed a succession of conical fractures, which were followed up by the more vertical cracks beneath the edges of the wheel tire ; and as the weight came on them, the conical pieces formed by the inclined curved crack in advance were successively broken off by transverse fractures. After the passage of a wheel, the surrounding portion of the road-coating could be removed, leaving a roughly shaped prism slightly embedded in the subsoil, its top being generally the wheel track, its base the subsoil, and its sides sloping outwards at an angle of 35° to 55°. It was divided by numerous longi- tudinal and transverse fractures, in some of which there was considerable dislocation and grinding together of the fragments, and in those cracks which opened downwards the subsoU rose and became mixed with the road material. The surface of the road alongside such a wheel track, even if apparently uninjured, would of course be undermined and weakened by the loss of support from the prism-shaped piec^e forced downwards under the wheel, and loads which the road could have borne before would be quite sufficient to cause further damage. This is often proved by experience ; the single passage of a heavy load does apparently little harm, but repeated passages soon tell on a road. The way in which thickness of road-coating increases the area of subsoil over which the load on a wheel is distributed has been pointed out. It has of course also an important influence on the intensity of the pressure of the load on the subsoil which is independent of the width of the tire ; and other considerations tend to show that the weight per inch of width of tire affords no true measure of the pressure on the subsoil. Assume the weight on a tire 4 inches wide to be 5 cwt. per inch of width, and to be distributed over an oval 16 inches long and 10 inches wide, con- taining 138 square inches. By adding 2 inches of width to the tire, loaded as before with 5 cwt. per inch, the breadth only of the oval bearing on the subsoil will be effected, and it will be increased by 2 inches, and the area by 2 x 16 = 32 square 80 THE MAINTENANCE OF MACADAMISED ROADS. inches, or less than one-fourth, while the load on it would be 30 cwt. instead of 20 cwt., or one-half greater. There is reason to suppose further that, when tires are loaded in proportion to ■their width, the pressure on the subsoil is greater immediately under the wheel with wider tires, though to what extent it is difficult to say.* Another most important point is that wide tires cannot bear uniformly on a road, and a large proportion of the whole weight on a wheel is borne on a small part of the surface and a proportionately small area of subsoU. When weak and yielding roads are concerned, it is the load on the subsoil, and not on the tire of the wheel at the surface of the road, that should be considered, and that depends far more on the total weight on the wheel than on the weight per inch of width of tire. It is plain both from experiment and observation that on roads of all descriptions it is the passage of heavy loads that causes the greatest injury, and that even on strong thick roads an increase of breadth of tire in proportion to the heavier load does not prevent a considerable increase of wear, while on weak, yielding roads an increased width compensates still less for an increased load on the wheel. The observed effects of heavy traction engines, and the trucks , drawn by them, illustrate this. A reference to the tables of weights before given (p. 67) will show that the loads per inch * If a road-coating be supposed to be made up of smooth spheres of the same size, each sphere pressing equally on four spheres underneath it, it can be shown that the area over which a weight on the surface is distributed increases with the- depth below the surface, the portion affected spreading out on aU sides at an angle of 54° 44' with the horizon. The area over which the fuU surface pressure is borne decreases with the depth, at the same angle of 54° 44', so that at a depth from the surface of rather more than two-thirds of the width of the loaded area no part of the road-coating would sustain the full surface pressure ; and at a depth equal to a little more than li of the width of the loaded area of surface the pressure at the centre would not exceed three-quarters of that on the surface, and would diminish towards the edges of the area affected. Unequal-sized spheres under the conditions here supposed would somewhat modify the result, and the cohesive strength in a road-coating, and sinking of the subsoil, would also have some effect, but it appears probable from experiments that it is very much after this manner that the load is distributed through a road- coating to the subsoil. If so, when tires are loaded in proportion to their width, the depth to which the full surface pressure extends is about two-thirds of the width of the tire. LOAD ON THE SUBSOIL. 81 of width of tire in the case of ' traction engines and trucks are less than in the case of many waggons, carts, vans, and coaches, though the weight on the wheels of the former may be three or foul times as great. Experience, however, shows that roads which are able to bear heavy coaches and waggons with 6 or 8 cwt. of load per inch of tire, with no injury beyond some crush- ing of material at the surface, are squeezed out of shape and broken down by the heavy engines with far less weight per inch of width of tire. When heavy loads are carried on narrow tires, the damage is far greater on all roads, but more particularly on those that are weak from want of thickness or a yielding subsoil. This cause of excessive wear has long been recognised. When the wear is chiefly confined to the surface the crushing action of heavy loads on narrow tires is such that only the strongest materials can resist, and when, besides, there is cross-breaking of the road-coating, the wear is largely increased. Unfortunately, excessive weights, whether on broad or narrow wheels, come upon roads without any reference to their strength to bear them. It often happens that a road on a weak foundation, kept in a good state of repair, will stand the weather and carry a certain traf&c for years with a material not very strong, and of a thickness, though small, sufficient for the traf&c, showing no signs of weakness, and presenting a hard, ssaooth surface to which the wear is almost entirely confined. But should exceptionally heavy traf&c, such as hauling of timber or building materials, or a traction engine, come upon it, and tax it beyond its strength, it will at once suffer, perhaps only to an extent which is not noticed except by the surveyor, but which demands a large increase in the outlay for maintenance ; or it may be cut up and destroyed to such an extent that repairs become more of the nature of reconstruction than of ordinary maintenance. As much material may be required in a short length as would have been enough for the maintenance of a mile or more of the road with its former traffic, or of a road originally stronger under the heavier traffic. It may be, and no doubt it often is, the case that better drainage of the subsoil would have enabled the road to resist 82 THE MAINTENANCE OF MACADAMISED EOADS. the action of the heavier loads, and the importance of drainage cannot be too much insisted upon. But the least thickness of road required on a naturally bad bottom is only learned by experience, and a surveyor will naturally suit the strength of his road to its situation and traf&c, strengthening those parts that show signs of weakness, by successive additions of materials, until they are well able to bear the traffic, and the road has a certain reserve of strength ; but he wlU not incur useless expenditure by putting on more materials than the traffic requires, or can work in without inconveiliencing the public, to provide strength for heavy loads that may never come on his road. Action of the Weather. The weather acts to some degree directly on the materials, but to a much greater extent indirectly, by increasing the wear from the traffic. Frost expands the moisture in the crust of the road, and perhaps in the road material itself, and when the thaw comes, a general disintegration takes place, converting the sur- face into a stratum of loose materials into which the traffic cuts, and the surface water soaks'. Wet weather, by softening the muddy binding matter, which, as it has been already shown, forms so large a proportion of the best road-coatings, destroys the solidity and coherence of the road, rendering it less capable of supporting the traffic, and increasing the wear from crushing and rubbing together of the materials. Eain following frost and thaw is very damaging, and alternations of these, frost returning when the disintegrated surface has been saturated by rain, will break up the thickest road-coating if the surface is once destroyed, and the drainage be defective. Violent rain on exposed situations, especially where the materials are silicious, washes out the binding portion, and often the smaller stone as well, leaving the road loose and porous. On hiUs the scouring of the surface, from water break- ing out of the side channels in heavy rains, causes great damage. The amount of materials washed away from the surface, and ACTION OF THE WEATHEE. 83 even from the body of a neglected road, is often much greater than that fairly worn out by trafi&c. Excessive dryness has the effect of loosening the surface of roads made of siLicious materials, the detritus of which has little or no binding property when dry. The extent to which these various effects may be injurious will depend on the nature of the road materials, on the drainage, subsoilj situation, and on many other accidental circumstances. Frost and thaw have but little effect on a dry, well-kept road, especially when, the materials are igneous or sUicious. A limestone road will always suffer more, and severely if, owing to its situation or bad drainage, it holds the wet. When the frost is severe enough to reach the subsoil, if it be boggy or wet, the road-coating wiU be blown up from the bottom, whatever be the nature of the stone composing it. On a chalky subsoil great injury is often done on the breaking up of frost, whatever may be the material of the road or the care taken of its drainage and general condition. On a road subjected to cross-breaking and cracking arising from traffic beyond its strength, aU atmospheric causes of wear are greatly aggravated. Earn and frost easily penetrate it, and through it to the subsoil. Heavy traffic coming on a road disintegrated by frost or softened by wet increases enormously the mischief originally caused by the weather. Hedges and fences which obstruct the sun and wind, hinder the road from drying, so that a road sheltered by trees or high hedges is always softer, and more liable to be injuriously acted upon by the weather and the traffic, than one well exposed to the sun and ah'. Trees have been supposed to add 25 per cent, to the cost of maintaining, a road, and high hedges, especially on the southern side of the road, are very injurious, particularly on a heavy clay soil, or where drainage is imperfect. G 2 84 THE MAINTENANCE OF MACADAMISED EOADS. Circumstances which influence Wear. The amount of wear from every cause depends, of course, largely on the nature of the road material. Materials of a fairly good quality, such as flints or hard field stone, wear two or three times as fast as Guernsey granite, whinstone, and other traps and basalts ; and when the material is weak and the traffic heavy, the wear may be four or even five times as great as it would be with the best material. Generally speaking, the wear from every cause is less in proportion as the road is kept in good condition as^ to surface, solidity, thickness, and drainage. It is less on slight gradients than on a dead level, because of the better drainage, but on hills it is increased by the use of skidpans or drags, and from the effects of running water. The surface on a hill is washed clean, and looks better than the fiat below on to which the mud is carried down, and this often leads to the neglect of a hill until it is worn down to the rough bottom stones. There is more wear in winter than in summer, in wet situations than in dry, and where sheltered by hedges and trees than where open to the sun and air. When traffic follows in the same track, which it has a strong tendency to do, particularly where the surface is soft and the tracks are visible, there is a great increase of wear. ( 85 ) CHAPTEK VII. MEASUEEMENT OF TRAFFIC AND WEAR. CONSUMPTION OF MATERIALS. Measurement of Traffic and Wear, In experiments like those of Morin, vehicles with loads well ascertained were employed, and the amount and nature of the traffic which caused the wear were accurately known. Un- fortunately, any measure of the ordinary traffic on roads can only be obtained with difficulty and imperfectly. In France, the number of "collars," or animals drawing loads, was formerly counted, four animals drawing empty vehicles being counted for one collar. The imperfection of this way of reckoning traffic is evident. All draught animals rank alike, whatever loads they are drawing, so that two horses with three tons on one pair of wheels count for no more than a pair of ponies in a light carriage, though the wear they occasion is many times as much. Horses not drawing, cattle, sheep, &c., are not taken into account at all — in some districts an important omission. Afterwards an account was taken of the weights carried as well. In 1876, the mean daily number of collars counted in this way on all the national roads was 156, and the average daily weight 182 tonnes,* ranging from 1159 collars or 1589 tonnes in the department of the Seine, to 100 collars and tonnes or even less in some departments. In 1882 a new plan was adopted ; vehicles were counted in three categories : — (1) those loaded with produce and merchandise ; (2) those used for the transport of travellers, and (3) private carriages and empty vehicles. Animals not drawing were counted, and the value to be given to them and to empties in " collars " was left to the engineers. The gross and net weights of the vehicles were also ascertained, and the traffic on all the national roads is now given in " collars " • Tonne = 2205 lb. 86 THE MAINTENANCE OF MACADAMISED EOADS. and in " tonnes " per day. The traffic is indicated on a map by a band along the roads proportionate in breadth to the traffic. In taking account of traffic in South Wales, under the author's direction, the light collars drawing carriages, &c., paying a higher toll, were kept distinct from the heavy collars drawing carts and waggons ; and horses not drawiag, cattle, sheep, &c., were valued at fractions of collars in rough pro- portion to the toUs payable on them. The object of this was to arrive at a value, in collars of traffic, of the tolls paid at the various gates, as well as to separate the light and heavy traffic for the purpose of estimating the wear. Where, as in a street, the traffic is so considerable that it is spread nearly uniformly over the whole width, the width of the road must be taken into account, though in the most crowded streets the traffic is greater in the middle than at the sides. Mr. Deacon, in measuring traffic in the Liverpool streets, ascer- tained : — (a) The tonnage passing over the carriage-way in twelve months. (h) The width of the carriage way. (c) The number of wheels on which the traffic in borne. Thus r = the weight of traffic per unit of width, and - = the number of tons per wheel.* c A method adopted in London by Mr. Howarth, consists in obtaining the average weights per unit of width, by observations taken for half hours at iixed periods throughout the day of 16 hours, from 7 a.m. to 11 p.m., and repeated at the same points on different days, and in different conditions of the weather. The traffic on some of the principal macadamised thoroughfares of the Metropolis in November, 1878, as thus ascertained, may be given, though wood pavement has since superseded the macadamised surface. The average weight per wheel was 0*26 tons in Piccadilly and • 30 tons in Parliament Street.t * Proo. Inst. O.E., vol. Iviii. p. 21. t Ibid., p. 33. MEASUREMENT OF TRAFFIC AND WEAR. 87 Average Number of Vehicles per day of 16 hours. Gross Weight. Average per Vehicle. Average Width of Eoadway. Weight per foot of Width. Kegent Street . . PiocadUly .. Parliament Street Victoria Street.. 10-796 10-776 14-306 6-040 tODB. 9,668 9,358 14,380 5,780 tons. 0-900 0-868 1-005 0-957 feet. 52 37 45 40 tons. 186-0 252-9 321-7 144-5 The difficulties in the way of measuring the ordinary wear of roads are considerable. M. Bardonnaut, M. Dupuit, and other Trench engineers, have endeavoured to deduce the wear arising from traffic to a certain extent known by measuring the amount of detritus collected in the form of mud or dust. Many precautions are necessary to avoid measuring matters not proceeding from the wear of the part of the road under experiment, and to prevent the loss of any part of the detritus by its being washed away by rain, or blown away, and it is only in special circumstances that the results can be thoroughly relied on. Cross sections of the surface carefully taken at the same points at intervals of time, sometimes combined with soundings or pittings to measure the thickness, have been employed both ^in France and in England, as a means of ascertaining the wear. It is not, however, enough to measure the wear, as shown by loss of thickness ; regard must be had as well to the composition of the road-coating. One result of wear is that materials are consumed and removed from the surface as mud or dust, another result is a breaking up and grinding down of the stone remaining in the road, so that the proportion of detritus to stone increases as wear goes on. The variation in the proportion of stone found in different specimens of road- coatings has already been pointed out, and it is stated* that a road in good order, of the same materials, and exposed to heavy traffic, may contain proportions of stone above 2 centi- metres (=0*8 inch) in diameter, varying from 87 to 37 per cent. To ascertain, therefore, aU the effects of wear, it is * Annales des Fonts et Chaussdes, vol. vi. 1853. 88 THE MAINTENANCE OF MACADAMISED EOADS. necessary to learn how far the proportion of stone to detritus has diminished, and how far it has been maintained by the addition of fresh materials. The process adopted for this purpose by the engineers of the Ponts et Chauss^es is as follows : Trenches are cut across the road, and, from the thickness observed, the 'quantity of materials which the road-coating represented is deduced, regard being had to the relative bulk of new materials and of con- solidated road. The contents of the trenches are sorted into stone above 2 centimetres ( = • 8 inch) in diameter and detritus below that size, and the proportions are noted. After an interval of several years, during which the quantities of fresh materials laid are carefully recorded, the same process is repeated. A comparison of the quantities of materials in the road at the two periods, making allowance for the fresh materials which have been added, gives the quantity consumed by wear and removed as mud or dust in the interval, and the proportion of stone and detritus at the beginning and end of the trial shows to what extent the road-cutting has deteriorated or improved in composition. The traffic must be observed also, if any deductions as to the amount of wear caused by traffic are to be attempted. By observations and experiments of this sort the French engineers have endeavoured to ascertain the actual wear of roads, and its relation to traffic as measured by collars and by tonnage. Some engineers have maintained with M. Dupuit that the wear increases in the same proportion as the traffic when the nature of materials and other circumstances are the same, while others have contended that the wear increases in a much greater ratio than the traffic. It is probable that with ordinary traffic the former view may be not far from the truth, but when the loads represented by collars are different, it must obviously be otherwise if, as is undoubtedly the case, heavy loads cause more wear than light ones, even when the same total weight is transported. An instance is recorded * of two pieces of the same road * Annales des Ponts et Chaussdes, vol. vi. 1843. MEASUREMENT OF TRAFFIC AND WEAR. 89 maintained with materials of the same quality, on one of which, where three-quarters of the traf&c consists of very heavy loads, the consumption was ascertained to be 287 cube yards per mile, while on the other piece, where one-quarter of the loads were heavy, and the rest light or empty, it was only 81 cube yards per mile per annum for a mean daily traffic of 100 collars. In this case the wear of 100 collars of heavy traffic was three and a half times as great as that of the same number of collars with light loads. The effects of an iacrease of traffic measured by tonnage on the wear of materials are illustrated iu a memoir by Mr. Graeff.* Owing to the falling iu of the Saint-Etienne tunnel, the traffic on a road was suddenly increased from its usual amount of 1378 tons per day to 2264 tons, 3150 tons, and to 5315 tons on different portions, at which rates it continued for 74 days, after which it fell on all the portions of the road to 1772, tons per day. The consumption of materials, i. e. the amount removed from the road, and that reduced to detritus below 2 centimetres in diameter, was measured iu the manner which has been above described, and the results were as follow : — Daily Traffic. Annual Consumption of Materials per Mile. Annual Consumption per Mile per 100 Tons of Daily Traffic. Tons. 1378 Cube yards. 724 Cube yards. 52 1772 1857 104 2264 2780 122 3150 4615 146 5315 9886 186 These figures show a nearly uniform iacrease of wear, at a much higher ratio than the increase of tonnage, less than four times the traf&c, measured by tons, consuming more than 13^ times the quantity of materials. The case was no doubt an extreme one. The road was from 20 to 23 feet wide, and 5315 tons per day represents 250 tons per foot of width, in this case carried mostly in heavy loads on narrow wheels. The material * Annales des Fonts et ChausB&s, vol. ix. 1865. 90 THE MAINTENANCE OF MACADAMISED EOADS. was schist, the subsoil clay, and the thickness of the road-coat- ing, which was less than 9 inches at the outset, appears to have been only 7i inches under the heaviest traffic. All the condi- tions were thus unfavourable. Both in the nature of the material and in thickness, the road was altogether insufficient for such a traffic, and the annual consumption of materials was equal to a thickness of more than IJ inch over the whole surface, before the excessive traffic was thrown on it, and under the traffic of 5315 tons per day the consumption was at the rate of more than 2 feet of thickness in a year. On another part of the same road, with the same material, where the wear was measured by the loss of thickness on the surface, an increase of traffic from 1200 to 1500 tons per day caused an increase of wear from 464 to 896 cube yards per mile per year, or from 38 to 60 cube yards per 100 tons of daily traffic, or an increase of traffic in the proportion of from 4 to 5 nearly doubled the wear. It will be unsafe to draw any general conclusion as to the increased rate of wear from these cases. There is no doubt that when the road or the materials are too weak for the traffic the wear is augmented, and that it increases enormously when the limit of strength either of the road material or of the road itself is approached. Here both limits must have been nearly reached before the exceptionally heavy traffic was thrown on the road. The observations at Saint Etienne, by M. Graeff, appeared to ehow that with an equal traffic the wear of materials increased with the proportion of detritus in the road, and in a more rapid ratio, and that with greater traffic the rate of increase of wear appeared to be more rapid. This would probably have shown itself in a more marked way if, instead of considering everything under • 8 inches diameter as " detritus," a much smaller gauge had been adopted. Consumjotion of Materials. The annual wear of a road as measured by thickness has been seldom found in France to exceed J inch, or on the most fre- quented roads 1 inch, and to be not more than |^ inch on roads CONSUMPTION OF MATEEIALS. 91 10 or 12 feet wide, with an average traffic of about 30 collars per day. Several observers agree in considering about 100 cube yards per mile per year to be an average consumption of good silicious or calcareous materials by 100 collars of traffic per day. Some give as little as 58 cube yards per mile for quartz gravel, 43 cube yards for muschelkalk, and 33 cube yards for granite gravel,* and 65 cube yards per mile is stated to be the consumption of a middling silicious material by 100 collars per day of the light carriage traffic of the Avenue Neuilly, Champs-Elys^es.f The average consumption of materials on all the national roads of France in 1869, and in 1875, is stated to have been at the rate of 49^ cube yards per mile per annum for 100 collars of daily traffic. :t In 1876 it appears§ that the mean consumption of materials on the whole of the national roads of France was 78 cube yards per mile, being at the rate of 53 cube yards per mile per annum for every 100 collars of daily traffic, and 50 cube yards per mile per annum for every 100 tons carried daily. In the different departments, the average quantity of materials per mile of road varied from 22 cube yards in Corsica to 390 cube yards in the department of the Seine, seldom falling below 40 cube yards, or exceeding 150 cube yards per mile. The consumption per 100 coUars and per 100 tons of daUy traffic was generaUy below the averages above given when the traffic was considerable, and this is very observable in those departments where the traffic was very heavy. The influence of the weather is shown by the high average consumption of materials compared with the traffic in some departments where the traffic is small, and the effect of a good material is also observable in a small con-, sumption under considerable traffic where igneous rocks were used. There are no means of knowing, even approximately, the * Annalea des Fonts et Chauss^es, 1834, vol. viii. p. 190. t Crinier, Annalea des Fonts et Chauss^es, 1843. X Annales des Fonts et Chaussdes, 1869, vol. xviii. p. 366 ; 1877, vol. xiii. p, 229. § fitat indiquant la Dtomposition par Departement des D^penses d'Entre. tien dee Routes Nationales en 1876. 92 THE MAINTENANCE OF MACADAMISED EOADS. quantities of material used on the roads of England, whether turnpikes or highways. It is impossible from the returns made of annual expenditure even to get at the cost, and information of any kind on the subject is almost entirely wanting. The number of cube yards of materials per mile usually required for the annual repairs of the Glasgow and Carlisle road constructed by Telford are stated* to have been from 60 to 120 cube yards per mile on different parts of the road, the material being whinstone ; and on the the Holyhead road, 96 cube yards per mile in Anglesey, 73 cube yards per mile between Bangor and Cernioge, and 162 cube yards per mile between Cernioge and" Chirk, where the materials were softer, were used for repairs in 1835. t The annual wear of the macadamised streets of London has been given as from 1 inch to 4 inches in thickness of granite coating, and as much as 5| inches on Westminster Bridge, and that of the streets of Birmingham as on an average 2 inches, in some cases as much as 4 inches, and in one street nearly 6 inches of hard pebblestone, ragstone, and basalt (Hartshill stone). J It is doubtful whether the wear was measured, and what is given as such is probably the thickness of materials laid. On the Metropolis Eoads north of the Thames, which up to 1864 comprised about 121 miles of the main roads through the suburbs of London, extending to Hounslow, Uxbridge, Harrow, Edgware, Hampstead, Highgate, Enfield, and Snaresbrook, an average of from 470 to 580 cube yards per mile of granite, hard stone, flints, and gravel was used annually. On the 53 miles of these roads lying within the district of the Metropolis Local Management Act,, 650 to 700 cube yards, principally of granite, were used annually per mile. After 1864, when the latter roads were given up to the parishes, the average on the 67 miles of road which remained was from 380 to 470 cube yards per mile per yeair of granite, hard stone, gravel, and flints. In the county of Edinburgh, where 441 miles of turnpike * Life of Telford, p. 485. t Mr. Provis'a evidence, Select Committee on Turnpike Trusts, 1836. X Proc. Inst. Civil Engineers, vol. xii. p. 228. CONSUMPTION OF MATEEIALS. 93 road were kept in excellent condition under one management for many years, the following average quantities of syenite, trap, and whinstone were used annually : — In the Lasswade district 41 cube yards per mile. „ Dalkeith and Post Eoad district 98 „ „ „ Cramond district 170 „ „ „ Calder, Slateford, and Corstorphine district 67 „ ,, The quantities varied considerably on different portions of road ; while near Edinburgh 500 or 600 cube yards per mile were used, 15 or 20 were enough for remote country districts. In South Wales, where the turnpike roads were under an uniform system of management from 1845 to 1882, the quantities of materials used on about 86 lengths of road, amounting in all to about 1000 miles, have been recorded in the quarterly returns made by the surveyors, and form the best data which as yet- exist in this country for judging of the amount of materials required to keep roads in good order under different conditions. In Glamorganshire, in the suburbs of Swansea and Cardiff, the traf&c is that of the streets of large and busy seaport towns. On one mile at Swansea, 500, 600, and 800 cube yards of materials, consisting of copper slag and mountain limestone, were spread for many years in succession on a road 8 yards wide, having a traffic of about 550 collars per day with very heavy loads ; 600 cube yards per mile would give a coat of an average thickness of 1 J inch of unconsolidated materials for the whole width and length, and represent about 1 inch of consoli- dated road surface. At Cardiff 800 to 1000 cube yards of lime- stone per mile were used for many years on a road of the same width, giving a greater average thickness of coating. These large quantities of materials were only required for a mUe or two, and the rate soon feU to 200 and 150 cube yards per mile. The average on the whole 235 imles of turnpike roads in Glamorganshire was about 110 cube yards of materials per mile, many miles having been maintained with 60 cube yards, and some roads at as low a rate as 30 cube yards per mile. In Carmarthenshire, the average on 290 miles of road was 94 THE MAINTENANCE OF MACADAMISED EOADS. during ten years, 73 cube yards per mile ; some lengths of road having req[uired upwards of 200 cube yards, while other roads were kept well with 20 cube yards, but the majority being nearer the average of 73 cube yards per mile. In Pembrokeshire, the average on 85 miles of turnpike road was 64 cube yards per mile, one road requiring 120 and all the others from 90 to 40 cube yards per mile. In Cardiganshire, the average on 134 miles was 58 cube yards per mile, varying on different roads from less than 20 to upwards of 100 cube yards per mile. In Breconshire, the average on 127 miles of turnpike road was 51 cube yards per mile, varying on different roads from 30 to 100 cube yards per mile, and exceeding 200 cube yards per mile on a short length. In Eadnorshire, the average on 130 miles was 48 cube yards per mile, the quantities on different roads varying in a. corre- sponding degree. The materials consisted of carboniferous, silurian, and lias limestone, coal-measure sandstone, the grits and slates of the Silurian rocks, and very largely of river and field stone. Igneous rocks are obtained only in small quantities in Eadnor- shire and Pembrokeshire. Copper slag has been used either alone or with mountain limestone in the neighbourhood of Swansea. On some of these roads the traffic is light, and on many of them more materials would have been used if the funds at com- mand had permitted it. Though the strength of the roads was in these instances suffered to fall below what was desirable, they were kept in very good condition with the amounts of materials stated above. ( 95 ) CHAPTEE VIII. SPREADING KOAD MATERIALS, New materials may be added to a road either in thin coats and small patches year by yeat, or in a thick coat consolidated by rolling. In the first method the wear is replaced annually, and the traffic is depended upon to work the materials into the road. Where the traffic is not excessive this can be accomplished under proper management with excellent result, and at no serious in- convenience to the public. Considerable care in the use of materials is necessary to ensure their proper application. Sixty or 70 cube yards per mile amount to less than J inch of consoli- dated road surface, supposing the materials to be spread uniformly over a mile of road to a width of 4 or 5 yards. It is impossible so to spread it, even if the wear were so uniform over the whole surface as to render it desirable. A cube yard of stones broken to a 2-inch gauge, when carefully spread, will cover 30 square yards, so that 60 cube yards would only coat about a quarter of a mile 4 yards wide, or 70 cube yards a quarter of a mile 5 yards wide. With such quantities each part of the road would be coated once in four years, and it must have sufficient strength to stand the wear of four years without being coated. If only 30 cube yards per mile of materials were used, it would be eight years before every part of a road 4 yards wide were covered, and the road must be able to undergo eight years wear without giving way, while waiting the turn for each part to be coated. In actual practice both the wear and the thickness of roads is irregular, and if large pieces of the surface of a road on which the wear is small, and the quantity of materials to be laid is limited, are coated all over, it is tolerably certain that thickness is added to perhaps one-half or two-thirds of the area which is already thick enough to bear the traffic, while other parts. 96 THE MAINTENANCE OF MACADAMISED EOADS. including weak places, must be left until their turn conies to be coated, which, may be as jusf shown, from four to eight years. The ordinary wear on weak portions thus neglected is consider- ably greater than it would be on a stronger road, and if from the effects of heavy traf&c or bad weather they break up, the extra quantity of materials required for their repair may be very large. Instead of thus always contending with a road which is in many parts too weak, the irregularity of wear and of strength in different parts of the coating and the consequent reserve of strength in some parts of the road should be taken advantage of. Materials should be laid only on the places that require them, and the whole road should be brought as far at practicable to a uniform strength throughout. Thus no part of the surface is neglected and no materials are wastefully applied to portions already quite thick enough to stand the traffic, and a better road is obtained with a less expenditure of materials. In laying on new materials, the old-fashioned way of waiting till the road has lost its shape, and then spreading a thick coat over a large Surface and leaving it to be worked in by the traffic without further care, should never be followed. A good deal of the new material is thus wasted by being ground up and crushed before it is consolidated, and when at length, and afc great inconvenience to the traffic, consolidation has been effected, the surface of the road will be left irregular and out of shape. The materials necessary to replace the wear of any ordinary traffic can be laid. in comparatively small quantities, where hollows or weak places appear, or where requii-ed to keep the cross section of the road in good form. If they are laid in small patches, and with care, the inconvenience to the traffic will be scarcely perceptible. It should be remembered that until the newly laid stones are consolidated, the operation is not completed, and if the task of working them in is left to the public, it is only right that the process should be rendered as easy and speedy as possible, by good arrangement and care in laying the materials, and by attention to them after they are laid. On a road maintained in good repair on a good system, SPREADING EOAD MATERIALS. 97 there are no holes or ruts or long hoUows worn by the wheels or the horses' feet, but only irregular depressions or " slacks " of the surface, which show where fresh materials should be applied. They are more or less rounded and undefined in out- line, less than an inch deep in the middle, and shallowing gradually towards the edges. Considerable care is required in determining the size and shape of the patches of materials to be laid to repair these hollows, as both a good result and economy of materials and labour depend upon it. Unskilled labourers are inclined to lay stones in rectangular patches, with more regard to the neat appearance of the newly laid stones than to the needs of the road. Parts of the round or oval-shaped hollows must thus be left uncovered, or fresh materials must be laid where they are not required. The angles of a square patch are, besides, very liable to be knocked away, and if the stones are not wasted in this way, they do not set so quickly as if laid in a rounded form. If the ends of a patch be made in the form of an oval more or less pointed, the traf&c will wear it in from the sides, and on a hill the water will be diverted towards the sides of the road, instead of running into the stones, as it does with a square-ended patch. Care should be taken to cover the whole surface of a hollow, so as to leave no place where water may lodge. The object should be to give the surface, after the consolida- tion of the new materials, as nearly as possible the regular form due to the cross section of the road. With stone broken to the usual gauge, and giving a thickness of J inch to 1 inch of con- solidated coating, this can only be done approximately and by using the smaller stuff at the edges, and requires a good deal of aptitude on the part of the roadman. The patches seldom need be more than 3 or 4 yards long and 2 yards wide. Too many hollows on the same part of the road should not be covered at once, the deepest may be coated first, and when the stones have partly set, the shallower ones may be attended to ; and if, mean- while, the water lodges in them, it may be led off by cutting small grooves with the pick. It is generally easy to leave a winding track along the road free from stones, by arranging patches sometimes on the H 98 THE MAINTENANCE OF MACADAMISED EOADS. sides, and sometimes on the middle, so that the horses' feet may avoid the stones, which will be worn in from the sides of the patches by the wheels. When this has been partially effected, other patches may be so laid as to divert the trafl&c into another track. The curious tendency of horses drawing vehicles to follow in the same track must be checked by inducing them by means of small patches to change the track. This, of course, must be done with due regard to the places that require strengthening, and demands more contrivance than is to be expected from an ordinary roadman, unless trained by the surveyor. If, from neglect or bad management or other cause, long ruts or large hollows have been allowed to form, they should be repaired in short lengths, and one part at a time. Vehicles avoid long strips of stones laid in a hollow worn by wheels, and soon make another rut alongside. Laying a long strip of materials on the middle of the road diverts the traffic to the sides, which are sure to suffer a good deal, and may be entirely cut up before the stones in the middle are worked in. If, after all hollows have been covered, there is still material that ought to be laid, it should be spread in sheets one stone thick over the whole width of the road, up to, but not including the water- tables. The sheets should not be more than 6 or 8 yards long, and with intermediate lengths at least two or three times as long as the stoned portions, and when the stones first laid have worked in, other patches may be laid in the intermediate spaces till the whole has been covered. On steep hills, coating from side to side is an unnecessary inconvenience to traffic. One side should be coated first, and the other left until the stones are partially consolidated by the descending vehicles. A thick coatiag of metaUing should never be laid on; a layer one stone in thickness, the stones being laid sufficiently close to support each other, is almost always enough, and if not, one layer put down upon another when it has almost worked in will give any thickness required. The practice of using trestles, logs, or stones to force the traffic over newly laid stones to work them in is one to be avoided. It is generally but a clumsy way of doing that which can be accom- plished by good arrangement in laying materials, and by after SPEEADINQ EOAD MATERIALS. 99 attention to them. The legal right to use trestles on highways has been held to exist, though it has been disputed. That materials may be spread in small quantities, they should be at hand in depots or heaps, from which they can be wheeled out by the roadman as he requires them. There is generally no difficulty in arranging this; room can almost always be found on the roadside for stone depots or heaps about 100 yards apart, when the distance to be wheeled will never exceed 50 yards. Stone should be kept in reserve on the roadside, so that it may not be necessary to deposit small heaps at short intervals every year, when the consumption is small. If there are no places for stone heaps, or depots, close enough together for the materials to be wheeled out, carting must be resorted to, either by contract, as one of the conditions of the supply of materials, or, preferably, by the hire of a horse and cart ; and it will be necessary to guard against waste by spreading too large quantities in one place, and carelessness in laying the materials. When a hard and costly material is used in considerable quantities, it may sometimes be spread with advantage under the direction of a special man, instead of being left to the care of the road labourers. The latter, of course, assist in the spreading, and in this way one skOled man may superintend the spreading of materials over a long length of road. The practice of picking up or loosening the surface of a road with a pick, sometimes called " stocking," in order to make the new materials unite more readily with the old surface, is one on which opinions have been divided siace the days of McAdam, who appears to have recommended it, while Sir H. ParneU and Mr. Provis, speaking from the experience of the Holyhead road, condemned it as expensive, wasteful of the old materials, and of no good whatever to the road. On thin roads it is certainly almost impossible to pick up the surface without destroying the cohesion of the whole coat, thus doing far more harm than any benefit arising from it can compensate for. On thick roads with a hard surface, a proportion of stones may be crushed and wasted before they can be incorporated in the road, and picking up may be useful, but stones properly laid in moist weather generally 11 2 100 THE MAINTENANCE OF MACADAMISED EOADS. bind sufficiently well on ordinary roads without any picking up, as tlie weak places, or hollows, where patches should be laid, have softness enough to render the working-in easy. At the most, a slight loosening of the surface round the margin of the patch is required to give the stones a hold, and hasten the setting. On roads of considerable thickness, where the surface is hard and the material tough, there is no danger of breaking up the whole road, and a quicker consolidation may be worth obtaining at the cost of the extra labour, and even of some of the old materials. Loosening to about J inch in depth, and rather more round the edges, is sufficient for small-sized metalling. The tendency of workmen is to pick up too deeply, and it is unavoidable when full-sized stones are disturbed in their bed. Picking or stocking up the surface before laying fresh materials generally costs from ^d. to Id. per square yard. The use of a binding material in road maintenance, when materials are applied in thin coats and smaU patches, is seldom necessary or desirable. The road has already in it more than enough small stone and detritus to fill up all interstices, and in the damp weather in which stones should be laid there is generally little difficulty in getting a layer one stone thick to work in without adding any binding. On a road from which the mud is constantly removed, the places where fresh materials have been laid often appear, after the stones have worked in, as muddy places. So long as the materials remained uncon- solidated, the mud forced out as the stones worked in could not be scraped off. It would evidently be a mistake to add unneces- sarily to this excess of detritus in the road, and on the contrary it is generally right to scrape the road before laying down fresh materials, as a layer of mud hinders the incorporation with the road surface. When large sheets of stones have to be laid in a street or road of great traffic, the use of a binding will ease the traffic and cause the new material to consolidate more quickly. A good clean binding material must be used, and evenly spread, and in dry weather watered. Too much binding, or a material of a muddy character^ will make the road soft and weak until the excess has been removed by scraping or sweeping. SPREADING EOAD MATEKIAiS. 101 On a mountain road with light trafl&c, exposed to heavy rains and sweeping winds which remove all mud and detritus, a bind- ing material may be used with advantage, especially with sUicious materials. The consolidation of materials after they are spread can be greatly aided by attention on the part of the roadman. The sooner they are consolidated the better they will wear, and a little care bestowed on newly laid patches will save much work and materials afterwards. If too many stones are laid down at once, the roadman cannot give them the necessary attention, and they do not become consolidated so quickly or so well as if they are spread in quantities that can be properly attended to. Euts, which always have a tendency to form in freshly laid materials, especially if more than one stone thick, should be effaced by raking across backwards and forwards, and this requires more skill than may be thought necessary for such a simple operation. Everything should be done to distribute the traffic equally over the whole breadth, and prevent the formation of ruts by vehicles following in the same track. However carefully patches are laid, stones, especially round the edges, will be displaced ; they should be put back, as single loose stones are dangerous to the traffic, hurtful to the surface of the road, and liable to be crushed and wasted as material. If consolida- tion does not appear to commence, a little smaU stuff from the clearing up of the side channels, or road scrapings, may be applied as a binding material, especially round the edges of the patch, where the old surface may also be slightly loosened with the pick. It is the practice in France to aid consolidation by ramming the new-laid stones with a pounder, 15 or 20 lb. weight ; the effect is good, and it is sometimes very useful, but it is not generally worth while to incur the cost of it. In dry weather, when a dangerous hollow has to be repaired, and stones laid in the ordinary way will not set, a sort of concrete made of five parts of small stone and one part of road scrapings, mixed with water into a stiff paste, may be put on, after picking up and watering the old surface. When it has dried a little, the patch should be rammed or beaten, and be covered with a thin 102 THE MAINTENANCE OF MACADAMISED KOADS. coat of dry small stones, over which detritus, should be spread, and the ramming or beating should be repeated. Smoothness of surface of a road is generally a proof that the materials have been carefully applied and raking in and scraping have been properly attended to, though hardness of material, and, above all, unequal hardness, wiU always tend to roughness. The proper season for laying the bulk of the fresh materials, is in the autumn and early winter. The precise time at which it can be begun will depend on the climate, weather, subsoil, and the nature of the materials. As soon as the surface of the road softens from the wet, patching the hoUows, wheel-tracks, and channels worn by water, should be commenced, the mud having been previously removed where necessary. The greater part of the new materials should be put on before the end of the year, so that they may be at least partially worked in before winter, when they are most required in the road, and before severe frosts come. Unconsolidated materials are more annoying to the traf&c in frosty weather, and there is waste by the stones being crushed and scattered instead of being incor- porated in the road. Stones laid late in the winter seldom con- solidate thoroughly, and those laid in the spring hardly set at all, but work loose in the dry weather, if they are not of a bind- ing nature. If a road from any cause shows weakness in the spring, and requires stoning, everything must be done to aid consolidation, and great attention to the newly laid materials will be required. All stones which do not bind must be raked off aS the season advances and there is no longer any prospect of their working in. < On a road in good condition, of sufl&cient strength, and with ordinary traffic, by patching hollows as they appear, and by a careful attention to the surface, the materials consumed by wear can be replaced without difficulty, and the thickness of the coat- ing can be added to if necessary. With greater traffic the quantity of materials laid and the size of the patches must be increased. After all hollows or slacks have been covered, or when there are no places which appear to require coating, the proper quantity of materials required to keep the road up to its SPREADING EOAD MATERIALS. 103 full strength should still always be laid. This may be in sheets over the whole width of the road, up to, but not including, the water-tables, and in short lengths, with intermediate spaces free from stones. The wear on a good road is often greater than appearances indicate, and if it be not replaced, although the surface may be kept in perfect condition, smooth and hard, and free from hollows, the road will be getting thinner and weaker, and at last wiU fail from having insufi&cient strength. Experience has shown that this is no imaginary danger. In Prance the system of repairing by small patching and minute attention to the surface was strongly advocated by M. Dumas, and under some engineers was carried to an extreme. It was contended that the more perfect the surface of a road was rendered, the less was the resistance and shock to vehicles, and consequently the less tiie wear of the road, and that, therefore, roads with the finest surface were cheaper to maintain. To obtain this perfect surface the dust or mud was removed by con- tinual sweeping, leaving a clean smooth surface, free from wheel tracks, over whiqh the traffic was supposed to work evenly, and wear the road parallel to itself without forming hollows or ruts. The materials required to replace the annual wear were broken fine and applied in small patches. The outline of the spot to be covered was marked out, and in dry weather watered, the surface was picked up, the loosened materials were raked out and divided into coarse, middling, and small. The coarse was put back with new materials so as to cover completely the place to be repaired. The surface was then rammed lightly, and the middling-sized materials were spread over and rammed, and then covered with small stufp and detritus and again rammed. The sides of tracks formed on the new surface by wheels were rammed, and in dry weather the finished patch was watered daily till it set.* The amount of manual labour was of course large, and more especially so when compared with the quantity of materials laid. On the roads of the department of the Sarthe it amounted to seven days' labour per cubic metre, where, before the adoption * ' Annales des Fonts et ChauBsdes," vol. viii. 1844, p. 273. 104 THE MAINTENANCE OF MACADAMISED EOADS. of the system by M. Dumas, it was only one day. On the other hand, a great economy of materials was claimed, and, on the whole, economy of maintenance was supposed to be obtained, as well as far better roads. The excellence of the roads was undoubted, but the economy, if any, was only obtained by not replacing the annual wear, which was greater than the fine surface indicated. The thickness of the roads gradually diminished, and at a certain point they went to pieces suddenly, keeping an admirable surface to the end. The late Sir J. F. Burgoyne, then engaged on road works in Ireland, called attention to M. Dumas' system, in a paper written in 1843, and advocated its adoption. Constant attention, the prevention of the collection of mud or dust, frequent patching in small quantities with finely broken stone on the first appearance of inequalities, the use of a rammer, and artificial watering, were brought into practice to some extent on the Irish roads, without being ca,rried so far as in France, and with good results. Beipairs ly Thick Coats and Boiling. When the traffic is very great, the quantity of materials required to replace the wear is so large that, if it is put on in patches and partial coatings, the road is always covered with newly laid stones. The plan of laying down a considerable thick- ness at once and consolidating it by rolling can then be followed with advantage. This mode of applying fresh materials has been practised in France since 1840, and since the introduction of the steam road roller it has been a good deal followed in towns in England. Instead of attempting to restore the wear annually, only such repairs are done as are sufficient to keep a good surface on the road, which is allowed to wear as thin as it can be with safety, having regard to its power to carry the traffic, and it is then coated with a thickness of materials sufficient to stand the wear of several years. The consolidation of this thick covering by rolling is of course an essential without which there would be nothing but a return to the old practice of road mending. The advantages to the public of being spared the wear and REPAIRS BY THICK COATS AND ROLLING. 105 tear of vehicles, the excessive draught and labour, and perhaps injury to horses, resulting from the consolidation of large quantities of fresh materials by the ordinary trafiBc, and of having at once a road with a hard and smooth surface, are obvious. In many cases the question whether there is economy in the actual repairs will be a secondary matter compared with the indirect gain to the public both in money and in comfort. The process of rolling has been already described in Chapter II. To make a coating of new materials unite with the old surface, the latter may be picked or stocked up before the fresh materials are laid, but it is not always necessary. The driving wheels of steam road rollers are provided with holes into which steel points may be fixed for the purpose of loosening the sur- face, and saving a good deal of the labour and cost of picking up by band. Binding material must be used, and. artificial watering, both of the old surface and of the new-laid stones, may be required. With the aid of the latter, fresh coatings of stone can be laid as well in the summer as in the wet season, and by some surveyors a better result is believed to be obtained. A less thickness than 4 inches of materials should not be laid down; the coating does not bind so readily, and the cost of rolling is not much greater with 4 inches than with a less thick- ness. It has been already stated that it is unnecessary to break materials which are to be laid with a roller to so small a size as would otherwise be required for patching. The greater amount of wear which always takes place ia the middle of a road must be allowed for by making the cross section rounder than neces- sary at first, that it may not be too flat before the time comes for another coating. A greater length of road than can be completed in one day should not be undertaken at once. The fresh materials may be spread one day, and the rolling may be begun and finished on the following day. On a wide road, one-haK the width of a roadway may be coated and roUed and delivered over to the traffic before the second half is commenced. The inconvenience and loss of time experienced in turning a roller almost dis- appears when a steam roller is used, and short lengths, such as 106 THE MAINTENANCE OF MACADAMISED ROADS. 30 or 40 yards, may be rolled at one time, and the roller may be used from side to side of the road. The area which can be rolled in a day will depend on the thickness of the covering, and on the nature of the material. A horse roller will complete a length of 300 yards on a wide road, and more on a narrower road, with a good binding material, and if the work can proceed without interruption, that is, at the rate of about 1600 square yards per day. The hindrances of street traffic may however reduce this to less than one-half. With a steam roller, Messrs. Mowlem, Freeman, and Burt state that they can roll 1000 square yards a day of the material used in the London streets. Other road surveyors and contractors give from 600 to 2500 square yards as a day's work. The steam rollers in general use are 10 tons in weight, rolling a, width of 6 feet, or 15 tons, rolling a width of 7 feet. Heavier rollers, weighing 20 tons or 25 tons, are sometimes used, but the damage they do to pipes, drains, sewers, &c., is not compensated for by any increased utility. Steam road rollers now work constantly in London and in many other large towns ; and with ordinary precautions, such as blocking up entirely a short length of road, or diverting the traffic to one side while the roller is at work, or giviug warning by a flag-man or other notice, little inconvenience arises from horses being frightened. Economy is claimed for this method of repairs, both on the score of a large saving inroad materials and in the cost of laying them down, and also because less after-labour is required for attending to the surface and removing mud and dust. The result of observations made by M. Graeff in 1850,* on two of the national roads of the department of the Bas-Ehin, one of which had a traffic of 640 collars and the other of 280 collars per day, gave the following particulars of the average cost of the employment of a cube yard of materials spread in a coat about 4 inches thick, and roUed by horse power : — * ' Annales des Fonts et Chauss^es,' vol. ii, 1851. EEPAIES BY THICK COATS AND EOLLING. 107 Delivery and spreading materials Do. do, binding Watering Rolling Purchase of binding material Accessory expenses, maintenance and trans- 1 port of roller / Road 4. 13-8 Road 61. Pence per cube yard. Pence per cube yard. 4-4 3-3 0-8 0-7 1-1 1-0 4-5 3-4 2-9 1-4 0-1 0-1 10-0 This is Id. to l^d. per square yard for a coating 4 inches thick. Wages were 1 • 35 franc per day, and the above prices must be more than doubled to correspond with English prices of the present day. The economy effected by this mode of maintenance was considered to be 20 per cent., not so much on the materials as on the labour, and in M. Graeff s opinion there was no economy at all when a 4-inch coat was required less often than once in seven years, or when the wear was less than J inch per year. In a subsequent memoir,* M. Graeff claims on roads of great trafl&c in the department of the Loire a saving of 30 to 40 per cent, on the quajitity of materials, and another of 10 per cent, on the labour. Experienced surveyors in England estimate that there is a saving of one-quarter or one-third of the quantity of road materials, which, when the traffic is great and the wear rapid, is a considerable set-off against the expense of purchasing and working a Mler. The cost of steam .roUiug, when there is constant work for the machiae, is far less than that of horse rolling, but the actual cost varies very much with the circumstances under which the work has to be done. The result of a comparative trial made in Paris between a horse roUer, weighing 6J tons, and a steam roller, weighing 13 tons, was that, valuing the cost of the horse roller at 5s. per hour, and that of the steam * ' Annales des Fonts et Chauss^es,' vol.'ix. p. 288, 1865. 108 THE MAINTENANCE OF MACADAMISED BOADS. roller at 7s. 6d. per hour, the cost of rolling per square yard was Id. with a horse roller and ^d. with the steam roller. Messrs. Aveling and Porter give the cost of continuously working a steam roUer and rolling from 1000 to 2000 square yards in a day at from 22s. to 25s.. a day, including wages of driver, coal and oil, and wear and tear of the machine, which is at the rate of a penny for from 3 to 8 superficial yards. In addition to the driver, two other men, or a man and a boy, are often neces- sary in towns ; and the cost of watering and of spreading and sweeping the binding material must be taken into account. When the working of the roller is not continuous, the interest and depreciation on the first cost of the machine is, of course, a heavier charge on the work performed. The engines are, how- ever powerful enough to drive stone-breaking machines, and may be provided with arrangements for the purpose, and also with extra wheels for employment as traction engines to remove materials to the roads. By thus utilising them for other pur- poses when not wanted for rolling, the purchase-money may be not left entirely idle. It appears from a table prepared by Mr. Lovegrove, which shows in detail the costs of repairs to roads with a steam roller in the Hackney district,* that the cost of laying coatings of granite from 2 to 3 inches thick, including wages, roller, water- ing, sharpening tools, and hoggin, was from about 2^d. to 5d. per square yard. The average cost of laying the 56,145 square yards in the twenty-one different streets included in the table is for the different items as follows : — Pence. Boadmen and watchmen 1*22 Hire of roller 1'50 Water-carts and water -21 Sharpening picks * 20 Surplus hoggin, &o '51 Total .. .. 3-74 or nearly 3|(Z. per square yard. The solidity and smoothness of a road thickly coated and con- solidated with a heavy roller dimiaishes the wear from the traf&c, * Proc. Inst. C.E. vol. Iviii. p. 63. REPAIRS BY THICK COATS AND ROLLING. 109 and consequently lessens the cost of sweeping, scraping, and removing dust and mud. It is a mistake, however, to leave a road so coated entirely to itself until it is so much worn as to require another thick coat of materials. Continual patching in small pieces should he practised, and this is as much or more required soon after the thick coat has been laid and roUed as later. The ordinary traffic searches out the weak places, which, from containing originally too much binding material, or from having escaped the weight of the roller, are less thoroughly con- solidated, and a road on which a thick coat of stones has been recently laid with the aid of a steam roller often presents a more uneven surface than a road maintained by coatings one stone in thickness worked in by the traffic. Unless the traffic and the wear are very considerable, say at the rate of ^ inch of road surface in a year, there is no economy in adopting this method of road repair, whatever may be the increased comfort to the public, and the lessened draught and wear and tear of vehicles resulting from it. On a thin weak road, the effect of the weight of the roller is destructive. A 15-ton roller, supposing it to bear equally over its whole width, may have no greater pressure on the surface of the road per inch of width than a cart wheel with three-quarters of a ton on it, and yet the load per square inch on the subsoil may be greater. In fact, however, the weight never is equally distributed, and the pressure is excessive at some points, while other portions escape. This is shown by the way in which the ordinary traffic of a road wears into hollows the smooth even sur- face left by a heavy roller. The use of a roller to consolidate a coating one stone in thickness is not advisable on economical grounds, though it may sometimes be desirable for the comfort of the public. Unless the material be very hard, a good deal is crushed by the roller, even if the old surface has been first picked or stocked up. With the latter process, little or no binding material is required besides that derived from the picked-up surface. 110 THE MAINTENANCE OF MACADAMISED EOADS. CHAPTEE IX. SWEEPING AND SCKAPING. DRAINAGE. WATEEING. EEPAIES BEYOND OEDINAEY MAINTENANCE. Sweeping and Scraping. In a good system of road maintenance the removal of the detritius resulting from the wear of materials holds an im- portant place. It may be effected either as dust or as mud. In this country the removal of dust is 'only practised to a limited extent, and in towns ; but in the drier cHmate of France it is considered to be attended with advantage on the roads in the open country, and dust is removed in the summer instead of mud in the winter, so that labour throughout the year is rendered more equal. When the materials of the road are silicious, and consequently disposed to lose coherence in dry weather, the removal of dust is liable to be injurious, by disturbiug the surface, and exposing the loose materials to the wear of the traf&c without the covering of dust which holds them in place and protects them. There is little danger of this on a calcareous road, which remains solid and united in the driest weather. Dust may be removed by scraping, but sweeping is the more usual process. In France a long-handled flexible besom is used, with which a man placed in the middle can sweep from side to side of an ordiaary road, and thus get over two or three miles per day of easy sweeping. Brooms fixed on a horizontal bar, and mounted on a wheel and handles like those of a wheel- barrow, and worked from side to side of the road, are also some- times employed. In England a bass broom is generally used both for dust and mud, with which a man can sweep on an average about 2500 square yards per day. A good deal depends SWEEPING AND SCEAPING. Ill on the nature and condition of the mud. It is stated * that in the streets of Paris a man with a broom will sweep, without putting the mud up into heaps, 700 square yards per hour of macadamised road surface dry and slightly watered, 470 square yards when covered with liquid mud, and 350 square yards when the mud is sticky. Sweeping machines are used in towns to remove both dust and mud. In one machine a revolving brush mounted obliquely sweeps a track about 6 feet wide, and leaves the dust or mud in a line along one side of it, to be afterwards gathered up. Whitworth's machine consists of a series of brooms, usually about 2 feet 6 inches wide, attached to an endless chain running over pulleys suspended in a frame behind a mud cart, the wheels of which give a rotary motion to the pulleys carrying the endless chain and the brooms attached to them. As the cart moves on the brooms are made to bear on the ground with a pressure that can be adjusted according to circumstances, and the mud or dust is swept from the surface up, an incline into the cart. A machine with one man and a horse is saidf to sweep 3 to 4^ acres of street surface per day, removing from 1 to 3 loads per acre, at a cost of from 10s. to 15s. a day for working. A good deal depends on the distance to which the stuff has to be carried, but allowing one-third of the day to be lost in going to and from the places of deposit, a day's work will be 14,000 to 20,000 square yards of sweeping. A scraping machine drawn by a horse is also in use. The scrapers are mounted on a frame oblique to the direction in which the machine is drawn, which is along the road, and the mud is delivered at the hinder end of the oblique line of scrapers. A breadth of about 6 feet is scraped by the passage of this machine, which is, however, not so well able to . follow the irregularities of the surface as the smaller hand machine. These larger machines are little fitted for use on roads in the open country. They are costly, and therefore would, under any circumstances, be few in number, and they require the use of horses, whereas hand scrapers and hand scraping machines * Homberg, ' Annales des Fonts et Chauss^es,' vol. x. 1865, p. 263. t Proc. Inst. Civil Engineers, vol. vi. p. 431. 112 THE MAINTENANCE OF MACADAMISED EOADS. can be kept in readiness at many points, and can be used at once by the roadman when the weather is suitable. The ordinary hand scrapers are generally of steel, about 18 inches wide and 6 inches deep, with the ends bent backward to hold the mud. They are useful at times, when a machine scraper is not at hand, or when it will not act well, as when the road is littered with fallen leaves. Hand scraping is also considered to be more favourable to the road, and it certainly is so when the surface is tender or uneven. Hand scraping machines have many advantages, the quick- ness with which they do their work being one of the chief. They consist of 10 or 12 scrapers 3J or 4 inches broad, hinged to a horizontal bar, each pressed down by a separate spring to enable them to follow the inequalities of the road, and mounted in a frame on a pair of wheels, on which the machine can be pushed backwards with the blades of the scrapers clear of the road, and pulled forwards with the scrapers in action. They are worked from side to side of the road, the most convenient- sized machine scraping a width of about 4 feet at each passage. With such a machine a mile of road may be scraped in a day, two men being employed, one in using the machine, and the other making up the dirt into heaps, or depositing it on the sides. With a hand scraper not a quarter of this work could be accomplished. The best machines are those made of wood with steel-shod scrapers. They are liable to rot from the wet if they are not kept well painted, but they are less liable to damage, and are more easily repaired than those of iron, and they are also cheaper. A machine 4 feet wide costs between 21. and 31., and wiU last 15 years or longer if taken care of. It is sometimes urged against scraping machines that they loosen the surface, drag stones from their places, and remove with the dirt materials useful in the road. This is to some extent true, especially if the surface is bad, or when scraping is done when the road is sticky or tender, and if the- question were whether sweeping or scraping was the best mode of removing mud, it would be entitled to due consideration, but when it is whether mud should be removed by scraping or not at all, the slight injury that the scraper may do when used at improper SCRAPING. 113 times is not worth taking into account. The machine naturally tends to plane down inequalities, and thus gives an even smooth surface, which throws off th? water, and dries quickly after rain, so that the removal of mud not only reduces the proportion of it in the road, but hardens the surface by promoting evaporation, and renders it far better able to stand the wear from traffic and the weather. There is great advantage in scraping being done promptly, when the weather is favourable for the operation. This is generally after moderate rain, when the mud is soft without being too liquid. When it is stiff, the surface of the road is injured by the scraper, stones are loosened in their places, and useful materials are removed with the mud. If a favourable opportunity for scraping be allowed to pass by, the mud may remain on the road for a long time, preventing evaporation, and keeping it moist and soft, and, if frost comes on, causing far more damage in the thaw than would happen on a well-scraped road. Scraping off a thin covering of mud takes almost as much lime, and is, consequently, almost as costly as scraping a thicker coat, and this must be taken into account when, as usually is the case, economy has to be considered. About i inch of mud is generally the thickness which it is best to scrape. The dirt should not be scraped into the side channels, but should be at first drawn into long regular heaps, with openings' at frequent intervals to allow the surface of the road to drain freely into the side channels. When sufficiently dry, the scrapings may be laid on the waste at the sides, or made up into heaps and carted away. It is a good plan to make it one of the conditions of the contract for the supply of road materials that the contractor shall take away the road dirt on receiving notice to do so from the surveyor or road labourer. The neigh- bouring farmers are sometimes ready to take the scrapings for use on their land, but they generally do it at their own time, and if the heans are left on the road they get cut to pieces by the wheels, and washed into the side channels and outlets, and require clearing up a second time before they can be taken away. Under such circumstances it is better to go to the I 114 THE MAINTENANCE OF MACADAMISED EOADS. expense of cartage than to leave the dirt on the road. It is one of the advantages of having room outside the sod bordering that the scrapings can be deposited there, out of the way of all interference with the proper drainage of the road surface until they can be removed altogether. The amount of scraping which roads require is very different, according to the material used and the traffic on them ; and with the same material and traf&c it varies a good deal with the situation. A hill requires little or no scraping com- pared with the flat ground at the bottom, and all damp and shady places need much more scraping than those that lie exposed. It follows from what has been already said (p. 57) relating to road detritus, that if we suppose the exact amount of detritus resulting from wear on a road to be removed, and to be replaced by new materials, the quantity removed would be less in bulk than the materials applied, whether the detritus were removed as dust or as stiff mud, but that in the latter case the weight would be increased by the addition of about one third the bulk of water, or by about one-fifth ; that is to say, on a road on which wear is exactly replaced, 1^ the weight of materials worn out would be removed as a stiff mud. Actually however this is modified by several causes. Some detritus is washed away, and on the other hand the quantity is increased by horse droppings, rubbish from houses, &c., and also by dirt from fields or other roads, and the proportion of water is often greater. It is not, perhaps, far wrong generally to put the weight removed as mud from a well-maintained road at IJ times the weight of materials worn out. When, from neglect in removing it, the road contains a large proportion of detritus, great quantities of mud can be scraped off in wet seasons, so as sometimes to lead to the belief that it comes from the subsoil. A thorough removal of the superfluous mud is what a road which has been neglected or improperly maintained often requires most. The coating may contain plenty of stone, but mixed with perhaps more than twice as much mud as it ought to have, and until this is reduced to a proper proportion by continued scraping, it is impossible to get a good road. In such a case laying more SCRAPING. 115 materials only hinders scraping, which cannot he done over unconsolidated stones. With the autumn rains the results of wear through the summer months appear as mud in considerable quantities on the surface of the road. The early autumn is, therefore, the time when scraping is most necessary, and it should be done whenever the weather is favourable for it, so that it may not be behindhand when the time for laying fresh materials comes on. The advantages of keeping the surface free from mud, and the body of the road hard, with no more than a proper proportion of detritus in it, are so great that there is generally no danger of scraping too much. It is, however, possible by over- scraping to increase the consumption of materials by removing stone of a size which would be still useful in the road, and also in some cases by increasing the wear of that remaining., On a good road in which the mud does not work up from the subsoil, and in which the amount of detritus is kept down by scraping to the proportion which is essential, the quantity of mud which appears on the surface and is scraped off is determined by the wear, and it should be replaced by an equivalent quantity of fresh materials. When, however, from want of funds or other cause, the new materials are insufficient to replace the wear, the road may get weaker in two ways. If the removal of mud is carried on to the full extent, the thick- ness of the coat will be reduced, while the proportion of mud and small stuff in it will remain the same. If the mud be only partially removed, the road coating will deteriorate by retaining a larger proportion of detritus. By which of these courses the strength of the road will be best maintained, whether by allowing the coat to get thinner with a smaller proportion of detritus, or by preserving thickness with a larger proportion in it, will depend almost entirely on the special conditions of the road. it must be remembered that scraping must always remove materials more or less useful in the road, as well as mud. It has already been stated that scrapings from very good lime- stone roads were found to contain one-third of small stone that" I 2 116 THE MAINTENANCE OF MACADAMISED EOADS. could not be washed through a cloth having twenty threads to an inch, and ranging to pieces ^ inch or more in diameter, when the roads were scraped under favourable conditions ; and it appeared that, of the whole coating of the same roads, about one-third consisted of such stuff as would be removed by- scraping. These facts suggest caution in scraping when the materials used by wear are not replaced. On the other hand, a road containing a large quantity of detritus is more affected by wet and frost, and wears more rapidly, perhaps by as much as one-third more, than a road with a full proportion of stone in it, so that, when a road is naturally wet, or the materials are soon acted on by the weather, there is danger in allowing the proportion of detritus to increase too much. A road of ample thickness may safely be scraped thinner, and it will generally be the best course where the subsoil is of a hard, dry, or rocky character, or over a paved foundation. * Drainage. Attention to the drainage both of the surface and of the subsoil of a road is a matter of great importance. The wear of materials may be increased two or three fold on a badly drained road, which, after all, will never be good ; indeed, other care is almost entirely thrown away on a road of which the drainage is neglected. The good drainage of the surface depends on the preserva- tion of the cross section with sufficient and regular fall towards the sides, so that water may not hang about in puddles. It has already been pointed out (p. 12) that smoothness and fairness of surface are more important than either extreme convexity or any particular form of cross section. The latter may often be varied with advantage within certain limits to suit the situation ; and it always will be so, more or less, as maintenance goes on, but a fair surface to throw off the water is' essential. From the side channels, or water-tables, the water should be passed at once by outlets, or gullies, to the side ditches or other drains, and the course that it will take from any part of the road should be well known to the road- DKAINAGE. 117 man. On a level, the fall in the water-table is but slight, and the wash from the surface of the best kept road will lodge in it, and afford a soil for the growth of grass and weeds, and hinder the flow of water. On steep gradients the outlets from the water-tables are more liable to stoppage, and when this happens the water runs down the side channel and scours it, and perhaps breaks out and damages the surface of the road. Slight but frequent attention is therefore required to maintain the flow of water from every part of the road, by removing obstructions both in the water-tables and outlets. The scouring of the surface on hills, which is often the cause of great damage, must be guarded against beforehand. Every beginning of a water-course must be checked, and all points where water usually breaks out from the side channels, or where outlets or drains get stopped, should be watched and have attention at once in heavy rain. Outlets and drains should always be cleared after a storm, as, if another storm finds them unopened, great damage often results from the neglect. A thorough clearing out of both water-tables and outlets should take place in the autumn, as soon as the dry weather has passed. If all silt and road dirt is then removed down to the hard bottom, leaving nothing to give a hold to grass or weeds, this will generally be often enough for a general clearing up. The sod bordering should, at the same time, be trimmed with a spade by the aid of a line to fair curves. This, though very much aiding the flow of water, as well as giving a finish to the road, is not so essential as the opening of the outlets and the cleaning up of the side channels; and when time .presses, it is sometimes necessary to open the outlets, and to trim the sod bordering and clear the side channels near them first before wet weather sets in, leaving the general cleaning up until afterwards. This, of course, involves some waste of time in the end, from going over the ground twice. Undue deepening of the water-tables in cleaning them, and thus converting them into steep-sided gutters, should be guarded against. There should always be a fair and gradual curved slope from the general surface of the road to the sod bordering. 118 THE MAINTENANCE OF MACADAMISED KOADS. Cleaning up the sides, trimming the sod bordering, and opening the outlets, is work which may be done by the piece, though it is doubtful whether there is any advantage in it. The work may be finished more quickly, from the men working longer hours, but there is the chance of its not being so thoroughly done, and if not, it will soon require doing over again. Under ordinary circumstances, a man can thoroughly clean up the water-table, trim the edges of the sod bordering, and open the outlets, of 6 to 10 chains of road per day. When there is little traf&c, the work of cleaning the sides is heavier, and as little as 4^ chains of road is a fair day's work ; and in dry situations, or where a considerable traffic leaves less cleaning up to do, a man may get over 12 or 14 chains of road in a day. Useful materials taken out of the water-tables can generally be disposed of on the road, or they may be laid aside for use with the fresh materials, and soil and dirt may be laid on the waste, or gathered in heaps for removal by farmers and others. Scrapings and dirt laid on the waste should be deposited quite away from the edge of the sod bordering, so that the latter may never be more than a few inches high. A steep slope of earth or scrapings, 9 inches or 1 foot high, is always mouldering away into the water-tables, and causing extra labour for clearing them. All side-ditches, back-ditches, and drains, require to be cleared out periodically, and the best time to do it is in the spring and summer, the drier ones while the soU is moist and easy to move, and the wetter ones afterwards in the dry weather. Some ditches require to be opened every year, others far less frequently ; but they should always be kept clear. There are few things that show a neglected or badly managed road more than water standing in the side ditches or drains, and soaking up under the road. Whenever it is possible, the water level should be kept 1 foot at least, or even 2 or 3 feet, below the road, and to ensure this, the cost of additional drains or culverts would be often well incurred. Covered drains require examination from time to time, and all blind drains, composed of loose stones, have to be renewed DRAINAGE. 119 as they become choked up. Drains along the side of a road benched into a hill, to cut off the land water, should always be kept in good working order, and improved if the road seems to need it. A surveyor has, under the General Highway Act, consider- able powers with respect to the drainage of his roads. He has power to "make, scour, cleanse, and keep open, all ditches, gutters, drains, or water-courses, and also to make and lay such trunks, tunnels, plats, or bridges, as he shall deem necessary, in and through any lands, or grounds, adjoining or lying near to any highway, upon paying the owner or occupier of such grounds, , provided they are not waste or common, for the damages he may sustain thereby, to be settled and paid in such manner as the damages for getting materials in inclosed lands or grounds are to be settled and paid," * and the owner or occupier may not alter, obstruct, or interfere with such ditches, &c., without the consent of the surveyor. Whatever duty exists on the part of owners of lands adjoining highways to cleanse and scour ditches appears to extend only to the prevention of nuisance, or obstruction to passengers, and not to the drainage of the road. Farmers are often willing to clear out the side-ditches for the sake of the soil obtained from them, and are apt to deepen them unduly where stuff fit for their purpose can be got, and neglect them in other places. It is better, therefore, that the work, if not done by the road labourers, should be done under their direction, so that the ditches may be regularly opened throughout, and when they require it. On hills, side-ditches sometimes scour deeper and deeper tni they become dangerous. This can be prevented by small weirs of fascines and stones, made by the roadmen at a nominal cost. The effects of hedges and trees, especially on the south side, in keeping roads wet, and the injury thus caused, particularly on a clayey or imperfectly drained subsoil, have been already mentioned. The General Highway Act t provides that, if the surveyor shall think that a road is prejudiced by hedges or * 5 & 6 Will. IV. cap. 50, sect. 67. t Ibid, sect. 63. 120 THE MAINTENANCE OF MACADAMISED ROADS. trees, he may summon the owner to appear before the justices at a special sessions for the highways, and if they shall order the hedges and trees to be pruned and lopped, the owner shall do so within ten days, under a penalty, and the surveyor, in case of default, may do the same at the owner's expense. The term owner is made to include the occupier by the interpretation clause. No person is compelled to cut or prune hedges at any other time than between the last day of September and the last day of March, and trees planted for ornament or shelter are excepted. These provisions should be enforced, but with discretion and tact on the part of the surveyor, as there are few parts of his duties more liable to bring him into collision with owners and occupiers of land. Waiering. For the sake of the road itself, a road, except one of a silicious nature, seldom requires watering in this country. In very dry weather judicious watering binds the surface of a gravel or flint road, and lessens wear, but on other materials, even when done sparingly, it softens the road and increases the wear. In and near towns watering is necessarily practised for the comfort of the inhabitants, but it should be done in moderation, sufficiently to lay the dust without softening the road. The amount of watering required may generally be considerably reduced by preventing the accumulation of dust, by sweeping either com- bined with slight watering, or early in the morning while the dust is laid by the dew. By far the greater part of the nuisance from dust may be avoided by removing the mud. It is too often the practice to leave the mud on the road, and, when it dries to dust, to reconvert it into mud by copious watering. "Watering is sometimes useful when mud is sticky, to prevent the tearing up of the surface by the wheels, and it may some- times be advantageously combined with scraping or sweeping. The mud, when rendered soft and almost liquid by watering, is more easily removed, and grit of a useful size is left behind on the road. WATERING. 121 Mr. Santo Crimp states * that a fall of ' 04 inch of rain will lay the dust on a well-kept macadamised road, and also effect a very slight washing, and that that amount, or about one-fifth of a gallon per square yard is the usual quantity of water which he spread at one watering at Wimbledon, where the roads were watered on 132 days in a year. In the metropolis it is usual to allow for 130 days watering, and the records of rainfall at various places show that from 120 to 130 is generally the number of days on which less than • 04 inch of rain is registered in the six summer months in this country, the days on which no rain is registered being about 100. The total annual rainfall has some influence, but the number of days on which less than • 04 inch is registered appears to vary much less than the total rainfall. Ordinary water-carts contain between 220 and 300 gallons, and deliver about half a gallon to the square yard of road, spreading it over a width of 12 to 16 feet. When watering is performed by contract, much more than this quantity is often delivered. Deluging the road prevents the necessity of frequent watering, and the sooner the cart is emptied the better for the conbractor. The holes of the distributor have been found en- larged for a quicker discharge of water, and a thick cast-iron distributor has been used to prevent it. According to a report of the town surveyor of Derby,j a superficial area of 23,849 yards can be watered by carts twice a day, being for a width of 4 yards, 5962 yards lineal, or for a double width, 2981 yards lineal, at a cost of — s. d. Horee, cart, and man . . . . 8 Maintenance of carts, hamess, shoeing, &c 1 5 Total 9 5 per day. This is exclusive of the cost of the water. In Paris the total cost of watering with rather more than half a gallon to a square yard of macadamised road is said to be about \d. per square yard. * Proo. Municipal and Sanitary Engineers, vol. xii. p. 235. t A Report, &c., by E. B. EUice-Clark, 1876, p. 25. 122 THE MAINTENANCE OF MACADAMISED EOADS. The old-fashioned water-carts on two wheels are now generally superseded by Bayley's patent hydrostatic vans, consisting of a wrought iron tank holding 450 gallons, mounted on springs and carried on four wheels, and drawn by one horse. They are no wider than an ordinary water-cart, but in consequence of improvements in the branch and distributing pipes they water a track 20 to 23 feet wide much more uniformly than a cart, and the outflow of water can be regulated by a valve. A great saving is effected by their use, as, in consequence of their holding a much larger quantity of water, less time is taken up in going backwards and forwards to refill. It is stated * that experiment has shown that a van will water an area of 161,000 square yards per day. The saving in London parishes by the use of the vans has been estimated at from 20 to 50 per cent. The first cost of a van is 60Z., compared with 251. for an ordinary water-cart. In a trial in Eegent Street a van holding 450 gallons of water spread it 23 feet wide over 6746 square yards, being at the rate of a gallon to 15 square yards ; while a cart holding between 250 and 300 gallons of water spread it 16 feet wide over 2560 square yards, being at the rate of a gallon to 10 square yards. In each case the quantity of water delivered per square yard of surface was far less than is usual. In Mr. Santo Crimp's experience a van holding 450 gallons waters a length of 480 yards of an average width of 5 yards, or 2400 square yards at the rate of "192 gallon per square yard, and Mr. EUice-Clark gives the length as 462 yards of an average breadth of 17 feet 9 inches, or 2733 square yards at the rate of • 165 gallon per square yard. ^?h6 -cost i« -stated iry Mr. Crimp to be 1 • 92d. per 1000 square yards for water at lOd. per 1000 gallons, and 1 ■ 37d. per 1000 square yards for watering, together 3'29d. per 1000 square yards. WUlacy's watering machine is fitted with horizontal rotating spreaders actuated by the wheels. As the cart proceeds the spreaders revolve and throw the water to a width, it is said, of 33 feet. The machine is well spoken of. Street watering is sometimes effected by a movable hose and * Report by the Surveyor of the Parish of St. Marylebone; EEPAIES BEYOND ORDINAKY MAINTENANCE. 123 jet, or by light iron pipes jointed together and carried on small trucks, in connection with the hydrants, and the system of Messrs. Brown and Co., by which the water issues in small jets from perforated pipes laid along the kerbs of the footway, has been tried in the City and elsewhere, but has not been much used. In sea-side towns sea-water is used, the effect of which is to keep the surface moist, so that less than half the quantity of water is required to keep the dust effectually laid. A skin also forms on the surface which tends to bind sUicious roads together. The only objection to the use of sea-water appears to be the injury that may be done to ladies' dresses, or coloured fabrics exposed for sale by excessive or careless watering. A patent has been taken out by Mr. W. J. Cooper for mixing chlorides of calcium and sodium with the water for street watering, iu the proportion of J lb. or 1 lb. to a gallon of water. It is said that the surface of the road is not only kept moist by the deliquescent salts, but that they have an effect of concreting and hardening the surface of a mac- adamised road, so that little dust arises from it when dry. It has been found in Paris that the use of these chlorides produces a very good effect for the first twenty-four hours, after which slight additional waterings are required, and the process must be recommenced after the fourth day. Instead of moistening and refreshing the air as common watering does, the employ- ment of deliquescent salts robs the air of the humidity which it contains. Bepairs heyond Ordinary Maintenance. On a bad road the ordinary processes of maintenance have to be applied to something beyond keeping up the condition of a road already in a "good state. The first thing to do is to examine the road and find out the cause of its badness, and ascertain, by pitting or sounding, its composition and thickness. If the coating is thin and so mixed up with the subsoO. as to have lost all consistence, it may be necessary to form a new coating on it of sufficient thickness to stand without being cut through and mixed up with the old surface; and it may be 124 THE MAINTENANCE OF MACADAMISED ROADS'. necessary to lay on a thickness of more than one stone at once. In many cases continual scraping combined with small patches of new materials to give form to the road is enough, there being suflBicient thickness and plenty of stone, but, from neglect, too much mud. It may take several years to form a solid compact coating, and as the scraping reduces the thickness, large stones may have to be taken up, but the rest of the surface should not be disturbed if it can be avoided. The treatment which a bad, road may require may range from ordinary maintenance to the reforming described in Chapter II. One thing, the drainage, will always be an important matter to attend to in any attempt to improve the condition of a road. Besides the ordinary wear from the traffic and weather, there are damages which arise from unusual or accidental causes, which must be dealt with specially according to circumstances. When a road has been broken up by frost and thaw, the best remedy is to consolidate it again by rolling. If this is impossible, it should be left to the traffic to consolidate it, with raking and attention on the part of the roadman. Spreading fresh stones on a surface already disintegrated only adds to the quantity of loose materials, and is rarely right, though patches may be useful here and there. Holes are sometimes broken in the crust of a thin, worn road, under unfavourable circumstances of traffic and weather, and the subsoil works up and mixes with the road-coating, forming what is sometimes locally called a " mustard-pot," into which a horse's foot wUl plunge to a considerable depth. The cause is always water in the subsoil, sometimes from springs, and though drainage is the general remedy, coupled, on a bad bottom, with an increase in the thickness of the road-coating, the mode of promptly repairing these dangerous holes must depend upon the nature of the subsoil. If it be muddy or boggy, putting down broken stones is useless, as it soon works into the soft bottom. The whole, or a considerable thickness of the latter, must be dug out, and large stones, flat if possible, must be laid as a foundation for 4 or 5 inches of road materials. On a sandy bottom broken stone alone may often succeed. In any case the water must be tapped and led away by a drain. EEPAIRS BEYOND OEDINAEY MAINTENANCE. 125 The passage of exceptionally heavy loads, such as a traction engine and its trucks, sometimes breaks through the crust of a weak road, and makes a ' succession of holes of this sort, at points where the coating is thin or the subsoil soft. Eepeated passages may form a pair of continuous tracks, 2 or 3 feet wide, in which the road coating is entirely destroyed and mixed up with the subsoil. It is useless to attempt repairs by adding more materials on the surface, as they are swallowed up and wasted. Everything, down to a firm bottom, m,ust be dug out and removed, and the space must be filled in with stone, which may be of large size at the bottom. The drainage should always be looked to, and improved if it requires it. The stuff dug out of the road may be raked over when dry, to separate the useful metalling from the clay. Such repairs have some- times certainly cost between 100^. and 2001. per mile, and it has been stated that in some cases the cost has been at the rate of as much as 500Z. per mile. The expenses incurred in repairing a road damaged by excessive weight or extraordinary traffic can be recovered by the road authority. By section 23 of the Highways and Locomotives (Amendment) Act, 1878,* " where by a certificate of their surveyor it appears to the authority which is liable or has undertaken to repair any highway, whether a main road or not, that, having regard to the average expense of repairing highways in the neighbourhood, extraordinary expenses have been incurred by such authority in repairing such highway by reason of the damage caused by excessive weight passing along the same, or extraordinary traffic thereon, such authority may recover in a summary manner from any person by whose order such weight or traffic has been conducted the amount of such expenses as may be proved to the satisfaction of the court having cognisance of the case to have been incurred by such authority by reason of the damage arising from such weight or traffic as aforesaid : provided that any person against whom expenses are or may be recoverable under this section may enter into an agreement with such authority as is mentioned in this section for the payment to them of a composition in * 41 & 24 Vict. cap. 77. 126 THE MAINTENANCE OP MACADAMISED EOADS. respect of sucli weight or traffic, and thereupon the persons so paying the same shall not be subject to any proceedings under this section." The Act thus recognises the principle that those who damage roads by bringing upon them weights which they are not fitted to carry should bear the cost of the repairs, and if this could be enforced in practice, it would be a far better protection to the roads than bylaws regulating the width of the tires of the wheels. Holes or trenches dug to get at or lay gas or water mains, and carelessly filled in, in wet weather sometimes cause trouble- some places in a road. Properly ramming the stuff refilled in the hole or trench, and putting on a sufficient thickness of metalling at first, so that the wheels shall not cut through and mix it with the subsoil, will prevent this, and it is better not to raise the fiUing-in too much at first above the road surface. In descending a hill, heavily loaded waggons, or timber carriages, are apt to keep one wheel in the water-table by way of a drag, often either breaking down the road-coating or bending it into a series of undulations. Fresh materials will not remain in the hollows thus formed so long as the heavy traffic continues, and it is of no use to lay them. Afterwards the sides must be levelled with a pick and coated. Bridges, culverts, and drains, especially where they are exposed to the action of quickly running water, require watching by the roadmen, and examination from time to time by the surveyor. The scouring away of the bed of the stream and the undermining of foundations are the most frequent causes of damage where bridges or culverts have been built without an invert. The lower ends of culverts are particularly liable to be undermined. An invert, or a pitched apron with timber snis, is often required to protect foundations thus exposed, but a good deal may be done to prevent damage by checking the scour by weirs at the lower end, or by other suitable means. Obstructions generally occur at the upper ends of culverts, and they should be removed at once. A stoppage in heavy rain will be the cause of great damage from scouring the surface of the road, and in hilly countries the road itself may be washed NAEKOWING AN OVEE-WIDE EOAD. 127 away. In fine weather slight repairs can be done at a nominal cost which will prevent damage to the extent of many pounds in a storm. Ohstructions from Snow, &c. If any impediment or obstruction shall arise on a highway from accumulation of snow, or from falling down of the banks on the side, or from other cause, the surveyor is required,* from time to time, and within twenty-four hours after notice thereof from a justice of the peace, to cause the impediment or obstruction to be removed. Clearing away snow is on some roads almost an annual expense, and on some exposed places it is sometimes worth while to keep a snow-plough ready for use. This consists of two planks shod with iron and fastened together in a V. which can be drawn by a horse, point first, through the snow, clearing a track wide enough for a vehicle to pass along. A useful size is made of two 9-inch planks about 8 feet long spreading to a width of 8 feet, and joined by a platform which can be loaded with stones. Snow-ploughs can easily be improvised for use on an emergency. They are useless in heavy drifts, which must be cut through by men. Narrowing an Over-wide Road. Considerable economy can often be effected in the cost of maintaining a road by narrowing it to suit the requirements of the trafi&c where it has fallen off. It is sometimes difficult to induce roadmen, and even surveyors, to give up excessive width in a fine broad road from which the greater part of the traffic has been diverted by railways. It is sometimes said that the traffic is the measure of the wear of the road, and that the result is the same whether it be distributed over a wide or a narrow road. But except in crowded thoroughfares, where the vehicles are obliged to use the whole width of the road, this is far from being the case. The traffic has a strong tendency to keep to one track, alid the rest of the road, although it may be * 5 & 6 Will. IV. cap. 50, sect. 26. 128 THE MAINTENANCE OF MACADAMISED EOADS. little worn by the passage of vehicles, is subjected to all the action of the weather, anji requires almost as much labour for scraping, &c., as the part used by the traffic. The grassing over of the sides is a sure indication that the metalled surface is wider than necessary, and affords a means of judging to what extent it can be narrowed. The new width should be regularly defined by a turf border- ing, which will not prevent the passage of wheels over it on an emergency. Block stones may be used to protect the edges of the turf, but they should not project beyond the sod to form dangerous obstructions. Some attention to the new water- table will perhaps be required, and it is often best to leave the former water-table as a back drain, and connect the new one with it at "frequent intervals by outlets through the turf bordering. The result of narrowing the metalled surface is often not only a reduction in cost of maintenance, but an improvement in appearance, as a road too wide is generally irregular and dirty. ( 129 ) CHAPTEE X. MANUAL LABOUR. PROPORTION OF EXPENDITURE ON MATERIALS AND ON LABOUR. Manual Lahowr. The constant attention which a road requires to keep it in good order is hest secured by putting a labourer in charge of a certain length. Eoad maintenance has been said to be an incessant contest of a man aided by a few yards of broken stone, and a few simple tools, against the constant action of the traffic and the weather, and it is certain that in nothing is the maxim, that " a stitch in time saves nine/' more applicable. In 1819 working foremen were placed in charge of lengths of from four to six miles of the Holyhead road between Shrewsbury and Bangor, having under them a sufficient number of labourers to keep the road in proper repair. Telford says :* — " A certain number of labourers ought alwaj'-s to have the care of the surface of the road and never quit it for a single day to do anything else ; they will always have sufficient to do in spreading fresh materials in ruts and hollows, in scraping the road, in cleaning out the side channels and keeping open the water-courses, and generally in maintaining the road in a clean and sound state. A few men constantly so employed will do a great deal towards the preservation of a road, while the greater number of workmen should be as constantly employed in providing materials by contract work." The duties of a constant road labourer could hardly be more succinctly described. The " General Eules for Eepairing Eoads," issued at the same time by the Parliamentary Commissioners, to the turnpike trustees on the Holyhead road between London and Shrews- * Report on Holyhead Road, 1823. K 130 THE MAINTENANCE OF MACADAMISED EOADS. bury, contain no such recommendation ; but, on the contrary, the discontinuance of all labour by day wages as much as possible is insisted upon as essential. This was probably with a view to getting rid of the old paupers then employed on the roads, whose work was no doubt almost useless, and in the end wasteful, but as these rules were published, and looked upon as setting forth the proper principles of road maintenance, the result appears to have been that the employment of men in charge of a certain length of road did not become general, though the constant attention given to the roads under both Telford and McAdam was one important cause of their im- provement. In 1833* labourers called nulemen had been for several years in charge of one mile of road each, on the Windsor and Bagshot roads, under Sir J. McAdam. They had assistant labourers when required, and it was considered that two men, working under a practical and skilful mileman, were equal to three men working independently. Eewards were given every year to deserviug milemen, and a good deal of emulation was produced among them, and it was found that a less quantity of materials was consumed. The Committee of the House of Lords before whom this was given in evidence reported that "the measure of employing permanent milemen, with occa- sional assistant labourers on the roads, has combined such indisputable advantages that we do not hesitate to recommend its more general adoption." This recommendation appears not to have been much attended to, for in 1841 the successful organisation of such a system in this country was claimed as a novelty by Mr. Chaloner,t who appears to have become acquainted with it in France, where " cantonniers " had long been in charge of lengths of road. At present in France each cantonnier has a portion of road called a canton under his charge, and about six cantons compose a brigade under a chief cantonnier who has a shorter length than the others, and is expected to pass over his brigade once a week at least. The men wear a distinctive dress, and they mark their * Sir J. McAdam's evidence, Select Committee on Turnpike Trusts, 1833. + Journal of Royal Agricultural Society, vol. ii. p. 353. MANUAL LABOUR. 131 place of work by setting up a measuring rod surmounted with a mark showing the number of the canton. They keep a sheet on which they enter the work done by themselves and their auxiliaries, and a book wherein notes and orders are entered. A code of rules prescribes the conditions of service, the hours of work, and in some detail the manner in which work is to be done, and discipline is enforced by fines and rewards. A trans- lation of these rules, which are for the most part applicable in this country, is given in Appendix I. ' In 1845, when the system on which the county roads of South Wales were managed was organised by the late Sir H. D. Harness, E.E., constant labourers were put in charge of various lengths over the whole of the roads. The experience of forty- three years on roads of all sorts, from the streets of seaport and manufacturing towns to mountain roads, has fully proved the advantages of the plan. Skilful, practical, and industrious road labourers have been obtained, who take a pride ia their road, and are capable of directing to the best advantage the labourers they have to assist them. The constant labourer has entire charge, under the surveyor, of his portion of road, and is responsible for the work performed by the assistant or casual labourers employed under him. He also sees that the instructions given by the surveyor to con- tractors and others are properly carried out. It should be his constant care to prevent the formation of holes, ruts, or hollows in the surface, and thus prevent or lessen the wear from the traf&c or the weather ; and this forms quite as important a part of his duties as the application of fresh materials for repairs. He should be on his road all day, wet or dry, and no excuse should be allowed for absence. During rain it is particularly necessary that he should be on his road. He can then see where the water-tables need clearing out or lowering, where the outlets to the ditches require opening, or where a culvert or drain is choked ; and a little attention on a wet day will often prevent much damage, and save much after labour and expense. Wet weather is often the most favourable time for scraping, and the unevenness of the surface is then also most apparent, and shows where patches of materials are required. K 2 132 THE MAINTENANCE OF MACADAMISED EOADS. In storms of heavy rain the roadman should go at once to any point likely to suffer from breaking out of water, but, except in cases of emergency, he should go regularly through his beat, giving to each part the time it needs. Much time is wasted in running from one point to another, and the road is unequally attended to. A good roadman soon becomes familiar with the length under his charge, and knows what part will repuire his attention under the various conditions of the weather, and the best way of dealing with it, and he will keep his road ia a superior condition with far less materials and labour than a less experienced man. Without very good reason, a man should not be moved from the road under his charge to a fresh length. When a man by his skill and attention has brought his length to good condition, it is discouraging to him and to other good men to move him, even should it appear to be for the beneiit of another length. Considerable intelligence and aptitude, as well as the super- vision of a surveyor who understands his work, are required to make a good roadman. Some men, however industrious and well-trained, never become good roadmen, and the surveyor should be allowed a good deal of liberty in his selection of proper men, and in determining their wages. It must be fully recognised that the surveyor can be but seldom at hand to give orders, and that much must be left to the initiative of the roadman, who must day by day accommodate his work to the weather, and to get and keep good men proper wages must be paid. The false economy of paying low wages to unskilled men is evident. A shilling a week in wages represents the value of from 5 to 8 cube yards of materials, and it is certain that a good roadman wOl save much more material than that out of the 200 or 300 cubic yards he may use on his length, which would be absolutely wasted by an incompetent man. The division of roads into lengths, each under one man's charge; makes it easy to compare one man's work with another's, and to excite emulation among them. In some of the counties of South Wales a sum of money was distributed annually as premiums among the most deserving constant labourers, and was found to be of value as an encouragement. In other counties it was found to provoke jealousy, and was either MANUAL LABOUR. 133 abandoned or every constant labourer had Ms share, unless there was special reason to the contrary. The general good condition in which the road is kept, economy in use of materials and casual labour, regularity and punctuality, should all be taken into account in allotting the premiums. The constant labourers should be required to keep books in which to enter an account of how they occupy their time, and the time of the casual labourers employed to assist them. The pages may contain columns headed with different descriptions of work, such as scraping, laying stones, raking, cleaning sides, and other work, so that the labourer need enter only the time, in days or parts of a day, under the proper heading, These accounts are very useful as a check of the men's work, and as a means of comparing constant labourers one with another ; but they should not lead the surveyor to slacken his personal attention to the men. The form of a constant labourer's journal is given in Appendix II. The employment of constant labourers by contract or piece- work in cleaning the sides, scraping, and spreading stone, is not advisable. The interest of a constant labourer should be the good of his road, and while a good man will work as well by day-work as if he were on piece-work, another may be tempted for his own interest to get over his piece-work in a superficial manner, leaving it to be more thoroughly done when he is on day-work. Such work as cleaning the side channels or water- tables, and opening outlets, if not thoroughly done, soon requires to be done again, from the growth of grass and weeds in the dirt left behind. Any task work is best done by casual labourers working under the eye of the roadman in charge of the length, but even then spreading stones by the cube yard is very likely to lead to a waste of materials, and entail more after-attention. Working foremen are sometimes employed under a surveyor to superintend the labour on the roads. A foreman should be a skilful workman, able to show to others, tool in hand, how work should be done. He may have a short length under his own charge, but not too much to prevent his passing frequently over the other lengths which he is to superintend. He should keep a journal, and note in it what he does himself, and what he finds the other men doing when he visits them. The drawback to 134 THE MAINTENANCE OF MACADAMISED ROADS. the employment of working foremen is that it lessens the responsibility of the labourers in charge of lengths, of roads, and when they are well-trained and trustworthy men, any other superintendence than that of a good surveyor is seldom required. The tools used by a roadman are, a wheel-barrow, spade, shovel, mattock, pick, rake, scraper, stone hammers, and a reel and line. Near towns brooms are required. It is usual for the labourers to provide their own tools ; but this has been some- times found to lead to the use of inferior tools, and a waste of labour. The men may with advantage be required to keep their tools in repair, having an allowance for the purpose. Blacksmith's bills for repairs of tools cannot be checked by the surveyor, and are often considerable. The machine scrapers are always provided for the men, and there should be a machine in charge of the constant labourer on every length of road. Wheelbarrows are sometimes provided likewise. The tools of the country are usually employed rather than the special tools for road work figured in the " General Eules for Eepairing Eoads" issued in 1819, and copied up to this time in treatises on road-making. It is, in fact, difficult to get men to use tools they are not accustomed to. The pronged shovel for laying stones is never used ; it would leave behind a good deal of useful material when the stone is broken to a small gauge. The road level is not used in road maintenance ; and for forming and testing the cross section of roads, ordinary levelling and " boning," supplemented by the eye of the work- man, are generally found more convenient. The road level resembles in general form the ordinary bricklayer's level, con- sisting of a straight-edge long enough to reach from the middle to the side of a road, having an upright in the centre supported by braces and carrying a plum-bob by which the straight-edge is set level. Gauges attached to the latter can be adjusted to any offset from the lower edge to give the profile of the road. With moderate traffic, such as on main roads in the country, the length which can be most advantageously placed 'under the charge of one man is that on which, when the materials are supplied ready broken, the roadman's time will be fully utilised MANUAL LABOUR. 135 all the year round, and which he can keep in good order with help from casual labourers during two or three months in the autumn and winter. This length will depend on many local circumstances, such as the traf&c, breadth, situation, and materials of the road. Through a town or village the labour is much greater than in the open country, and on a hUly road the care of the water-tables, outlets, and side-ditches, tO'prevent water scouring the surface, may require, perhaps, twice as much attention as the same length of moderately level road. Soft materials, a bad or undrained subsoU, or a situation sheltered by trees, entail much more labour. Whenever possible, the length should be such that the roadman can go over it all daily, and he should do so twice a week at least. On a long length this leads to waste of time, especially if the length be a portion of one road only, and not made up of several pieces of different roads lying near together. The length which may be best allotted to a man may, from these causes, be from two or three miles up to seven or eight, and it wiU always be a matter for the surveyor's judgment whether to give short lengths of road or longer lengths with more assistance from casual labourers when the work requires it. The work which casual labourers have to do i's little more than an ordinary country labourer can perform, but they require the direction of the constant labourer how and when to do it, and they often waste much of their time when not working with the roadman in charge. It is therefore seldom well to have too many casual labourers, and two or at most three are enough to work to advantage under the direction of one constant labourer. On roads on which there is a good deal of work to be done, a constant labourer may require the help of another man throughout the year, as weU as additional men in the autumn ; while on unimportant roads the roadman may break stones during the summer months, or he may be permitted to do work not connected with his road. In such cases, however, he should always be considered to be in charge of his length, and ready to give his attention to it in any emergency, such as a heavy storm. 136 THE MAINTENANCE OF MACADAMISED EOADS. In Trance, where much more labour is given to the roads than is usual in this country, it is found that a cantonnier can employ about 260 cube yards of materials per year, and remove the corresponding detritus* There is sometimes considerable difficulty in keeping down the amount of surface labour to what is absolutely necessary. The roadmen are necessarily a good deal without supervision, and they may waste their time, or neglect their work, if they are not trustworthy. Even with a good roadman the cost of labour may be unduly increased. The pride of a man in his road's appearance sometimes leads him to devote time to work which is superfluous or ornamental, and he may in good faith believe that he has too long a length of road, when in reality he could undertake, more, without the road beiag in any essential the worse. The great difficulty in arranging labour arises from the inequality of the work at different seasons of the year. In the summer months the surface of the road requires little beyond the general attention of the man ' in charge, who may employ most of his time in clearing out side-ditches which are too wet to be attended to except in dry weather, regulating the wastes, cutting weeds, and doing such repairs to culverts, drains, and other works on the road as may be necessary. He may break stone by contract or otherwise, or he may be permitted to work away from his road. The autumn work on roads is generally commenced after harvest, as the additional men which are required are then more easily to be had. Cleaning up the sides cannot be well done in dry weather, but the constant labourer should take advantage of suitable moist weather to get forward with it, so that the water-tables may be cleared, the outlets to the side- ditches opened, and the sod bordering trimmed before the wet weather sets in. If the manual labour be allowed to get behindhand in the autumn, there is often little chance of roads recovering it until the winter is over. Scraping is very neces- sary as soon as rainy weather commences, to get rid of the mud which then forms on the surface from the effects of the * Debauve, Manuel de I'lngemeur des Fonts et Chaussees ; Routes ; p. 191. MANUAL LABOUK. 137 wear in the summer. As soon as the cleaning up of the sides is finished, and the scraping is well forward, the laying of materials in small patches should begin. The first patches should be laid in places naturally damp, and when the road generally begins to soften from the wet weather, spreading materials and scraping will take up all the constant labourer's time, and usually rec[uire casual labour besides until the middle of December, or even later. In the beginning of the year, after the great bulk of materials has been spread, less labour is necessary : only small patches to make good weak places which have shown themselves during the winter remain to be laid, and scraping is hindered by frost, and by the unconsolidated materials about the road. As the spring advances more scraping will be required in damp weather, and ia dry weather the stones which have not worked in will require the roadman's attention, and must be raked off if they will not set. The spring and early summer is the best season for cleaning out side-ditches which are not too wet. The stuff is moved easier when stiU moist, and it is well to get forward with work of this sort in the spring, and not to leave it till the autumn, when there is so much other work to be done. Proportion of Expenditure on Materials and on Labour. The outlay on manual labour and the proportion which it should bear to that on materials are important points for con- sideration both in preparing estimates and in regulating expenditure on roads. A certain amount of labour expended on laying stones, and in attending to them afterwards, and on sufiicient care of the surface and under drainage, wiU be compensated for in the end by the saving in materials, and is therefore necessary for economy. The convenience of the public also has to be considered as far as possible, but while what is absolutely requii-ed for the good of the road is not neglected, labour should not be'wasted, nor be employed on useless or merely ornamental work. This is more particularly necessary when the funds are limited. Spending too much on labour for unnecessary or ornamental work, instead of on materials, is 138 THE MAINTENANCE OF MACADAMISED EOADS. often a great cause of weakness in roads, and a surveyor cannot be too careful in keeping the amount of labour down to the lowest point consistent with real economy. Of the manual labour employed on roads, one portion con- sists of work connected with the materials used, such as spreading stones, raking and attending to them while con- solidating, and removing the mud to which they are ultimately reduced. On a well-kept road the amount and cost of this labour depend almost entirely on the wear, the quantity of materials, and the care with which they are used. It takes more time to spread stones in small patches, with the care necessary for their ptoper and economical use, than to lay them in large quantities, or without after-attention ; and, if the traffic is light, and the material hard, more after-care is required than where the traffic quickly works in the stone. The removal of mud will also cost more as the scraping is more frequent. Another portion of the labour comprises work which is, to a great degree, independent of the wear and the quantity of materials used, such as cleaning the water-tables, trimming the sod bordering, opening outlets, clearing out side-ditches, and attending generally to the drainage. These naturally vary a good deal in amount and in proportion on roads differently situated, though they may be nearly constant on the same road under ordinary circumstances. Dividing thus the cost of labour, it appeared that on county roads iu South Wales on which 60 or 70 cube yards of materials were laid annually per mile, the average cost under the first head was from about Is. to Is. 7(?. per cube yard, and that under the second head, from about 3Z. 5s. to 42. 10s. per mile per year. The total cost of taanual labour thus approximately divided was from 71. 4s. to 91. Is. per mile of road per year, or from 2s. to toi2s. lOd. to a cubic yard of materials laid. These may be taken as the general averages for districts containiug 70 to 90 mUes of country main roads, on which the men were employed aU the year at wages ranging from 15s. to 18s. a week, and had the materials delivered on the roads by contract, ready broken. In districts where the labourers were not employed on the roads during the summer, or were preparing materials by contract. MANUAL LABOUR. 139 the labour was sometimes as low as 51. per mile per year, and in more populous districts it was as high as 151. per mile per year. In and near towns, the additional expense of frequent scraping, sweeping, and removing mud, more than counterbalances the saving in the labour of spreading when materials are laid in large quantities, and the cost of labour per mile is far greater. On the above roads, the cost of manual labour was generally from 30 to 40 per cent, of the combined cost of labour and materials, and sometimes a larger proportion (When the state of the finances demanded retrenchment in the amount of materials. When a large quantity of materials is laid down the cost of labour is- sometimes less in proportion. On parish roads in a highway district where the roads were well kept on the same system under a good surveyor, the manual labour cost about 41. or 51. per mile per year, which provided sufficient labour for the economical use of materials, and for the care of the surface of the roads according to their relative importance, and the proportion spent upon manual labour was from 37 to 42 per cent, of the combined cost of materials and labour. The returns of expenditure on turnpike roads and highways in England and Wales have not hitherto afforded trustworthy data from which either the actual or relative cost of manual labour and materials can be obtained. Other partial and scanty particulars appear to confirm the conclusion, to which observa- tion leads, that the road surveyors of this country generally trust to quantity of materials rather than care in their employ- ment. On the national roads of France, M. Dupuit estimated the manual labour connected with a cube yard of material at, on an average, rather more than one day's work. Other authorities give from J day to 1^ day per cube yard, and on the roads of the department of the Sarthe, under the system adopted by M. Dumas, which has been before alluded to, the labour on a cube yard of materials reached 5^ days' work. In a circular issued in 1850, fixing the bases on which the estimates for the national roads of each department were to be framed, and which was probably founded on the averages of all 140 THE MAINTENANCE OF MACADAMISED ROADS. France, the labour relative to the employment of a cube yard of material was given as 1 ■ 46 day's work, and the labour on accessory work as 64 days per mile, making together, for a road on which 60 cube yards of material per mile were used, a total of 152 days' manual labour per mile, which, at 2s. 6d. per day, would amount to 19Z. per mile. In 1860 it appears* that, on the departmental roads, the maintenance of which cost on the averageof the whole of France 281. per mile, the proportion per cent, of the cost of labour was 44, of materials 42, and of accessory works 14 of the whole. The labour per mile thus cost about 121. 6s. when wages were about Is. Qd. per day, equal to 20Z. 10s. per mile with wages at 2s. &d. a day, and a larger amount was spent on labour than on materials. From a report presented in 1879t it appears that in 1877 the mean amount of the labour employed on a cube yard of materials on the national roads was 1 ' 17 days, ranging from J or I days to as much as from 1| to 3 days in different depart- ments. On maintaining the sides, ditches, slopes, &c., the mean amount of labour was 62g^ days per mile, ranging from 24 to 46^ days in some departments, to 85 and 137 days in others. It is not evident to what these large differences, both in the amount of labour connected with the material, and that on sides, ditches, &c., are due. With reference to the latter it must be observed that much more work is generally done on the sides of the roads, which are often very wide, than is usual in this country. Other particulars of the actual and relative cost of manual labour wiU be given in the following chapter on the cost of road main- tenance. It is evident that very different results may follow according to the manner in which a given sum is expended on the maintenance of a road. Observation and local experience will guide an intelligent surveyor in partitioning the expenditure between materials and labour, but there are certain general principles always applicable. The chief care should be to replace the wear by a sufficient quantity of fresh materials, and * Documents statistiques sur les Routes et Fonts, 1873. t Aunales des Fonts et Chauss^es, 1879, vol. i., p. 316. MANUAL LABOUK. 14I 80 preserve what may be called the " capital value " of the road. When the funds are sufficient the only difficulty in maintaining this capital value lies in estimating the amount of wear which has to be compensated for by fresh materials, and this is generally done by experienced surveyors by observation and comparison, without the elaborate process of measurement before described. Eoads are, however, to be seen, with ample funds for their maintenance, and already quite strong enough, on which materials are laid year after year far more than sufficient to replace the wear, while the necessary labour is neglected. In such cases, .while the thickness of the coating is increasing, the surface is often full of holes and muddy, or covered with unconsolidated materials and loose stones, and a better road might be obtained by employing more manual labour judiciously, and reducing the quantity of materials, in most instances with a saving in the total cost, of maintenance. It generally happens that a limited amount has to be expended which must be apportioned to the best advantage. As a general rule, the greater the traffic is, the larger should be the proportion of the expenditure devoted to materials. Where the traffic is heavy, the full quantity of materials should be laid, even if the amount of labour has to be reduced to pay for it. The stones can be laid in larger sheets, and they will work in quickly with less attention than under lighter traffic. If, however, the quantity of materials be unduly increased at the expense of the manual labour, the spreading will be done with- out the proper care, and the surface work will be neglected, so that, while the road is getting thicker and stronger, it will also get rough and out of shape. The consolidation of the materials becomes besides a serious inconvenience to the traffic when more stones than can be readily worked in are spread without an adequate amount of labour. If, after the labour has been reduced as much as possible, the amount to be expended on materials is so small that the quantity will be insufficient to replace the wear, the road must of course get weaker, either by losing thickness or by contain- ing a less proportion of solid stone. But if the labour remains enough for the care of the surface, the road may even improve 142 THE MAINTENANCE OF MACADAMISED EOADS. in appearance while it is getting weaker, because there will be less materials to work in. Under the usual traffic, and with judgment on the part of the surveyor, this state of things may go on for several years without danger, more particularly if the road was originally strong. Thus take for instance a road on which the wear has been exactly replaced by 75 cube yards of materials to a mile. As 300 cube yards will coat a mile of road 5 yards wide one stone in thickness, 75 cube yards will coat one quarter of this surface, giving about | inch in thickness of consolidated road, which in the case supposed must represent the wear of four years, since the same part can only be coated once in four years, if the wear be supposed to be uniform over the whole surface ; ;| of | inch, or ^ inch, will therefore be the annual wear of surface, which has been replaced by 75 cube yards of materials per mile in the case supposed, the composition of the road remainiag the same, and thickness only being lost by wear. Suppose now that necessity causes the materials to be reduced from 75 to 60 cube yards per mile: then only one- fifth of the surface, instead of one-fourth, can be covered each year, and it will be five years instead of four years, before some part is coated, and in that time it wiU. have lost 5 x- ^g- or \^ inch of thickness, which will be replaced by f inch of con- solidated road ; -^g inch of thickness, or one year's wear will thus be lost in five years, supposing all the detritus resulting from wear to be removed, and the composition of the road- coating to remain unaltered. If scraping be not carried to this extent, the same amount of thickness wiU not be lost, but the road will contain more detritus. In practice the wear will not be uniform over the whole surface, and the materials will be laid by a good roadman where the surface shows signs of weak- ness ; but it is evident that for several years there will be no appreciable deterioration in the road. Nevertheless, it must not ' be lost sight of that the capital value of the road has been drawn upon to cover insufficient revenue, and if it be not replaced, the increased wear of materials which always takes place in a weak road will certainly begin to tell sooner or later, and a general break up under some extra traffic or unfavourable weather may happen when not expected. ( 143 ) CHAPTEE XL COST OF EGAD MAINTENANCE. The total cost of maintaining roads ranges between very wide limits. A road witli little traffic, well drained, and exposed to tlie sun and air, with, tolerably good materials at hand, can be kept in good order at a yearly cost of little more than ^ few pounds per mile for labour ; and a suburban road, or macadamised street, may cost many hundred pounds per mile per year. Unless the quantity of materials used, their price, and other particulars be taken into account, the cost per mile at which a road is maintained affords little real information, and may be mis- leading. The following particulars of the cost of maintaining macadamised roads are given with such details as are obtainable. , In 1856 it was stated* that the yearly maintenance of the road over "Westminster Bridge cost at the rate of 3300Z. per imle per year, the average wear of granite being 5^ inches. Eegent Street is stated to have cost at the rate of from 3400Z. to 3600Z. per mile per year, and the City Eoad 2300Z. per mUe, with an average wear of rather less than 3 inches of granite per year. The wear, however, was probably not measured, and what is given as such is most likely the thickness of the materials laid down. The cost of maintaining the macadamised roadway of Parliament Street was, for 1877, 2s. 9Jc?. per square yard, and for 1878, 3s. Id. ; Whitehall cost 2s. lOd. per square yard in 1877, and 3s. 2^d. in 1878. The average cost of maintaining King's Eoad, Chelsea, and Sloane Street, was stated to be at the same time 2s. Ud. per square yard per year, and in one portion which * Select Committee on Metropolis Roads ; Mr. Browse's evidence. 144 THE MAINTENANCE, OF MACADAMISED EOADS. is narrow as much as 6s. On the Chelsea Embankment, where the macadamised roadway is laid on a concrete foundation, 12 inches thick, the cost was said to be Is. Ad. per square yard per year.* The cost of the macadamised roadway in Park Lane and Knightsbridge is given as 3s. 6d., and Grosvenor Place and Buckingham Palace Eoad as 3s. per square yard.t In these cases Guernsey granite, at 16s to 18s. per cube yard, was the material used, and the cost of maintenance was exceptionally great. In a recent report by Mr. Santo Crimp the annual cost of the maintenance of the Victoria Embankment is stated to be :— Penis per eq. yd. Granite 9-00 Picking up, rolling, &o 4'40 Cleansing, and removing slop 9 • 43 Watering 1-00, Water 0-62 1-62 Sanding 0-55 25-00 or 2s. Id. per square yard, and the annual cost of seven other macadamised streets is given as from Is. S^d. to 2s. 6Jc?. per square yard. The cost of the macadamised surface of 13 of the Brighton streets, including some of the principal thoroughfares, was ascertained by Mr. Lockwood to be, in 1887, per square yard : — d. d. d. Repairs .. .. 0-69 to 13-42 .. .. average 7-11 Scavenging .. 2-78 „ 9-88 .. .. „ 5-23 12-34 Watering .. .. 0-57 „ 2-03 .. .. ,, 1-14 13 48 The total cost of repairs, scavenging, and watering ranged from 7 •27c?. to 24-07 per square yard in different streets. The 11 miles 5 furlongs of the Metropolis Eoads, north of the Thames, on the London side of the toll-gates, in 1856 cost at * Stajrton. Proo. Inst. Civil Engineers, vol. Iviii. p. 74. t Ellice-Clark „ „ „ p. 92. COST OF KOAD MAINTENANCE. 145 the rate of 1350Z. per mile per annum; the 53 miles within the limits of the Metropolis Local Management Act (including the above 11 miles 5 furlongs) cost at the rate of 761Z. per mile per year ; and the 68 miles beyond the same limits cost 268Z. per mile per year, exclusive of management, establishment charges, and toll-house repairs. It appears, from the annual reports of the commissioners, that the ordinary maintenance of the Metropolis roads north of the Thames, including water and watering roads, salaries, and establishment charges, was from 490?. to 620Z. per mile previous to the abandonment of the roads within the district of the Metropolis Local Management Act, in 1864, when from 470 to 580 cube yards per mile, principally of granite and hard stone, were used annually. Afterwards the annual cost for the remaining roads was 373Z. to 408Z. per mile, when from 380 to 470 cube yards of granite, hard stone, gravel, and flints per mile were used. The following are the details of the ordinary expenditure per mile of road in the last year, which included the maintenance of the roads within the Metropolis Local Management Act district, and in the last year in which the roads outside that district remained under the charge of the commissioners. Cost of Maintenance of Metropolis Roads per Mile. 1863-4. isn. £ s. £ 8. 93 3 71 13 133 6 65 8 274 2 177 9 16 4 , 12 15 25 8 14 3 32 12 31 3 £574 16 £372 11 Day labour, including men at the pumps during the watering season Digging gravel, and preparing materials by contract . . Team labour, including watering Materials, including freightage, wharfage, &c. . . . , Tradesmen's bills Rents of wharves and depots, taxes, water, Ughtingl gates, drain -pipes, and incidentals J Establishiiient, salaries, printing, stationery, advertisiug,| office expenses, &c ., / Total per mile . . 146 THE MAINTENANCE. OF MACADAMISED EOADS. Labour : Spreading, - Scraping, Ditches, &C. Per Cube Yard. •B CO eow OS O cq CD cq 00 ■S£ 5:S (-a OS CO O o o CO «» T-l i-H B°- , o CO CO oo f-1 1-t ■g ^ t- o i-l CO Ef ^ (M CO 1-H CO 1 |J 60 00 1-i r* CO cq g ^11 31 ^ (N t^ CO i-l CO 1 s i . o 00 C31 Oi CO to t^ to r-l (M t^ CO CO OJ 0-00 iHWi ^1 W ■-** OS 1-H il o5?0'*(Mioco. t>-co owi r^ lo Ot^OO OOrHin CTt-H OOCO lO U3 T-H I— I rH I-H I-H I— ( I— I (MCOCO OOO OlOO rH CD •fl " -^ -a " " a fe B • I ^ -^ S W |zi ^ O CO (M .s n O Eh J W !2i .s " tt p^ ^ Oh l:^ ^ HN i-fliM CD ^ iH i-t (as 60 U COST OF EOAD MAINTENANCE. 151 the surveyors of highway districts, at first under the author's supervision, and afterwards on the same system under Mr. J. Kirk, the cost of repairs per mile was, in 1880-81, 35Z. 2s., and in 1887-88, 34^. 6s., the average of the eight years being 34tl. 3s., including roads in urban sanitary districts and short lengths of town streets costing in one case llSl. per mile on the average. Excluding streets, the roads cost from 201. to 4:91. per mile per year in different highway districts, the materials being Clee Hill stone, limestone, and pebble stone. Labour cost 28 " 3 per cent, of the whole cost in 1881-2, gradually falling to 24 per cent, in 1887-88, when it was 8^. 2s. per mile. It ranged from 20*4 to 30 • 8 per cent, of the whole cost in different districts, the latter rate being in the district in which the roads were best and most economically maintained with Clee Hill stone, costing about 10s. per cube yard. The quantity of materials used varied in different highway districts from 32 to 45 cube yards per mile of Clee Hill stone, to 72 cube yards per mile of limestone, and in urban districts from 80 cube yards to 127 cube yards per mile of Clee Hill stone, and higher rates in streets. The average cost of the South Wales county roads, which represented the main roads in England and North Wales, as given above from the Parliamentary returns, is the cost of road repairs only, as in the case of the main roads. In 1877 the average cost of these roads, exclusive of salaries, management, and general superintendence, which averaged 31. 10s. per mile, was 24Z. 5s. per mile, where an average of 68^ cube yards of material per mile was used. The table opposite gives the cost of maintenance per mile for each county and district under the different heads of expenditure, together with the number of cube yards of materials laid, the cost of labour corresponding to a cube yard of materials laid, and the proportion of the cost of labour to the total cost of repairs. It will be observed that, comparing whole districts, the average cost of maintenance varies considerably, and if single roads, or parts of roads, were to be taken, the difference of cost would be far greater, some being as little as 51. per mile, while others with heavy traffic cost upwards of 3501. per mile for short lengths. 152 THE MAINTENANCE OF MACADAMISED EOADS. The wages were from 15s. per week in the cheaper counties, to 18s. or more in Glamorgan, and the cost of materials per cube yard ranged from 2s. 6d. in some parts of the cheaper counties to 8s. near Swansea. In Prance, in 1876, the maintenance of the macadamised national roads cost on an average 331. per mUe, of which 181. 6s. per mile, or 55^ per cent., was for materials, and 141. 14s. per mUe, or 44J per cent, was for labour. The average quantity of materials used was 78 cube yards per mUe, and the total labour per cube yard of materials cost on the average 3s. 9d:, being at the rate of IJ day per cube yard for the maintenance of the surface, and 64 days per mile for the labour on ditches, sides, etc. The mean rate of wages was Is. lOd. per day ; taking wages at 2s. &d. per day, the cost of labour per mUe would be 221. ; and per cube yard of materials used, 5s. Id. The cost of maintenance of course varied a good deal in different departments, the average in some being as low as 15Z. or 161. per mile, but in the majority the cost was not very far removed from the average. On the national roads of the department of Calvados, having an average traffic of 207 collars per day, in 1880, flint, sandstone, and quartz, having a mean coefficient of 13 "9, were employed, at the average rate of 86 cube yards per mile. The materials cost 301. 16s. per mile, or 7s. 2d. per cube yard on the average. The labour in spreading and attending to them cost Is. 6d per cube yard, and in removing mud and dust Is. lid. per cube yard ; together 3s. 5d. per cube yard of materials spread, or 141. 14s. per mUe. The labour on ditches, sides, etc., cost 71. 14s. per mile. The total average cost of maintaining the roads was thus 531. 4s. per mile, of which labour cost 221. 3s., or 42 per cent, of the whole. ( 153 ) CHAPTER XII. ROAD SUKVEYOK'S DUTIES. REPAIRS BY CONTRACT. ROAD MANAGEMENT. Road Surveyor's Duties. The general duties of a road surveyor will have been, to a great degree, gathered from what has preceded. The length of road that a surveyor can properly superintend depends upon many circumstances — the extent of country covered, the facilities for getting about by railway if he keeps no horse, and the amount of personal attention he is expected to give to details. If materials are supplied by contract ready broken, the surveyor is relieved of the superintendence of quarrying, carting, and breaking them, and has only to measure them, and see that they are properly broken after delivery on the road. He is thus able to superintend a greater length of road, but at the cost of the contractor's profit on the materials. If he has working foremen under him, or assistants, he can of course take charge of more road. Mr. McConnell, a gentleman of long and wide experience in superintending roads, gave it as his opinion* that a surveyor in charge of a district of roads so concentrated that he has not to go more than 10 mUes from home, and requiring for their main- tenance an expenditure varying from hi. to 40^, per mile per annum, having neither foremen, nor contractors, but himself letting work in detail to working men, ought not to have under his charge more than 60 miles of road, or 100 miles if he keeps a horse. In making this statement, a system of close superin- tendence is calculated on, and it is considered that the surveyor should inspect the greater part of his charge once in every week. * Letter from Mr. McConnell, Appendix to Report on Public Roads in Scotland, p. 80. 154 THE MAINTENANCE OF MACADAMISED KOADS. A surveyor who keeps a horse can do his duties much more effectually than without one, and more economically if his district can be proportionally enlarged. Thus, if a surveyor without a horse be paid l60l. a year, his salary on 60 miles of road will be 11. 13s. Ad. per mile ; with 50^. more for the keep of a horse, he can look after 100 miles for 11. 10s. per mile. In South Wales the county road surveyors superintended 86 , to 145 miles of roads, keeping horses, and having materials supplied by contract ready broken. The constant labourers, in permanent charge of their lengths of road, being generally long- tried and trustworthy men, were in some cases left to themselves more than would otherwise be desirable. The lengths of roads under one surveyor's charge in highway districts are generally from 100 to 200 miles, and sometimes as much as 300, or even upwards of 400 miles. Such long lengths as the latter cannot be properly looked after by one man, if much work is done on them, unless they are concentrated in a small area, and it is probable that many miles of the more unfrequented roads get little attention. Other circumstances than the length of roads in them govern the extent of highway areas, but whatever be tlie mileage put under the charge of one surveyor, the supervision should be effectual and constant, by ihe aid of assistants or working foremen if required. Great loss is sustained both in materi-al« -and labour by neglect, or the unwatched performance of the daily work on roads, and more especially so when there are not trustworthy constant labourers in charge. Surveyors of highways are required by the General Highway Act to keep accounts of the money received by them for the purposes of the highways, and of the manner in which they apply it, and they are liable to penalties for neglecting to do so. Under other circumstances a system which relieves the surveyor from payment of money gives him more time to attend to the work on his roads, and has other advantages. It may be arranged that all payments, whether wages or bills, shall be by drafts attached to vo\ichers prepared by the clerk from particulars furnished him by the surveyor, and signed by the chairman of the board, or other person authorised. Vouchers for payment KOAD SUEVEYOE'S DUTIES. 155 of bills are received by banks as cheques, and for the wages of labourers cheques or pay lists are sent either to the men or to convenient places for payment, and each man signs a receipt for the amount credited to him opposite his name in the sheet. No money thus passes through the surveyor's hands, and the clerk, if he does not actually keep the accounts, is responsible for them, and sees that no unauthorised payment is made. Fraud or peculation is impossible without collusion between the clerk and surveyor, and the keeping of proper accounts is rendered easier. A surveyor should always enter on ,the spot, with the date, a clear and distinct measurement of any work or materials which are to be paid for by measurement. A proper . book should be kept for the purpose, to be produced, if required, in case of dispute. To carry out a systematic renewal, year by year, of the materials worn out and removed as mud or dust, with strict accuracy, the amount of materials consumed, and the quantities supplied to replace them, must be known. The difficulties in the way of ascertaining the amount of wear of materials in a road have been noticed, and the surveyor must generally rest content with such an estimate of the amount required to replace it as observation and comparison may enable him to form. It is however, a simple matter to keep an account of the quantity of materials spread, and unless this be done, no intelligent system of maintenance is possible. The proper quantity to be included in the estimate for any one year, depends on that which has been spread in several previous years. The wear must be replaced, and the capital value of the road must be maintained, and if not to the full extent one year, it must be made up sooner or later, or the strength of the road will suffer. It often happens that the intentions of estimates are not carried out, materials destined for one road or portion of a road may be used elsewhere, or a reduction of the total quantity may become necessary for financial reasons. Comparisons of the amounts spread on various lengths of roads are also most useful and instructive. The excessive quantities of materials required to keep a badly drained piece of road in even tolerable condition, compared with other lengths exposed to the same traffic but more favourably situated, or the 156 THR MAINTENANCE OF MACADAMISED KOADS. contrast in the condition of similarly situated lengths of road with the same quantities of materials, when one is well attended to and another ill-kept, are thus made evident. As far as circumstances permit, account should be kept of the actual quantities of materials spread on every mile or short length of road. The road may be divided into well-defined sections of known length, each as far as possible of a uniform character throughout as to traffic, situation, &c., and the contracts for materials may be made with reference to these lengths. When the heaps of stone are measured by the surveyor after delivery on the roadside, their position should be noted, and the quantity delivered on each mile or short length may be recorded. When this has been done, it is easy to arrive at the quantity used. The road labourer may keep an account, which can be checked by the surveyor from the quantity delivered and remaining unexpended. The quantity used on each length should be reduced to cube yards of materials per mile of road, that comparison of one length with another may be easy. Statements of the quantities of materials received from contractors, or prepared under the surveyor, the quantities laid, and remaining, should be prepared every quarter. The account of the quantities laid ia the year may be conveniently made up for the financial year ending 31st March, as little material should be laid in the^ spring after that date. Eecords of materials used may be conveniently kept in the form of a diagram, the number of cube yards per mile being plotted to a suitable vertical scale along a horizontal line on which the years are marked. The history of a piece of road for many years is thus seen at a glance. An account should be kept of the tools, machines, and other property belonging to the road authority, showing where and in whose charge they are, and a statement of this account should be prepared annually. Annual estimates of the cost of road maintenance should be made in detail, showing the number of cube yards, price per cube yard, and the total cost of the road materials intended to be used, the cost of labour, and any miscellaneous expenditure that may be required beyond the ordinary maintenance, for every mile or less length of road. When the miles are not EOAD SUEVEYOR's DUTIES. 157 marked, the road should be divided into short well-defined sections of known length, which can be grouped together into larger divisions for recording the materials actually used. The form of estimate used for the county roads of South Wales is given in Appendix III. A summary of the cost of different roads or lengths of road included in the estimates may be afterwards prepared for general use, but detailed estimates should always be made in the first instance, whether they are required by the authority under which the surveyor acts or not. The estimates for the French national roads are prepared with an elaboration not attempted in this country. The coeffi- cient of quality of each kind of material used, and the quantity used per kilometre, and per 100 collars and 100 tons of traffic, are stated as well as the total cost when delivered on the road. Manual labour is dissected so as to show the amount and cost of it per cube metre for spreading and attending to the materials, and per kilometre of road for maintaining the sides, ditches, &c. The expenditure set forth in the annual estimate may be considerably modified by the state of the weather during the year. A wet season may demand a greater outlay, both on manual labour and on materials, and tax the skill of the surveyor to use the means at his disposal to the best advantage. A dry and favourable year, on the other hand, may allow of a considerable saving, or the full amount of the estimate may be spent on a reserve of materials. The accounts of expenditure should be kept in such a form as will show plainly what is spent on road repairs, i.e. on materials, on manual labour, on miscellaneous repairs to culverts and other works ; and what on salaries, law, management, and other establishment charges. The annual statements of expenditure on the South Wales county roads recorded this information for 40 years, giving the cost of road repairs under the separate heads of materials, labour, and miscellaneous repairs in each county and district, and on ninety separate lengths of road, apart from salaries and other establishment charges, and any special expenditure on improvements. There is no such record of the 158 THE MAINTENANCE OF MACADAMISED EOADS. cost of maintenance of either turnpike roads or highways in England, as from the manner in which the returns and abstracts were made they are useless as information regarding road main- tenance. In the turnpike accounts under the head of " manual labour/' payments to parishes, materials, and repairs by con- tract, were often included ; and under the head of " materials for surface repairs," contract work, team labour, &c. ; " tradesmen's bills," comprised repairs to works connected with the roads, toll- houses and gates, as well as stationery, printing, &c. ; and " incidental expenses " were made up of items of all sorts, whether road maintenance or establishment charges, watering and lighting, compensations, losses, &c. A similar confusion existed in the statements of the expenditure on highways. Surveyors of highway authorities are now required to keep accounts according to a prescribed form, which seems to have been framed for the convenience of audit rather than with a view to any useful statistical information. It is, however, quite possible, while keeping the books in the prescribed form, for a surveyor to embody all the information that will enable him to record for any length of road the quantity of material used, the cost of it when delivered on the road, the cost of manual labour on surface work, and of any miscellaneous expenditure not connected with the maintenance of the surface or works. This information is quite essential for maintenance on a proper system. Hepairs by Contract. The ordinary surface repairs of roads are sometimes let by contract, under the belief that men on day wages, and neces- sarily without close supervision, do not work as well as under a contractor. ' The advantages of repair contracts are doubtful, except in special cases, such as an outlying piece of road. Materials will often be carelessly used, and harm will arise from neglect and in other ways, unless the supervision is as close as a good roadman in charge of a length of road woiild generally require. Small contracts are the best, the roads being divided into sections of such a length that the contractor can himself superintend the work, acting as foreman over his men. The contract should be for a term of three to five years, terminable ROAD MANAGEMENT. 159 at the end of any year by three months' notice to the contractor, and in case of neglect to carry out the contract, the road authority should be empowered to perform the work and deduct the cost from the sum to be paid to the contractor. The con- tractor should be required to find sureties for the proper fulfil- ment of his contract. A specification of the work to be done and the mode of doing it must be prepared, setting forth the quantities of materials to be provided on each length of road, the nature of the stone, the size to which it is to be broken, and how it is to be spread. The contractor should be required to keep open and in good repair all drains and ditches, side channels, footpaths, mounds, borders, &c., and to scrape the road and remove the scrapings. It may be specified that the roa'd , shall be scraped whenever there is J inch of mud on it, and that the side channels shall be cleaned out after every scraping. Payments should be made periodically, by instalments, according to the work done, on the certificate of the surveyor. Boad Management. Large areas of road management have been often advocated, and they are attended with many advantages. Uniformity of system and maintenance on correct principles under the super- intendence of persons of wider experience than the ordinary road surveyor tend to economy in road repairs, and if the ex- penses of management are not less in proportion, as is usually the case, the total cost of maintenance is generally lower in large areas. There are facilities for generalising any improve- ment of practice, and it is easier to purchase machines, such as steam road rollers, horse scraping and sweeping machines, or stone- breaking machines, and to use them to advantage. A well-know instance of road management on a large scale is that of the Administration des Fonts et Chauss^es in France. The opportunities which such an organisation affords for investi- gation, and for collecting and generalising information, are shown by the documents issued by it,.and by the many valuable memoirs on the subjects connected with road maintenance contained in the ' Annales des Fonts et Chaussdes.' 160 THE MAINTENANCE OF MACADAMISED EOADS. Management by county areas has been general in Ireland since the Grand Jury Act of 1836, and with the best results as to the excellence and economy of rOad maintenance. In many of the counties of Scotland both turnpike and statute labour roads were under one management for many years, and by the Eoads and Bridges Act of 1878 the system of county manage- ment was extended to all parts of Scotland. In the Isle of Wight all public roads were for many years previous to 1889 under one management, with good results. In South Wales the turnpike roads of six counties were managed from 1845 to 1889 by county roads boards, aided by district boards for local purposes, and the whole of the roads, nearly 1000 miles in length, were, until 1882, under one general superintendent. A uniform system was thus established, com- bined with the advantages of local management, under which the roads compared very favourably, both for excellence and economy, with, other turnpike roads. The advantages of county management were in a measure extended to the ordinary hio-h- ways. Under the South Wales Highways Act of 1851, the whole of South Wales was divided into districts by the county roads boards, in whom were vested the appointment and dis- missal of the surveyors of the highway districts and the fixing of their salaries. Thus, the county roads boards had a certain control over the highway surveyors, which proved very beneficial. The Highways and Locomotives (Amendment) Act, 1878, enlarged the areas of road management in England in several important respects, and gave the county authority a control over the authorities of the highway areas, while leaving to them the duty of repairing the roads within their district. By Section 7 the repairs of aU roads within a highway district were made a common charge on all the parishes in the district, instead of being, as before, a separate charge in each parish. The enlargement of the area of chargeability was equitable, and there was a provision that a district might be divided with the approval of the county authorities into parts upon which to charge the expenses of the roads within them. The relief to parishes with more than their fair lencyth of roads ROAD MANAGEMENT. 161 was great, but it was otherwise with parishes with few roads in them, and they, to escape the increased highway rate, succeeded in some counties in breaking up the highway districts, of which there are now 56 less than in 1878. This retrograde step was possible because highway districts in England were not made general. By section 10, power is given to the county authority to en- force the performance of duty by defaulting highway authorities. By section 13, roads which, within the period between December 31, 1870, and the date of the passing of the Act, ceased to be turnpike roads, and any roads which had after- wards ceased to be such, are to be deemed main roads, and by section 15 the county authority may make an order declaring certain other highways to be main roads. It was further enacted that one-half of the expenses incurred by the highway authority in the maintenance of a main road should be paid to the highway authority by the county authority "out of the county rate, on the certificate of the surveyor of the county authority, or of such other person or persons as the county authority may appoint, to the effect that such main road has been maintained to his or their satisfaction." The power thus conferred upon • a central authority in each county had, when properly exercised, considerable influence over the maintenance of the main roads. The cost of such superin- tendence on the part of the county as would ensure maiutenance on proper principles and check improper charges, was generally recouped by the saving effected in the moiety of the cost paid out of the county rate, while economy of maintenance was accompanied by improvement ia the roads. The duty of maintaining the main roads of the county was, by the Local Government Act, 1888, transferred to the County Councils, except with respect to such roads as urban sanitary authorities claimed to retain. An opening for road manage- ment on a wider scale than has hitherto been possible in England is thus afforded, and one which, for the sake of economy and efl&ciency, it is to be hoped will be taken full advantage of. To do so it will be necessary to employ a staff of surveyors specially for, the main roads, acting under the superintendence M 162 THE MAINTENANCE OF MACADAMISED ROADS. of a county surveyor who would be responsible for the annual estimates of expenditure, and should besides carefuUy analyse and digest the actual expenditure, and record the quantities and nature of materials used on different roads or lengths of roads. The objection is sometimes raised that with one set of surveyors in charge of the main roads, and another set in charge of the ordinary highways, there would be two sets of surveyors going over the same ground, but this arises from an imperfect acquaintance with a road surveyor's work. He can only attend properly to such a mileage of roads as he can travel over often enough for proper supervision, whether they extend over the country or lie within a small area, and there need be no conflict of authority between the two sets of surveyors. There is none in France, where the national, the departmental, and the local roads have different organisa- tions ; and there was none in South Wales where there were separate surveyors for the highways and the county roads from the constitution of the highway districts in 1851 down to 188&. There was indeed a distinct advantage to the highway surveyors in having before them a pattern of good maintenance, and the highways benefited by it. The same result would follow in England. Instead of themselves maintaining the main roads, the County Councils may contract with a highway authority to perform the work, and they may require any highway authority to undertake the maintenance of the main roads, for a payment to be agreed upon or to be determined by arbitration. In either case the payment is to be made on the report , of the county surveyor that the roads have been properly maintained and repaired. Contracts of this sort, whether entered into voluntarily or on the requisition of County Councils, will, the author believes, prove unsatisfactory. In rural districts it wiU be almost impossible for the county surveyor to regulate, or even to know, what quantity of materials have been used on any road, and with parish surveyors the case wiU be still* more hopeless. In urban districts contracts may prove more prac- ticable. There must be a specification of the quantity and the nature of the material to be used on each length of road, of the ROAD MANAGEMENT. 163 manual labour, and all other work to be performed, and the amount to be paid for the specified work must be agreed on beforehand. But there must be also provision for the employ- ment of an extra quantity of materials and of labour, should the circumstances of the year demand it, and this will require very- careful arrangement. The necessity for records of annual expenditure, other than those required to be kept for the purpose of a money audit, has been pointed out. It is very desirable that counties should adopt some common form, showing plainly the cost of materials, of labour, and of any miscellaneous expenditure connected with the maintenance of the roads. Colnparisons of the total cost of different roads, and of the proportion of expenditure on materials and labour, and on other things, would be facilitated, and a step would be taken towards gathering statistics relating to road maintenance which are at present wanting in England. Sur- veyors and others interested in road management would then have the means of knowing how roads were maintained in other counties and districts, and of intelligent comparison of the cost. The effect would certainly be to promote economy of maintenance. M 2 164 THE MAINTENANCE OF MACADAMISED EOADS. CHAPTER XIII. EECAPITDLATION. It is evident that the maintenance of a road already in good condition and of sufficient strength, if properly carried on, is almost entirely a question of wear. With greater traffic, or a softer material, the wear will be faster, but with good maintenance there need be no deterioration. The problem is to reduce the wear, both from the traffic and the weather, to a minimum ; and to substitute other materials for those which are unavoidably worn out, and to do so in the most economical manner. The conditions under which the wear will be reduced to a minimum under a certain traffic are: good drainage of road and subsoil; materials sufficiently hard to resist the traffic without undue wear ; a coating without an excess of detritus ; a well-cared-for surface; and sufficient strength to bear the loads to which the road is subjected, so that wear may be confined to the surface. On very few roads are these conditions to be found, but their attainment should always be kept in view, and it is certain that in proportion as they are attained will be the economy of maintenance. Drainage almost always requires attention, and there is generally a good deal that can be done to improve it at a slight expense, and nothing pays so well in the end. Proper care of the surface is generally all that is wanted to prevent the water hanging about on the road, or in the side channels ; but a dry surface alone is not enough. On a flat, water may often be seen standing in the side-ditches up to within a few inches of the surface of the road, in which case both the subsoil and the road-coating are softened by the soaking of the KECAPITULATION. 165 water, and remain so long after the water in the ditches has fallen. A deeper ditch, a larger or a new culvert, or a drain cut through adjoining land, is generally sufficient to remove a cause of great mischief. Springs under the road, and land water from the side of a lull when the road is situated on a hillside, not properly cut off and led away, can often be thoroughly dealt with at a trifling cost compared with the expense they caUse. There is generally some choice of road materials to be had even from local sources of supply, and if that at hand is not strong enough to stand the traffic to which it is exposed, it will always be a question whether it will be more economical to go farther for a better material at an increased cost. The road-coating may often be improved in composition and rendered harder by scraping, and a tolerably good surface can be obtained under almost any disadvantages by proper attention to it. The influence which a good surface has in keeping down wear is greater than might be supposed with materials of all sorts, but particularly with those that are weak. Everjrthing should be done to render a road strong enough to bear the traffic to which it is subjected, without wear from bending or cross-breaking, and a reserve of strength is always of advantage. Fluctuations of traffic are most trying on roads which have no reserve of strength, and whenever there is reason to expect a large increase of traffic over a road, it should be strengthened beforehand for it, by adding materials. Otherwise, a larger quantity of materials wUl be required when the heavy traffic comes, which may cease before they are consolidated, and leave the road covered with loose stones, which wUl take a long time to work in under the usual traffic. A road may be strong enough for its ordinary traffic, and even have a considerable reserve of strength, and still be quite unable to stand the loads that may be brought upon it. When a road is thus broken down or cut into by excessive weights, it is no longer a matter of replacing wear, but of serious repairs, and it may be almost of reconstruction. It may be desirable that all roads should be rendered strong enough for 166 _ THE MAINTENANCE OF MACADAMISED EOADS. any traffic that may come upon them ; that will be a question of expense, but until they are so, it is unfair to expect a road to bear heavy loads which it is not intended for. It is as unreasonable to suppose that a road which is only moderately strong, though good, is fit to bear the traf&c of a traction engine and trucks, or heavy timber hauling, as it is to think that a heavy locomotive could be run on a light railway without seriously damaging it. To replace the wear which is unavoidable, economically, materials must be applied only where they are wanted, and with sufficient care both in spreading them and in attending to them afterwards, to ensure their being usefully employed. When the quantity to be laid is small, they must be applied in small patches where hollows or slacks of the surface show where they are required, and in thin coats. As the quantity to be spread is greater, so must be the size of the patches or sheets, , but they should never be niore than one stone in thickness when applied in this manner. After attention, to ensure the consolidation of the materials, will comprise raking and re-arranging stones, and, it may be, the use of binding, or even picking up round the edges in unfavourable circumstances ; and if, owing to the lateness of the season when they were spread, the stones will not set, economy of materials as well as public convenience may require that they should be raked off the road. If the wear be very large, say more than J inch of con- solidated road surface in a year, materials may be economically applied in thick coats with the aid of a roller, a thickness of 4 inches being laid down at once ; and this method, even when not economical, recommends itself to the public, because it spares them the annoyance of having to work in the stones by the ordinary traffic, and gives them at once a perfectly smooth road. There is perhaps nothing which is generally more neglected than the removal of the worn-out materials from the road. It appears to be often looked upon merely as a clearing of the surface from mud, and as such an unnecessary expense, while in reality it affects the composition of the whole road-coating. RECAPITULATION. 167 and unless the mud is washed away naturally from the surface, scraping or sweeping is quite necessary to preserve the proper proportion of solid stone in the road. Experiment has shown, what might have been expected from other considerations, that from one-fifth to one-fourth of the whole bulk of a road- coating must necessarily be small stuff under L inch ia diameter, which moisture will convert into mud, and it is certain that, as this proportion is exceeded, so will the road be soft, easily acted on by traffic, wet, and frost, and wasteful of materials. An adequate amount of manual labour in laying materials, scraping, and attention to the surface, is quite necessary. It is no real economy to save in labour, while more is spent on materials with a worse result. At the same time there is always the danger of too great an expenditure on manual labour. Work may be performed which, without being altogether useless, is unnecessary or not worth its cost, or much time may be absolutely wasted. Experience shows that the expenditure on the manual labour employed on surface work under ordinary circumstances may with advantage amount to 30 or 40 per cent. of the combined cost of materials and labour, but no fixed proportion can be laid down, and the employment of the proper amount of labour, and its economical adjustment to particular circumstances, will always require considerable care. The advantages arising from having men in charge of certain lengths of road cannot be too much insisted upon. Even if a man is not constantly employed on the surface work of the road, but is engaged in stone-breaking or harvest- work during the summer, he becomes familiar with the peculiarities of his length, and with the best way to deal with them, and if he is a good workman, he soon learns to take an interest in the road which it is his business to keep in order. It is in vain to expect the same skill or industry from men employed by the job, or having no interest in the goodness of the road, or in making the most of the means at their disposal. Expenditure on road maintenance has often to be reduced below what is desirable that it may not exceed a certain amount, and skill and judgment are then required to use the limited 168 THE MAINTENANCE OF MACADAMISED ROADS. amount to the best advantage. Manual labour must be reduced, that sufficient materials may be employed, and if materials enough to replace the wear cannot be afforded, it must not be forgotten that the strength of the road is being drawn upon, and that in however good a state it may be, it will certainly deteriorate to a condition which will demand extensive repairs, unless the loss of materials be made good in time. It has been shown, however, that the process of deterioration is a gradual one in a road originally strong enough when it is sknfuUy managed, and a careful surveyor can therefore tide over several years of reduced expenditure without much danger to his roads. He win watch how far different portions are losing strength, and to what extent wear is consequently augmenting, and he will not let matters go too far. In more favourable times a reserve of strength may be laid up by adding more materials than the wear consumes, which, by increasing the strength, will also lessen the wear of the road, and in the end tend to economy. Care in the preparation of estimates, and in accounts of the actual expenditure on different roads, year by year, are both equally necessary. A good deal of examination and comparison of expenditure under different heads, on different roads and portions of roads, will be found useful. All expenditure on road repairs should be kept distinct from the cost of management, and the manual labour employed on the surface work of the roads should, as far as possible, be separated from that which is properly a part of the cost of materials, such as stone-breaking or quarrying. A careful account of the quantities of materials spread year by year on each road and portion of road, is essential to systematic road maintenance. It constitutes a record of the strength of each road, and when reduced to the rate of cube yards per mile of road, the quantities used on different roads are readily compared. Comparisons of traffic and wear are much easier than absolute measurements, and it is by such comparisons, and records of the quantities of materials used, and of the expenditure on manual labour, &c., on various roads, that an opinion must generally be formed of the economy with which EECAPITULATlON. 169 they are maintained, and of the requirements of any particular road. Due allowance must, of course, be made for difference in materials, situation, and other conditions, and regard must be had to the state in which the roads are kept, but when comparisons are possible over considerable areas, they are less influenced by minor differences. Hitherto the materials for an intelligent comparison of expenditure on road maintenance have been wanting in England, but it is to be hoped that one effect of county management of main roads will be to provide them. That good results, both as to economy and efficiency, would follow cannot be doubted. ( 170 ) APPENDIX I. FONTS ET CHAUSS:]feES. Eegulations for CantonnieRs. Art. 1. — Definition of the Work of Cantonniers. The cantonniers are charged with the manual labour connected with the daily maintenance of the roads, over a definite length of road called a canton. They must obey, in everything relating to their work, the engineers, foremen, and other agents of the administration of roads and bridges. Art. 2. — Nomination of Cantonniers. The cantonniers are nominated by the prefect, from a list sub- mitted by the chief engineer, containing three times, or at least twice the number of candidates required to fill the vacancies. They are dismissed by the prefect on the proposal or advice of the chief engineer. Art. 3. — Conditions of Admission. To be nominated a cantonnier it is necessary (1) to have fulfilled the laws relating to service in the army, and to be not more than 45 years old ; (2) not to be subject to any infirmity which may hinder daily and diligent labour; (3) to have worked on the construc- tion or repair of roads ; (4) to have a certificate of good conduct from the mayor of the commune or the sub-prefect of the arrondissement. Candidates who can read and write will be preferred. Art. 4. — Chief Cantonnier. The cantons of the roads in a department shall be gtouped in districts containing at least six cantons; the six cantonniers will constitute a brigade ; one of them shall be chief cantonnier ; he must APPENDIX. 171 be able to read and write, and shall be chosen from the cantonniers distinguished for zeal, good conduct, and intelligence. The chief cantonniers shall have a shorter length than other cantonniers, so that they may be able to attend to special duties allotted to them. They shall accompany the foremen in their rounds, and note the orders which may be given to the cantonniers of their brigade, and see that the orders are carried out. They shall accordingly go over the whole extent of their district at least once a week, varying the days and hours of their visits, to satisfy them- selves of the presence of the cantonniers, and to direct them in their work ; they shall report to those under whose orders they are more particularly placed, and shall furnish to the engineers all the in- formation that may be required of them. They may be temporarily employed in superintending and keeping account of the works of re-dressing the paved causeways, and in directing itinerant gangs of workmen. Art. 5. — Distinctive Marks of Cantonniers. Cantonniers shall wear a blue jacket and a leather hat, round which shall be a band of copper • 28 m. long, and • 055 m. broad, with the word " cantonnier " cut out in it. The chief cantonniers shall wear besides on the left arm an armlet of the prescribed pattern. There shall be given besides to each man a mark consisting of a staff 2 metres long, divided in decimetres, shod with iron, and fur- nished at the top with a strong iron plate 0* 24 m. wide, and • 16 m. high, on each side of which shall be shown in letters • 08 m. high the number of the canton. This mark must always be set up on the road at less than 100 metres from where the cantonnier is at work. Art. 6. — The Work of the Cantonniers. The work of the cantonniers consists in maintaining and repair- ing the roads daily and constantly, so that they may be dry, clean, and smooth, safe in times of hard frost, and of a satisfactory appear- ance at all seasons. To effect this, they must, subject to the orders and instructions which may be given them in case of need : (1) Insure the flowing off of water by cleansing the gutters, pipes, &c., by making small drains for the ptirpose wherever they may be necessary, taking care that these drains should never be made in the body of the road. 172 APPENDIX. (2) At suitable times open and maintain the ditches, regulate the sides, throwing the surplus earth on the neighbouring ground, if there is no objection, or putting it together to facilitate its measurement or removal. (3) Eemove as soon as possible with a scraper or shovel, all liquid or soft mud from the whole breadth of the road, even if there be neither hollows nor ruts, and collect the mud in regular heaps on the sides to be measured, if there is room for it there. (4) Spread the mud, when dry, on the sides which have lost their shape or have a slope of more than 1 in 25 from the road, and throw the surplus on the neighbouring fields, if not objected to. (5) At the approach of winter redouble attention to all which is prescribed in the two preceding paragraphs, to prevent lumps of frozen mud. (6) In dry weather, remove the dust and deposit it on the sides. (7) Clear away the snow from the whole breadth of the road, or at least from the middle, particularly at places where it accumulates and obstructs the trafi&c ; throw it immediately on the neighbouring fields if possible, or collect it in heaps on the sides, so as to show drivers of vehicles where the road is. (8) Break and remove ice from the road, and scatter sand and rubble, especially at the sides and at sharp turnings. (9) Also break the ice in the ditches and remove it where it accumulates so as to threaten flooding of the road in the thaw. (10) In the time of thaw assist the flowing off of water and remove pieces of ice, mud, and dirt, so that the effects of the thaw may prejudice the traffic and the road as little as possible. (11) Collect, break, and stack in separate heaps and in a par- ticular shape, all loose stones, and those projecting or only just showing if too large, and those near in the neighbouring fields which can be used for the purposes of the road. Break the materials intended for maintenance if the breaking is not done by the contractor. (12) Cut or dig up thistles or other weeds, especially before their flowering season. (13) Clear away loose stones from the road and every thing which may hinder the traffic. (14) Clean and clear away earth, plants, and extraneous matters from the plinths, string courses, and parapets of bridges, &c. (15) Look after the preservation of mile stones, sign posts, and bench marks on the road. (16) Cultivate and look after plantations belonging to the State, APPENDIX. 173 see to their preservation and to that of plantations of private owners, straighten provisionally all young trees bent by the wind, and do generally all that the welfare of the road demands, conformable to more particular instructions given by the engineers of the district for carrying out the above general orders. Art. 7. — Employment of Materials. On roads in a state of repair the road labourers shall conform to the following rules for employment of materials. The materials shall be made use of as they are required, always choosing damp weather for their employment, avoiding wholesale coating and throwing down stones at random. To proceed regularly, care should be taken to observe in time of rain the hollows and tracks of vehicles which perceptibly alter the shape of the road. These worn parts should be cleaned and picked, particularly at the edges, but only to the depth necessary to insure the binding of the materials. The materials arising from the picking should be cleared of earth and broken if necessary before being used. The filling up of the hollows or wheel tracks should be eifected with the debris and with the necessary quantity of new material received through the engineer. It must be carefully beaten so as to incorporate it with the lower layer, and then made even with the form of the road. The parts thus restored should be maintained with particular care until they are completely consolidated. . With respect to roads which are not in a good state of repair, and which nevertheless are open for traffic, one should endeavour to keep them in as good a condition as possible by employing with the care which has just been indicated the materials available. All stones too large or projecting should be taken out, as they cause damage, and they should be broken to a proper size before being used again. The coatings more or less extensive to be made on worn roads will be prescribed by the engineer, who will also decide on the materials to be used. The hollows and ruts to be filled up must first be cleared of mud and earth, and their surface then picked to a depth of from 4 to 5 centimetres (1^ to 2 inches). The materials should not be spread except in layers of from 5 to 6 centimetres (2 to 2^ inches), which should be carefully beaten and consolidated. 174 APPENDIX. Art. 8. — Task Work to be Performed. To excite and maintain the activity of the cantonniers, the engineers, inspectors, and foremen shall assign them work to be perfonned in a given time, whenever local circumstances permit it. A summary of information on these tasks shall be entered in that part of the ' cantonnier's book reserved for the orders of the service. Works thus prescribed shall be one of the principal objects of supervision by the immediate head of the cantonniers, as well as by the mayors and road commissioners. Art. 9. — Determination of Working Hows. From the 1st of May to the 1st September, the cantonniers shall be on the roads, without quitting them, from 5 o'clock in the morning to 7 o'clock in the evening. The rest of the year they shall be there from sunrise to sunset. They shall take their meals on the road at hours fixed by the chief engineer. The total duration of meals shall not exceed two hours, but during great heat it may be prolonged to three hours. Art. 10. — Rerrwval of Cantonniers. Cantonniers may be moved, either singly or in brigades, when the needs of the service imperatively require it, to be directed to points indicated to them. These displacements shall not take place except under an express order from the engineer. Art. 11. — Compulsory Attendance of Cantonniers in time of Bain, Snow, &e. Rain, snow, or other inclemency of the weather shall not be a pretext for the absence of cantonniers ; they must, in such times, redouble their zeal and activity to prevent damage and keep the road in good condition for the whole extent of their cantons ; they are, however, authorised to make themselves fixed or portable shelters, which shall not interfere with the public way or adjoining property, and which must be in sight of the road, and less than 10 metres off, so that the presence of the workmen can always be ascertained. APPENDIX. 175 Art. 12. — Gratuitms Assistance to Travellers. Cantonniers must render gratuitous aid and assistance to drivers and travellers, but only in case of accidents. Art. 13. — Surveillance over breaches of Highway Law. To prevent as much as possible breaches of highway law, the cantonniers shall warn frontagers who may be disposed to commit them. They shall consequently keep an eye on repairs, building, deposits, encroachments, and planting which may take place without leave on the highway. They shall report any such breaches to the surveyor, either when he makes his rounds, or at once by letter or by message through the chief cantonnier. Art. 14. — Tools with which Cantonniers must be provided. Every cantonnier shall be provided, at his own expense, with a wheelbarrow, an iron shovel, a wooden shovel, a road-pick, an iron road-scraper, a wooden road-scraper, an iron rake, an iron crowbar, an iron sledge-hammer, and a line 20 metres long. The head cantonniers must besides be provided with three boning rods, with a level graduated to indicate gradients, and with a double metre measure. Art. 1 5. — Tools of a particular kind to be furnished by the Administration. Each cantonnier shall be entrusted with an iron ring, 6 centi- metres (2^ inches) in diameter, so that he may ascertain if the stones which he has to spread on the road, have been broken according to the specification. Art. 16. — Providing Tools in advance to Cantonniers. Cantonniers who have no means of procuring them, can have any tools they require supplied in advance. The repayment of the cost of these tools will be insured by the administration, by stoppages, which, except in cases of dismissal, shall not exceed one-sixth of the monthly salary. Art. 17. — Keeping Tools in Repair. Cantonniers shall keep their tools in a good state of repair. If they become negligent in this respect it will be done by the admi- nistration, and the expenses will be repaid as stated in Art. 16. 176 APPENDIX. Tools must not be taken to be repaired during working hours. Excuses for absence based upon the necessity' of getting tools repaired will never be accepted. Art. 18. — Cantormier's Boohs. Every cantonnier will be provided with a book similar to the one annexed to the present regulations. This book is intended to receive notes on the work and conduct of the labourers, any orders and instructions given them, and information of the work which has been assigned them. It must be presented by them to the agents charged with the supervision of the road, every time they are required to do so, under penalty of the stoppage of a day's pay for every time they neglect to produce it, or of three days' pay in the case of having lost it. Art. 19. — Means of verifying the Absence of Oa/ntonniers. The absence and negligences of cantonniers will be verified by the engineers and the agents of the administration employed under their orders, who will make a note of them in the books just spoken of. Absence can also be verified by gendarmes on their rounds, by mayors' of the parishes in which the cantons are situated, and by road commissioners. Art. 20. — Leave of Absence at Harvest Time. At harvest time, when the road is in good condition, cantonniers can obtain leave of absence from the engineer in ordinary, when authorised by the engineer in chief. They will receive no salary while on leave of absence, at the expiration of which they must returned punctually to their posts, or they will be immediately superseded. Art. 21. — Surrender of Booh and of Distinctive Badges on Dismissal of When a cantonnier is dismissed, he must surrender to the engineer his book, his stafii his ring, and the distinctive badges which he wears on his- arm and cap. Failing to do this, double the value of these articles will be retained from that which is due to him for salary at the time of his dismissal. APPENDIX. 177 Art. 22. — Classification and Salary of Cantonniers. Cantonniers of each department will be divided into three classes of equal number, whose salary, for each class, will be fixed by the prefect, on the proposal of the chief engineer. The classification will be made each year by the chief engineer, on the report of the engineer in ordinary, and according to the services of the cantonniers during the preceding year. The chief cantonniers will be divided into two classes, likewise of equal number. Their salaries will be fixed, like those of the ordinary cantonniers, by the prefect, on the proposal of the chief engineer. Art. "3.— Indemnity for Bemoval. Cantonniers who leave their cantons by order of the engineer Will receive an indemnity of one-fifth more than their salary, and three- fifths for every day they sleep out. No indemnity for removal will be allowed to head cantonniers except when they go out of the district of their brigade. In this case, the indemnity to which they are entitled will be regulated in the same way as those which are paid to ordinary cantonniers^ Art. 24. — Annual Gratuities. Every year, on the report of the engineer in chief, the prefect may grant to the most deserving cantonnier in each district of the engineer in ordinary, ^ gratuity, which shall not exceed a month's salary. A similar gratuity may also be awarded to that one of the chief cantonniers of the department, who shall have rendered the best service. Art. 25. — Fines on Account of Absence. Every cantonnier who shall not be found at his post by one of the agents having a right of supervision on the road, shall be subject to a fine of three days' pay for the first time, of six days' in case of a second ofience, and be dismissed the third time. Those who, without being absent, shall not have done enough work during the month, or who have neglected the duty entrusted to them, ■ft'ill be fined enough to pay for repairing any damage resulting from their negligence. A part of these fines may be granted by the chief engineer, on the report of the engineer in ordinary, for the benefit of those can- tonniers who by their zeal and work have deserved encouragement. ( 178 ) APPENDIX II. (FoKM OF EoAD Labourer's Jotjrnal.) Roads, Diary of _ District. _, Constant Labourer, for week ending Saturday, 18 Open to the inspection of every member of the County or District Boards Board. Date. Description of Work. Snrveyor's Minute of his Visit, and the Work he found the Labourer engaged on. Spreading Stones. Baking Stones. Scraping. Siding. Other Works. M. T. W. T. F. S. APPENDIX. 179 Pi 1— ( I hi o a M O I N and Eeport respecting the Casual Labour, and Miscellaneous Bxpendlture anticipated. (As full explanation as possible should be given of the reasons for which the several sums are required.) Total. £ «. d. MiBcella' neous. £ ». d. % Casual. £ 8. d. Constant. £ e. d. i 1 Amount. •pi aquo jad saouj: •Bpi aquo ■suraqo •sSuoiin^ •sauH N 2 ( 181 ) INDEX. A. Accounts of expenditure, 154-158 , common form desirable, 163 Act, General Highway, 5, 11, 36, 119 i Highways Act Amendment, 37 Highways and Locomotives Amend- ment (1878), 125, 160 South Wales Highway, 5, 37, 160 Action of weather, 82 Analyses of road coatings, 54 Annual estimates, 156 , form of, 179 Archer's stone-breaHng machine, 43 Area covered by a cube yard of broken stone, 41 Arrangement of labour, 136 Attention to materials when spread, 101 Autumn work on roads, 136 Axle, friction of wheel on, 59 B. Baedonnaut, M., 52, 87 Bayley's hydrostatic vans, 122 Bending and cross-breaking, wear from, 76-80 Berthault-Duoreux, M., 49, 52, 53 Binding material, 23-25, 100 property of limestone, 83 Blake's stone-breaking machine, 42-45 Block stones, 128 Bolkelberg's experiments on broken stone, 49 Bordering, sod, 18 , trimming, 117 Bottoming, 3-7 of sand, gravel, or chalk, 15 Breadth of metalled surface, 18 wheel tires, 64-68 Breaking stone by hand, 41 by machinery, 42 , cost of, 44-47 Breconshire, county roads, cost of main- tenance, 150 , cost of labour on, 150 Breconshire, county roads, quantity of material used on, 94, 150 Brighton streets, cost of, 144 Broken stone, proportion of solid and void in, 49-51 , weight of, 50 road, construction of, 17 Burgoyne, Sir J. F., 21, 104 C. Oantonniees, regulations for, 170-177 Cardiganshire county roads, cost of main- tenance of, 150 — '■ , cost of labour on, 150 , quantity of materials used on, 94, 150 Carmarthenshire county roads, cost of maintenance of, 150 , cost of haulage of materials on, 47 labour on, 150 cost of -, quantity of materials used on, 93, 150 Carting, cost of, 47 materials from atone heaps to road, 39,99 Carts, water, 121 Channel, side, 13, 18, 117 , pitched, 19 Chlorides, use of, in watering roads, 123 Cleaning sides, 117 Clearing out side ditches, 118-119 Coating, road, composition of, 49-58 , thickness of, 17 , effect of, 78 Coatings, road, analyses of, 54 , experiments with model wheels on, 77-99 -, proportion of mud in, 56 -, proportion of various sizes of stone in, 56 CoeflSoients of quality of road materials, 33-36 182 INDEX. Collars, traffic measured by, 85 Comparisons of quantities of materials laid, 155 Composition of road coatings, 49-58 scrapings, 57 Concrete foundations, 16 • Conditions under which wear will be reduced to a minimum, 164 Conical wheels, 64 Consolidated road, density of, 52 Constant labourers, 129 , lengths of road under. 134 , premiums to, 132 , duties of, 129-133 Consumption of materials, 90-94 Contract, repairs by, 158 Copper slag as a road material, 31, 54 Cost of carting, 47 kerbing and channelling, 19 manual labour, 138-140, 147, 150 per cube yard of materials used, 188, 139, 150 mUe, 138-140, 150 lifting, 29 macadamised roads, 25 picking up, 100 quarrying, 46 repairing damages by traction engines, 125 repairs of main roads, 149 road maintenance on Edinburgh turnpike roads, 146 county roads, 150 road materials, 46 rolling, 107, 108 - stacking, 46 - South Wales stocking up, 100 stone-breaking by hand, 41 machinery, 42- 45 watering, 121 wheeling out materials, 47 Covered drains, 10, 11 Crimp, Mr. S., 121, 144 Cross-breaking, wear from, 76-80 drains, 11 sections of roads, 12-14 Culverts, examination of, 126 , inclination of, 11 , obstruction of, 126 , undermining of, 126 Cutting hedges, 119 D. Deacon, Mr., 24 Density of consolidated road, 52 Depots, stone, 21, 99 Detritus, effect of, on wear of roads, 90 , French gauge for, 53 , measurement of, 88 Diameter of wheels, effects of, 59, 73, 78 Dished wheels, 64 Ditches, side, 10 , clearing out, 118 , water-level to be kept low in, 118 Drainage, 10-12, 116-119 , importance of, 116, 164 , powers with respect to, 11, 119 Drains, examination of, 118, 126 , inclination of, 12 Draught, 59-63 , effect of springs on, 63 , large wheels favourable to, 60 , Macneill's experiments on, 62 ■, Morin's experiments on, 61, 63 -, proportion of, to load, 61-63 Dumas, M., his system, 103 Dupuit, M., 59, 87, 189 Durability of materialsj relative, 33 Dust, removal of, 110 E. Edgbworth, Mr., 59 Edinburgh, turnpike roads of county of, cost of maintenance of, 146 , cost of materials, 47, 146 , quan- tities of materials used, 93, 146 Engines, traction, 67, 80 , repair of damage by, 125 England and Wales,- cost of repairs of main roads, 149 - of roads, formerly turnpike, 148 of turnpike roads, 148 , expenditure on roads, 2 Estimates, annual, 156 , form of, 179 Expenditure, accounts of, 157 on materials and labour, 187- 142 roads of England and Wales, 2 Experiments on draught at Boyal Agri- cultural Show, 60, 61 by Maoneill, 62 by Morin, 63 on wear by Morin, 73-76 with model wheels on model road-coatings, 77-79 Extraordinary traffic, 125 INDEX. 183 Feet of horses, wear by, 69 Fences, 20 Field stone, 32 Flint gravel, 32 Flints, 32 Footpath, 20 Foremen, working, 133 Formation of surface, 15 Foundation, concrete, 16 , pitched, 15 , thickness of, 16 France, consumption of road materials in, 90,91 -, cost of labour on departmental roads of, 140 139 national roads of. maintenance of national roads in, 15^ Friction of wheel on axle, 59 Frost and thaw, effect of, 82 , repair of road broken up by, 124 G. Gaspabin, M., 50, 52 Gauge for broken stone, 39 detritus in France, 53 General Highway Act, 5, 11, 36, 119 Glamorganshire county roads, cost of maintenance of, 150 , cost of labour on, 150 -, quantity of materials used on, 93, 150 Grseff, M., 52, 89, 106 Gravel bottoming, 15 , weight of, 51 Gravity, resistance due to, 60 H. Hammers, 41 Hand scraping machines, 112 Harness, Sir H. D., 131 Haulage, cost of, 47 Heaps, stone, 38 , carting from, to road, 39 Heavy loads, effects of, 125 Hedges and trees, ill effects of, 83, 119 , cutting of, 120 Highway Act, General, 5, 11, 36, 119 Highways Act Amendment Act, 37 Highways and Locomotives (Amend- ment) Act, 125, 160 Holes in road coating, repair of, 124 Hollows on surface, form of, 97 , repair of, 98 Holyhead road, 14, 92, 99, 129 , cross sections of, 14 , pitched bottom on, 14 Hope's stone-breaking machine, 43 Horse road rollers, 21 Horses' feet, wear by, 69 Hydrostatic vans, Bayley's, 122 Inclination of drains and culverts, 12 K. Kbebing, 19 , cost of, 19 Labocb, manual, 129-142 , proportion of expenditure on, 137 , cost of, 138-140, 150 , per cube yard of material, 139 Labourers, assistant or casual, 135 , constant 129 duties of, 129-133 , lengths of road under, 134 , premiums to, 132 , journal to be ^ept by, 133, 178 , stone-breaking by, 41 , tools used by, 134 Large wheels, advantageous to road, 73 , favourable to draft, 60 Leahy, Mr., 50 Length of road that surveyors can super- intend, 153 under constant labourers, 134 Level, road, 134 Lifting, 28, 29 , cost of, 29 Limestone, 33 , binding property of, 31 Load, effects of, on wear, 75, 80 , proportion of draught to, 61-63 Loads on wheels, 65-68 , subsoil yielding under, 76 London streets, wear of, 92 Lopping trees, 120 Lovegrove, Mr., 108 M. McAuAM, J. L., 3, 7, 17, 21, 28, 39, 99 , Sir James, 25, 67, 69, 130 Macadamised roads, cost of, 25 McOonnell, Mr., 153 Machines, scraping. 111 , hand scraping, 112 , stone-breaking, 42-47 184 INDEX. Machines, sweeping, 111 Maoneill, Sir John, 16, 62, 63, 66, 68 , experiments on traction, 62 Main roads, cost of repairs, 149 , common form of accounts desirable for, 163 Maintenance, road, cost of, 143-152 Management, road, 159-163 Manual labour, 129-142. {See also Labour.) Materials, road, 30-39 and labour, proportion of expen- diture on, 137-142 , area covered by a cube yard of, 41 , attention to, when spread, 101 , coefficients of quality of, 33-36 — , consumption of, 90-94 , cost of, 46 -, cost of labour per cube yard of. 138, 139, 150 , cost of, on Edinburgh turnpike roads, 146 , cost of wheeling out, 47 , power to get, 36 , quantities used, 91-94 , ramming, 101 , size of, 39 , spreading, 95-104 •-, season for, 102 -, supply of, 37 ■ used on roads, records of quan- tities of, 166 Measurements of detritus, 88 , traffic, 85-87 , wear, 87, 88 Merrifield, Mr., 49 Metalled surface, narrowing, 127 , width of, 18 Metropolis roads north of Thames, cost of repairs of, 145 Metropolis roads north of the Thames, quantities of material used on, 92 Mitchell, Mr. J., 50 Mitre drains, 11 Model wheels, experiments with, 77-79 Morin, General, 59, 60, 61, 72, 73 , experiments on draught by, 61 wear, 73-76 Mound or bank fences, 20 Mud, proportion of, in road coatings, 54-58 N. Narrow tires, 68, 81 Narrowing an over-wide road, 127 National roads of France, cost of labour on, 139 , cost of main- tenance of, 152 O. Obstruction of culverts and drains, 126 Obstructions on roads, 1 27 Old road, re-forming, 26 Outlets, 20, 116 , clearing, 117 Parliament Street, cost of road repairs in, 143 , traffic in, 87 Patches, shape and arrangement of, 97 Paved foundation. (See Pitched.) Payment by vouchers, 154 Pembrokeshire county roads, cost of main- tenance of, 150 , cost of labour on, 150 , quantity of materials used on, 94, 150 Penfold, Mr., 16, 32 Piccadilly, traffic in, 87 Picking up, 99 , cost of, 100 Pitched bottom on Holyhead road, 14 foundation, construction of, 15 Pitting or sounding, 27 Post and rail fence, 20 Powers to get materials, 36 with respect to drainage of roads, 11, 119 Premiums to constant labourers, 132 Pressure per inch of width of tires, 65-67 Proportion of draught to load, 61-63 expenditure on materials and labour, 137 mud in road coatings, 51-58 — scrapings in roads, 57 solid and void in broken stone, 49, 50 • various sizes of stone in road coatings, 54, 55 Q. Qualifioations of good road stone, 30 Quality of road materials, coefficients of, 34-36 Quantities of road materials used, 90-94 stone broken in a day, 41 Quarrying, cost of, 46 R. Kadnorshire county roads, cost of main- tenance of, 150 , cost of labour on, 150 INDEX. 185 Radnorshire county roads, quantity of materials used on, 94 Rain, effects of, 82 Raking, 101 Ramming materials, 101 Recapitulation, 164-169 Records of quantities of materials used on roads, 156 Re-forming an old road, 26 Regent Street, cost of road repairs in, 143 Regulations for cantonniers, 170-177 Relative durability of materials, 33 Removal of dust and mud, 110-115 Repair of damage by traction engines, &o., 125 damage done by traction en- gines, cost of, 125 holes in coating of road, 124 hollows on surface of road, 97 road broken up by frost, 124 ■ ruts, Repairs beyond ordinary maintenance, 123 by contract, 158 thick coats and rolling, 104 thick coats and rolling, cost of, 107, 108 r of tools, 134 Reserve of strength, advantage of, 165 Resistance due to gravity, 60 to rolling, 59 Road coating. (See Coating.) labourers. (See Labourers.) level, 134 maintenance, cost of, 143-152 materials, 30-40. (See Materials.) rollers, horse, 21, 107 -, steam, 22, 107-109 surveyor's duties, 153-158 ■ surveyors, accounts to be kept by, 156-158 — , length of road they can superintend, 153 Rollers, horse, 21, 107 , steam, 22, 107-109 Rolling, 21-24 , cost of steam, 107, 108 newly made roads, 21 — , repairs by thick coats and, 104- 109 of, 107-109 Rolling, resistance to, 59 Roman roads, 3 Ruts, repairs of, 98 S. Saint-Etienne, wear of roads at, 89 Sand or gravel bottoming, 15 Scouring of surface, 126 Scraping, 111-116 cost Scraping machines, 111 , hand, 112 Scrapings, composition of, 57 , proportion of, in roads, 57 , removal of, 113 Season for spreading materials, 102 Seat of road, 9, 13 Section, cross, 12 , of Holyhead road, 14 , Telford's, 13 , Walker's, 13 Seine, cost of road repairs in department of, 147 Shouldering, 15 Side channel, 13, 18 ■ , pitched, 19 ditches, 10 , cleaning out, 118, 119, 137 cleaning, 117, 137 Size of road materials, 39 Snow, obstruction from, 127 plough, 127 Sod bordering, 18 , trimming, 117 coping, 2 1 Solid and void, proportion of, in broken stone, 49, 50 Sounding or pitting, 27 South Wales county roacis, 93, 94, 149, 150 — , cost of main- tenance of, 150 on, 150 -, manual labour quantities of materials used on, 93, 94, 150 South Wales Highway Act, 5, 37, 160 Spreading materials, 95-104 , season for, 102 Springs, effects of, on draught, 63 wear, 76 Stacking stone, cost of, 46 Statement of materials delivered and used, 156 Steam rolling, 22, 107-109 Stocking up, 99 ■, cost of, 100 Stone-breaking by hand, 41 by maoliinery, 42 , cost of, 44- 47 Stone-breaking machines, 43 , trials in France, 44 Stone, broken, proportion of solid to void in, 50 , weight of, 51 depots, 21 heaps, 38 , carting from, to road, 39 -, proportions of various sizes of, in road coatings, 54, 55 186 INDEX. Stone, quantities of, broken in a day, 41 , weights of, 50 Subsoil, drainage of, 10 , weight on, 78-81 yielding under loads, 76 Supply of road materials, 37 Surface wear, 72-76 , width of metalled, 18 Surveyors, road, 153 Sweeping, 110 machines. 111 T. Telpokd, 4, 5, 13, 39, 62, 68, 69, 129 Thames BmlDankment, concrete founda- tion on, 17 , cost of repairs on, 144 Thick coats and rolling, repairs by, cost of, 104-109 Thickness, wear measured by, 87 of road coating, 17 . , effect of, 79 Tires, pressure per inch of width of, 65-67 , width of, 65-67, 73, 78-81 Tonnage, traffic measured by, 85-87 Tools, roadmen's, 134 , repairs of, 134 Traction. (^See Draught.) . engines, 67, 80 , repair of damage by, 125 • , cost of, 125 TrafSc, extraordinary, 125 , measurement of, 85-87 Trees, ill-effects of, 83, 119 , lopping, 119 Tresaguet, M., 6 Trestles, use of, 98 Trimming sod bordering, 117 Turnpike roads, cost of repairs of, 148 Turnpike roads, cost of repairs of roads formerly, 148 U. Untbemining of culverts, 126 Vans, Bayley's, 122 Vehicles, weights of, 66, 67 Void and solid, proportion of, in broken stone, 49, 50 Vouchers, payment by, 154 W. Walker's cross-section, 13 Water-carts, 121 , quantities delivered by, 121, 122 Water table, 18 , pitched, 19 Watering, 120-123 , cost of, 122 Wear of roads, 69-84 , effect of detritus on, 90 loads on, 75-80 springs on, 76 width of tires on, 73 from bending and cross-breaking, 69-75 measured by thickness, 87 , measurement of, 87* 88 -, Morin's experiments on, 73-76 , surface, 72-76 Weather, action of, 82 , proportion of wear due to, 69 Weight of broken stone, 50 on subsoil. 78-81 Weights of various stones, 50 vehicles, 66, 67 on wheels, 65-67 Wheeling out materials, 38, 47, 99 Wheels, 64 , breadth of tires of, 65-67 , effects of diameter of, 59, 73 width of, 73 , model,. experiments with, 77-79 , proportion of wear due to, 69 , weights on, 65-67 Whitworth's sweeping machine, 111 Width of metalled surface, 18 tires, 65-67, 73, 78-81 • , pressure per inch of, 65- 67 Work on roads in autumn, 136 spring, 137 summer, 136 winter, 137 connected with materials independent of materials used, 138 used, 138 Working foremen, 133 LONDON: FBTNTBD BY WILLIAM CLOWES AND SONS, LIUITED, STAUFOKD 8TAEET AND CHARING GKOSS. SPONS' TABLES AND MEMORANDA FOR ENGINEERS. Selected and arranged by J. T. Hurst, C.E., Mem. of the Society of Engineers, Mem. Phys. Soc. of London, Surveyor War Depart- ment, Author of 'Architectural Surveyors* Handbook/ 'Hurst's Tredgold's Carpentry,' etc., 64mo, roan, gilt edges, eleventh edition, is. 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A Pocket-Book for Chemists, Chemical Manufacturers, Metallurgists, Dyers, Distillers, Brewers, Sugar Refiners, Photographers, Students, etc., etc. By Thomas Bayley, Assoc. R.C. Sc. Ireland, Ana- lytical and Consulting Chemist and Assayer. Fourth edition, with additions, 437 pp., royal 32mo, roan, gilt edges, t,s. Synopsis of Contents : Atomic Weights and Factors — Useful Data — Chemical Calculations — Rules for Indirect Analysis — Weights and Measures — Thermometers and Barometers — Chemical Physics — Boiling Points, etc. — Solubility of Substances — Methods of Obtaining Specific Gravity— Con- version of Hydrometers — Strength of Solutions by Specific Gravity— Analysis — Gas Analysis — Water Analysis — Qualitative Analysis and Reactions — Volumetric Analysis — Manipulation — Mineralogy — Assaying -~ Alcohol — Beer — Sugar — Miscellaneous Technological matter relating to Potash, Soda, Sulphuric Acid, Chlorine, Tar Products, Petroleum, Milk, Tallow, Photography, Prices, Wages, Appendix, etc., etc. The Mechanician : A Treatise on the Construction and Manipulation of Tools, for the use and instruction of Young Engineers and Scientific Amateurs, comprising the Arts of Blacksmithing and Forg- ing ; the Construction and Manufacture of Hand Tools, and the various Methods of Using and Grinding them ; description of Hand and Machine Processes ; Turning and Screw Cutting. By Cameron Knight, Engineer. Containing 1 147 illustrations, and 397 pages of letter-press. Fourth edition, 4to, cloth, i&f. B 2 CATALOGUE OF SCIENTIFIC BOOKS yust Piihltshedj in Demy Bva, cloth, containing 975 ^ages and 250 lUusiraiions, price •js. 6d. SPONS' HOUSEHOLD MANUAL: A Treasury of Domestic Keceipts and Guide for Home Management. PRINCIPAL CONTENTS. Hints for selecting" a good House, pointing out the essential requirements for a good house as to the Site, Soil, Trees, Aspect, Construction, and General Arrangement ; with instructions for Reducing Echoes, Waterproofing Damp Walls, Curing Damp Cellars. Sanitation.— What should constitute a good Sanitary Arrangement ; Examples (with Illustrations) of Well- and Ill-drained Houses ; How to Test Drains ; Ventilating Pipes, etc. Water Supply-— Care of Cisterns; Sources of Supply; Pipes; Pumps; Purification and Filtration of Water. 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" It is no disparagement to the many excellent publications we refer to, to say that in our opinion this little pocket-book of Hurst's is the very best of them all, without any exception. It would be useless to attempt a recapitulation of the contents, for it appears to contain almost everything that anyone connected with building could require, and, best of all, made up in a compact form for carrying in the pocket, measuring only 5 in. by 3 in., and about i in. thick, in a limp cover. We congratulate the author on the success of his laborious and practically compiled little book, which has received unqualified and deserved praise from every profes- sional person to whom we have shown it." — The Dublin Builder, Tabulated Weights of Angle, Tee, Bulb, Round, Square, and Flat Iron and Steel, and other information for the use of Naval Architects and Shipbuilders. By C. H. Jordan, M.I.N.A. Fourth edition, 32mo, cloth, 2s. 6d. A Complete Set of Contract Documents for a Country Lodge, comprising Drawings, Specifications, Dimensions (for quantities), Abstracts, Bill of Quantities, Form of Tender and Contract, with Notes by J. Leaning, printed in facsimile of the original documents, on single sheets fcap., in paper case, loj. A Practical Treatise on Heat, as applied to the Useful Arts; for the Use of Engineers, Architects, &c. By Thomas Box, IVith 14 plates. Sixth edition, crown 8vo, cloth, 12s. 6d. A Descriptive Treatise on Mathematical Drawing Instruments: their construction, uses, qualities, selection, preservation, and suggestions for improvements, with hints upon Drawing and Colour- ing. By W. F. Stanley, M.R.I. Sixth edition, with numerous illustrations, crown 8vo, cloth, S^- B 2 CATALOGUE OF SCIENTIFIC BOOKS Quantity Surveying. By J. Leaning. With 42 illus- trations. Second edition, revised, crown 8vo, cloth, gs. Contents : A complete Explanation of the London Practice. General Instructions. Order of Taking Off. Modes of Measurement of the various Trades. Use and Waste. Ventilation and Warming. Credits, with various Examples of Treatment. Abbreviations. Squaring the Dimensions. Abstracting, with Examples in illustration of each Trade. Billing. Examples of Preambles to each Trade. Form for a Bill of Quantities. Do. Bill of Credits. Do. Bill for Alternative Estimate. _ Restorations and Repairs, and Form of Bill. Variations before Acceptance of Tender. Errors in a Builder's Estimate. Schedule of Prices. Form of Schedule of Prices. Analysis of Schedule of Prices. Adjustment of Accounts. Form of a Bill of Variations. Remarks on Specifications. Prices and Valuation of Work, with Examples and Remarks upon each Trade. The Law as it affects Quantity Surveyors, with Law Reports. Taking Off after the Old Method. Northern Practice. The General Statement of the Methods recommended by the Manchester Society of Architects for taking Quantities. Examples of Collections. Examples of '* Taking Off" in each Trade. Remarks on the Past and Present Methods of Estimating. Spons Architects' and Builders Price Book, with useful Memoranda. Edited by W. Young, Architect. Crown 8vo, cloth, red edges, y. 6d, Published annually. Seventeenth edition. Now ready. Long-Span Railway Bridges, comprising Investiga- tions of the Comparative Theoretical and Practical Advantages of the various adopted or proposed Type Systems of Construction, with numerous Formulae and Tables giving the weight of Iron or Steel required in Bridges from 300 feet to the limiting Spans ; to which are added similar Investigations and Tables relating to Short-span Railway Bridges. Second and revised edition. By B. Baker, Assoc. Inst. C.E. Plates, crown 8vo, cloth, 5j. Elementary Theory and Calculation of Iron Bridges and Roofs. By August Ritter, Ph.D., Professor at the Polytechnic School at Aix-la-Chapelle. Translated from the third German edition, by H. R. Sankey, Capt. R.E. With 500 illustrations, 8vo, cloth, 15J. The Elementary Principles of Carpentry. By Thomas Tredgold. Revised from the original edition, and partly re-written, by John Thomas Hurst. Contained in 517 pages of'letter- press, and illustrated with 48 plates and 150 wood engravings. Sixth edition, reprinted from the third, crown 8vo, cloth, \2s. 6d. Section I. On the Equality and Distribution of Forces — Section II. Resistance of Timber — Section III. Construction of Floors — Section IV. Construction of Roofs — Sec- tion V, Construction of Domes and Cupolas — Section VI. Construction of Partitions — Section VII. Scaffolds, Staging, and Gantries— Section VIII. Construction of Centres for Bridges— Section IX. Coffer-dams, Shoring, and Strutting — Section X. Wooden Bridges and Viaducts — Section XI. Joints, Straps, and other Fastenings — Section XII. Timber. The Builder's Clerk : a Guide to the Management of a Builder's Business. By Thomas Bales. Fcap. 8vo, cloth, is. 6d. PUBLISHED BY E. & F. N. SPOiST. Practical Gold-Mining : a Comprehensive Treatise on the Origin and Occurrence of Gold-bearing Gravels, Rocks and Ores, and the methods by which the Gold is extracted. By C. G. Warnford Lock, co-Author of ' Gold : its Occurrence and Extraction.' With% plates and 27s engravings in the text, royal 8vo, cloth, 2/. 2s. Hot Water Supply : A Practical Treatise upon the Fitting of Circulating Apparatus in connection with Kitchen Range and other Boilers, to supply Hot Water for Dpmestic and General Purposes. With a Chapter upon Estimating. Ful/y illustrated, crown Svo, cloth, 3J. Hot Water Apparatus : An Elementary Guide for the Fitting and Fixing of Boilers and Apparatus for the Circulation of Hot Water for Heating and for Domestic Supply, and containing a Chapter upon Boilers and Fittings for Steam Cooking. 32 illustrations, fcap. Svo, cloth, ij. 6d, The Use and Misuse, and the Proper and Improper Fixing of a Cooking Range. Illustrated, fcap. Svo, sewed, dd. Iron Roofs : Examples of Design, Description. Illus- trated with 64 Working Drawings of Executed Roofs. By Arthur T. Walmisley, Assoc. Mem. Inst. C.E. Second edition, revised, imp. 4to, half-morocco, 3/. 3J. A History of Electric Telegraphy, to the Year 1837. Chiefly compiled from Original Sources, and hitherto Unpublished Docu- ments, by J. J. Fahie, Mem. Soc. of Tel. Engineers, and of the Inter national Society of Electricians, Paris. Crown Svo, cloth, gj. Spons'' Information for Colonial Engineers. Edited by J. T. Hurst. Demy Svo, sewed. No. I, Ceylon. By Abraham Deane, C.E. zs. 6d. Contents : Introductory Remarks — Natural Productions — Architecture and Engineering — Topo- graphyj Trade, and Natural History — Principal Stations — Weights and Measures, etc., etc. No. 2. Southern Africa, including the Cape Colony, Natal, and the Dutch Republics. By Henry Hall, F.R.G.S., F.R.C.I. With Map. 3s. 6d. Contents : General Description of South Africa — Physical Geography with reference to Engineering Operations — Notes on Labour and Material in Cape Colony — Geological Notes on Rock Formation in South Africa — Engineering Instruments for Use in South Africa — Principal Public Works in Cape Colony: Railways, Mountain Roads and Passes, Harbour Works, Bridges, Gas Works, Irrigation and Water Supply, Lighthouses, Drainage and Sanitary Engineering, Public Buildmgs, Mines — Table of Woods in South Africa — Animals used for Draught Purposes — Statistical Notes — ^Table of Distances — Rates of Carriage, etc. No. 3. India. By F. C. Danvers, Assoc. Inst. C.E. With Map. 4J. 6d. Contents : Physical Geography of India — Building Materials— Roads^Railways— Bridges — Irriga- tion — River Works — Harbours — Lighthouse Buildings — Native Labour — The Principal Trees of India — Money— Weights and Measures — Glossary of Indian Terms, etc. CATALOGUE OF SCIENTIFIC BOOKS Our Factories, Workshops, and Warehouses : their Sanitary and Fire-Resisting Arrangements. By B. H. Thwaite, Assoc. Mem. Inst. C.E. IVi/A 183 wood engravings, crown 8vo, cloth, d. Electricity as a Motive Power. By Count Th. Du MONCEL, Membre de I'lnstitut de France, and Frank Geraldy, Inge- nieur des Fonts et Chaussees. Translated and Edited, with Additions, by C. J. Wharton, Assoc. Soc. Tel. Eng. and Elec. With 113 engravings and diagrams, crown 8vo, cloth, "Js. 6d. Treatise on Valve-Gears, with special consideration of the Link-Motions of Locomotive Engines. By Dr. Gustav Zeuner, Professor of Applied Mechanics at the Confederated Polytechnikum of Zurich. Translated from the Fourth German Edition, by Professor J. F. Klein, Lehigh University, Bethlehem, Pa. Illustrated, Svo, cloth, 12s. 6d. The French- Polisher s Manual. By a French- Pohsher; containing Timber Staining, Washing, Matching, Improving, Painting, Imitations, Directions for Staining, Sizing, Embodying, Smoothing, Spirit Varnishing, French-Polishing, Directions for Re- polishing. Third edition, royal 32mo, sewed, dd. Hops, their Cultivation, Commerce, and Uses in various Countries. By P. L. Simmonds. Crown Svo, cloth, 4J. dd. The Principles of Graphic Statics. By George Sydenham Clarke, Major Royal Engineers. With 112 illustrations. Second edition, 4to, cloth, \2s. dd. PUBLISHED BY E. & F. N. SPON. Dynamo Tenders Hand-Book. By F. B. Badt, late 1st Lieut. Royal Prussian Artillery. With "lo illustrations. Third edition, l8mo, cloth, 4j. 6d, Practical Geometry, Perspective, and Engineering Drawing; a Course of Descriptive Geometry adapted to the Require- ments of the Engineering Draughtsman, including the determination of cast shadows and Isometric Projection, each chapter being followed by numerous examples ; to which are added rules for Shading, Shade-lining, etc., together with practical instructions as to the Lining, Colouring, Printing, and general treatment of Engineering Drawings, with a chapter on drawing Instruments. By George S. Clarke, Capt. R.E. Second edition, with 21 plates. 2 vols., cloth, los. bd. The Elements of Graphic Statics. By Professor Karl Von Ott, translated from the German by G. S. Clarke, Capt. R.E., Instructor in Mechanical Drawing, Royal Indian Engineering College. With 93 illustrations, crown 8vo, cloth, 5j. A Practical Treatise on the Manufacture and Distri- bution of Coal Gas. By WILLIAM Richards. Demy 4to, with numerous wood engravings and 29 plates, cloth, 28^. Synopsis of Contents : Introduction — History of Gas Lighting — Chemistry of Gas Manufacture, by Lewis Thompson, Esq., M.R.C.S. — Coal, with Ajialyses, by J. Paterson, Lewis Tliompson, and G. R. Hislop, Esqrs. — Retorts, Iron and Clay— Retort Setting— Hydraulic Main — Con- densers — Exhausters — Washers and Scrubbers — Purifiers — Purification — History of Gas Holder — Tanks, Brick and Stone, Composite, Concrete, Cast-iron, Compound Annular Wrought-iron — Specifications — Gas Holders — Station IWeter — Governor — Distribution— Mains— Gas Mathematics, or Formulae for the Distribution of Gas, by Lewis Thompson, Esq^.— Services — Consumers' Meters — Regulators — Burners — Fittings — Photometer — Carburizatlon of Gas — Air Gas and Water Gas — Composition of Coal Gas, by Lewis Thompson, Esq.— Analyses of Gas — Influence of Atmospheric Pressure and Temperature on Gas— Residual Products— ^Appendix — Description of Retort Settings, Buildings, etc., etc. The New Formula for Mean Velocity of Discharge of Rivers and Canals. By W. R. Kutter. Translated from articles in the 'Cultur-Ingenieur,' by Lowis D'A. Jackson, Assoc. Inst. C.E. 8vo, cloth, 1 2 J. ()d. The Practical Millwright and Engineers Ready Reckoner; or Tables for finding the diameter and power of cog-wheels, diameter, weight, and power of shafts, diameter and strength of bolts, etc. By Thomas Dixon. Fourth edition, i2mo, cloth, 3^. Tin: Describing the Chief Methods of Mining, Dressing and Smelting it abroad ; with Notes upon Arsenic, Bismuth and Wolfram. By Arthur G. Charleton, Mem. American Inst, of Mining Engineers. With plates, Svo, doth, I2J. dd. CATALOGUE OF SCIENTIFIC BOOKS Perspective, Explained and Illustrated. By G. S. Clarke, Capt. R.E. With illustrations, 8vo, cloth, y. (>d. Practical Hydraulics ; a Series of Rules and Tables for the use of Engineers, etc., etc. By Thomas Box. Ninth edition, numerous plates, post 8vo, cloth, ^s. The Essential Elements of Practical Mechanics; based on the Principle of Work, designed for Engineering Students. By Oliver Byrne, formerly Professor of Mathematics, College for Civil Engineers. Third edition, with 148 wood engravings, post Svo, cloth, 7x. dd. Contents : Chap. I. How Work is Measured by a Unit, botli with and without reference to a Unit of Time — Chap. 2. The Work of Living Agents, the Influence of Friction, and introduces one of the most beautiful Laws of Motion — Chap. 3. The principles expounded in the first and second chapters are applied to the Motion of Bodies — Chap. 4. The Transmission of Work by simple Machines — Chap. 5. Useful Propositions and Rules. Breweries and Mailings : their Arrangement, Con- struction, Machinery, and Plant. By G. Scamell, F.R.I.B.A. Second edition, revised, enlarged, and partly rewritten. By F. Colyer, M.I.C.E., M.I.M.E. With 20 plates, Svo, cloth, 12s. 6d. A Practical Treatise on the Construction of Hori- zontal and Vertical Waterwheels, specially designed for the use of opera- tive mechanics. By William Cullen, Millwright and Engineer. With II plates. Second edition, revised and enlarged, small 4to, cloth, \2s. 6d. A Practical Treatise on Mill-gearing, Wheels, Shafts, Riggers, etc. ; for the use of Engineers. By Thomas Box, Third edition, with 1 1 plates. Crown Svo, cloth, 7^. 6d. Mining Machinery: a Descriptive Treatise on the Machinery, Tools, and other Appliances used in Mining. By G. G. Andre, F.G.S., Assoc. Inst. C.E., Mem. of the Society of Engineers. Royal 4to, uniform with the Author's Treatise on Coal Mining, con- taining 182 plates, accurately drawn to scale, with descriptive text, in 2 vols., cloth, 3/. I2s. Contents : Machinery for Prospecting, Excavating, Hauling, and Hoisting — Ventilation — Pumping — Treatment of Mineral Products, including Gold and Silver, Copper, Tin, and Lead, Iron, Coal, Sulphur, China Clay, Brick Earth, etc. Tables for Setting out Curves for Railways, Canals. Roads, etc., varying from a radius of five chains to three miles. By A. Kennedy and R. W, Hackwood. Illustrated 32mo, cloth, 2s. 6d. PUBLISHED BY E. & F. N. SPON. Practical Electrical Notes and Definitions for the use of Engineering Students and Practical Men. By W. Perren Maycock, Assoc. M. Inst. E.E., Instructor in Electrical Engineering at the Pitlake Institute, Croydon, together with the Rules and Regulations to be observed in Electrical Installation Work. Second edition. Royal 32mo, roan, gilt edges, 4^. (>d. The Draughtsman s Handbook of Plan and Map Drawing; including instructions for the preparation of Engineering, Architectural, and Mechanical Drawings. With numerous illustrations in the text, and 33 plates (15 printed in colours). By G. G. Andre, F.G.S., Assoc. Inst. C.E. 4to, cloth, 9J. Contents : The Drawing Office and its Furnisliings— Geometrical Problems— Lines, Dots, and tlieir Combinations — Colours, Shading, Lettering, Bordering, and North Points — Scales — Plotting — Civil Engineers' and Surveyors' Plans — Map Drawing — Mechanical and Architectural Drawing — Copying and Reducing Trigonometrical Formulae, etc., etc. The B oiler-maker s andiron Ship-builder s Companion, comprising a series of original and carefully calculated tables, of the utmost utility to persons interested in the iron trades. By James Foden, author of ' Mechanical Tables,' etc. Second edition revised, with illustra- tions, crown 8vo, cloth, 5^. Rock Blasting: a Practical Treatise on the means employed in Blasting Rocks for Industrial Purposes. By G. G. Andre, F.G.S., Assoc. Inst. C.E. With 56 illustrations and 12 plates, 8vo, cloth, I Ox. dd. Experimental Science : Elementary, Practical, and Experimental Physics. By Geo. M. Hopkins. Illustrated by 672 engravings. In one large vol., 8vo, cloth, \%s. A Treatise on Ropemahing as practised in public and private Rope-yards, with a Description of the Manufacture, Rules, Tables of Weights, etc., adapted to the Trade, Shipping, Mining, Railways, Builders, etc. By R. Chapman, formerly foreman to Messrs. Huddart and Co., Limehouse, and late Master Ropemaker to H.M. Dockyard, Deptford. Second edition, i2mo, cloth, y. Laxtoiis Builders and Contractors Tables ; for the use of Engineers, Architects, Surveyors, Builders, Land Agents, and others. Bricklayer, containing 22 tables, with nearly 30,000 calculations. 4to, cloth, Sj. Laxtons Builders' and Contractors' Tables. Ex- cavator, Earth, Land, Water, and Gas, containing S3 tables, with nearly 24,000 calculations. 4to, cloth, ^s. CATALOGUE OF SCIENTIFIC BOOKS Egyptian Irrigation. By W. Willcocks, M.I.C.E., Indian Public Works Department, Inspector of Irrigation, Egypt. With Introduction by Lieut.-Col. J. C. Ross, R.E., Inspector-General of Irrigation. With numerous lithographs and wood engravings, royal 8vo, cloth, I/. 16^. Screw Cutting Tables for Engineers and Machinists, giving the values of the different trains of Wheels required to produce Screws of any pitch, calculated by Lord Lindsay, M.P., F.R.S., F.R.A.S., etc. Cloth, oblong, 2s. Screw Cutting Tables, for the use of Mechanical Engineers, showing the proper arrangement of Wheels for cutting the Threads of Screws of any required pitch, with a Table for making the Universal Gas-pipe Threads and Taps. By W. A. Martin, Engineer. Second edition, oblong, cloth, \s., or sewed, dd. A Treatise on a Practical Method of Designing Slide- Valve Gears by Simple Geometrical Construction, based upon the principles enunciated in Euclid's Elements, and comprising the various forms of Plain Slide- Valve and Expansion Gearing ; together with Stephenson's, Gooch's, and Allan's Link-Motions, as applied either to reversing or to variable expansion combinations. By Edward J. Cowling Welch, Memb. Inst. Mechanical Engineers. Crown 8vo, cloth, 6j-. Cleaning and Scouring : a Manual for Dyers, Laun- dresses, and for Domestic Use. By S. Christopher. i8mo, sewed, 6d. A Glossary of Terms used in Coal Mining. By William Stukeley Gresley, Assoc. Mem. Inst. C.E., F.G.S., Member of the North of England Institute of Mining Engineers. Illustrated with numerous woodcuts and diagrams, crown Svo, cloth, ^s. A Pocket-Book for Boiler Makers and Steam Users, comprising a variety of useful information for Employer and Workman, Government Inspectors, Board of Trade Surveyors, Engineers in charge of Works and Slips, Foremen of Manufactories, and the general Steam- using Public. By Maurice John Sexton. Second edition, royal 32mo, roan, gilt edges, S^. Electrolysis : a Practical Treatise on Nickeling, Coppering, Gilding, Silvering, the Refining of Metals, and the treatment of Ores by means of Electricity. By Hippolyte Fontaine, translated from the French by J. A. Berly, C.E., Assoc. S.T.E. IVith engravings. Svo, cloth, gj. PUBLISHED BY E. & F. N. SPON. 13 Barlow s Tables of Squares, Cubes, Square RoolSy Cube Roots, Reciprocals of all Integer Numbers up to 10,000, Post 8vo, cloth, 6^. A Practical Treatise on the Steam Engine, con- taining Plans and . Arrangements of Details for Fixed Steam Engines, with Essays on the Principles involved in Design and Construction. By Arthur Rigg, Engineer, Member of the Society of Engineers and of the Royal Institution of Great Britain. Demy 4to, copiously illustrated with woodcuts and ^6 plates f in one Volume, half-bound morocco, 2I. 2s.; or cheaper edition, cloth, 25J, This work is not, in any sense, an elementary treatise, or history of the steam engine, but is intended to describe examples of Fixed Steam Engines without entering into the wide domain of locomotive or marine practice. To this end illustrations will be given of the most recent arrangements of Horizontal, Vertical, Beam, Pumping, Winding, Portable, Semi- portable, Corliss, Allen, Compound, and other similar Engines, by the most eminent Firms in Great Britain and America. _ The laws relating to the action and precautions to be observed in the construction of the various details, such as Cylinders, Pistons, Piston-rods, Connecting- rods, Cross-heads, Motion- blocks. Eccentrics, Simple, Expansion, Balanced, and Equilibrium Slide-valves, and Valve-gearing will be minutely dealt with. In this connection will be found articles upon the Velocity of Reciprocating Parts and the Mode of Applying the Indicator, Heat and Expansion of Steam Governors, and the like. It is the writer's desire to draw illustrations from every possible source, and give only those rules that present practice deems correct. A Practical Treatise on the Science of Land and Engineering Surveyings Levelling^ Estimating Quantities^ etc., with a general description of the several Instruments required for Surveying, Levelling, Plotting, etc. By H. S. Merrett. Fourth edition, revised by G. W. UsiLL, Assoc. Mem, Inst. C.E. 41 plates^ with illustrations and tables, royal Svo, cloth, \2s, 6d. Principal Contents ; Part I. Introduction and the Principles of Geometry. Part 2. Land Surveying ; com- prising General Observations— The Chain— Offsets Surveying by the Chain only — Surveying Hilly Ground — To Survey an Estate or Parish by the Chain only — Surveying with the Theodolite — Mining and Town Surveying — Railroad Surveying — Mapping — Division and Laying out of Land — Observations on Enclosures— Plane Trigonometry. Part 3. Levelling — Simple and Compound Levelling — The Level Book — Parliamentary Plan and Section — Levelling with a Theodolite — Gradients — Wooden Curves — To Lay out a Railway Curve- Setting out Widths. Part 4. Calculating Quantities generally for Estimates — Cuttings and Embankments — Tunnels— Brickwork — Ironwork — Timber Measuring. Part 5. Description and Use of Instruments in Surveying and Plotting — The Improved Dumpy Level— Troughton's Level — The Prismatic Compass — Proportional Compass — Box Sextant — Vernier — Panta- graph — Merrett's Improved Quadrant — Improved Computation Scale — ^The Diagonal Scale- Straight Edge and Sector. Part 6. Logarithms of Numbers— -Logarithmic Sines and Co-Sines, Tangents and Co-Tangents — Natural Sines and Co-Sines — Tables for Earthwork, for Setting out Curves, and for various Calculations, etc., etc., etc. Mechanical Graphics. A Second Course of Me- chanical Drawing. With Preface by Prof. Perry, B.Sc, F.R.S. Arranged for use in Technical and Science and Art Institutes, Schools and Colleges, by George Halliday, Whitvvorth Scholar. Svo, cloth, 6j-, B 4 14 CATALOGUE OF SCIENTIFIC BOOKS The Assay ers Manual: an Abridged Treatise on the Docimastic Examination of Ores and Furnace and otlier Artificial Products. By Bruno Kerl. Translated by W. T. Brannt. With 65 illustrations, 8vo, cloth, lis. 6d. Dynamo - Electric Machinery : a Text- Book for Students of Electro-Technology. By Silvanus P. Thompson, B.A., D.Sc.,' M.S.T.E. \Neia edition in the press. The Practice of Hand Turning in Wood, Ivory, Shell, etc., with Instructions for Turning such Work in Metal as may be required in the Practice of Turning in Wood, Ivory, etc. ; also an Appendix on Ornamental Turning. (A book for beginners.) By Francis Campin. Third edition, with wood engravings, crown 8vo, cloth, 6j. Contents : On Lathes— Turning Tools— Turning Wood — Drilling — Screw Cutting — Miscellaneous Apparatus and Processes — Turning Particular Forms — Staining — Polishing — Spinning Metals — Materials — Ornamental Turning, etc. Treatise on Watchwork, Past and Present. By the Rev. H. L. Nelthropp, M.A., F.S.A. With 32 illustrations^ crown 8vo, cloth, 6j. 6(^. Contents : Definitions of Words and Terms used in Watchwork — Tools — Time— Historical Sum,- mary — On Calculations of the Numbers for Wheels and Pinions; their Proportional Sizes, Trains, etc. — Of Dial Wheels, or Motion Work — Length of Time of Going without Winding up — The Verge— The Horizontal — The Duplex — The Lever — The Chronometer — Repeating Watches— Keyless^ Watches — The Pendulum, or Spiral Spring — Compensation — Jewelling of Pivot Holes — Clerlcenwell — Fallacies of the Trade — Incapacity of Workmen — How to Choose and Use a Watch, etc. Algebra Self-Taught. By W. P. Higgs, M.A., D.Sc, LL.D., Assoc. InsL C.E., Author of * A Handbook of the Differ- ential Calculus,' etc. Second edition, crown 8vo, cloth, is. td. Contents : Symbols and the Signs of Operation — The Equation and the Unknown Quantity — Positive and Negative Quantities — Multiplication — Involution — Exponents — Negative Expo- nents — Roots, and the Use of Exponents as Logarithms— Logarithms — Tables of Logarithms and Proportionate Parts — Transformation of System of Logarithms — Common Uses of Common Logarithms — Compound Multiplication and the Binomial Theorem — Division, Fractions, and Ratio— Continued Proportion — The Series and the Summation of the Series — Limit of Series — Square and Cube Roots — Equations — List of Formulse, etc. Spons Dictionary of Engineering, Civil, Mechanical, Military, and Naval; with technical terms in French, German, Italian, and Spanish, 3100 pp., and nearly 8000 engravings, in super-royal 8vo, in 8 divisions, 5/. %s. Complete in 3 vols., cloth, 5/. 5^. Bound in a superior manner, half-morocco, top edge gilt, 3 vols., 6/. I2j, PUBLISHED BY E. & F. N. SPON. 15 Notes in Mechanical Engineering. Compiled prin- cipally for the use of the Students attending the Classes on this subject at the City of London College. By Henry Adams, Mem. Inst. M.E., Mem. Inst. C.E., Mem. Soc. of Engineers. Crown 8vo, cloth, 2j. bd. Canoe and Boat Building: a complete Manual for Amateurs, containing plain and comprehensive directions for the con- struction of Canoes, Rowing and Sailing Boats, and Hunting Craft. By W. P. Stephens. With n-umerous illustrations and 24 plates of Working Drawings. Crown 8vo, cloth, i)s. Proceedings of the National Conference of Electricians, Philadelphia, October 8th to 13th, 1884. l8mo, cloth, y. Dynamo - Electricity, its Generation, Application, Transmission, Storage, and Measurement. By G. B. Prescott. With 54S illustrations. 8vo, cloth, l/. \s. Domestic Electricity for Am,ateurs. Translated from the French of E. Hospitalier, Editor of " L'Electricien," by C. J. Wharton, Assoc. Soc. Tel. Eng. Numerous illustrations. Demy 8vo, cloth, 6j. Contents : I. Production of the Electric Current — 2. Electric Bells — 3. Automatic Alarms — 4. Domestic Telephones — 5. Electric Clocks — 6. Electric Lighters — 7. Domestic Electric Lighting — 8. Domestic Application of the Electric Light — 9. Electric Motors— 10. Electrical Locomo- tion — II. Electrotyping, Plating, and Gilding — iz. Electric Recreations — 13. Various appli- cations — Workshop of the Electrician. Wrinkles in Electric Lighting. By Vincent Stephen. With illustrations. iSmo, cloth, 2j. dd. Contents : 1. The Electric Current and its production by Chemical means — 2. Production of Electric Currents by Mechanical means — 3. Dynamo-Electric Machines — 4. Electric Lamps — 5. Lead— 6. Ship Lighting. Foundations and Foundation Walls for all classes of Buildings, Pile Driving, Building Stones and Bricks, Pier and Wall construction. Mortars, Limes, Cements, Concretes, Stuccos, &c. 64 illus. trations. By G. T. Powell and F. Bauman. 8vo, cloth, loj. dd. Manual for Gas Engineering Students. By D. Lee. iSmo, cloth, IX. i6 CATALOGUE OF SCIENTIFIC BOOKS Telephones, their Construction and Management. By F. C. Allsop. Crown 8vo, cloth, <^s. Hydraulic Machinery, Past and Present. A Lecture delivered to the London and Suburban Railway Officials' Association. By H. Adams, Mem. Inst. C.E. Folding plate. 8vo, sewed, \s. Twenty Years with the Indicator. By Thomas Pray, Jun., C.E., M.E., Member of the American Society of Civil Engineers. 2 vols., royal 8vo, cloth, I2j. 6ia?. Annual Statistical Report of the Secretary to the Memiers of the Iron and Steel Association on the Home and Foreign Iron and Steel Industries in \?&<^. Issued June 1890. 8vo, sewed, 5j. Bad Drains., and How to Test them ; with Notes on the Ventilation of Sewers, Drains, and Sanitary Fittings, and the Origin and Transmission of Zymotic Disease. By R. Harris Reeves. Crown 8vo, cloth, 3J-. 6d. Well Sinking. The modern practice of Sinking and Boring Wells, with geological considerations and examples of Wells. By Ernest Spon, Assoc. Mem. Inst. C.E., Mem. Soc. Eng., and of the Franklin Inst., etc. Second edition, revised and enlarged. Crown 8vo, cloth, loj. dd. The Voltaic Accumulator : an Elementary Treatise. By ^MiLE Reynier. Translated by J. A. Berly, Assoc. Inst. E.E. With 62 illustrations, 8vo, cloth, 9J. Ten Years' Experience in Works of Intermittent Downward Filtration. By J. Bailey Dknton, Mem. Inst. C.E. Second edition, with additions. Royal 8vo, cloth, 5^-. Land Surveying on the Meridian and Perpendicular System. By William Penman, C.K 8vo, cloth, 8j-. (>d. The Electromagnet and Electromagnetic Mechanism. By SiLVANUS P. Thompson, D.Sc, F.R.S. 8vo, cloth, 15J. PUBLISHED BY E. & F. N. SPON. 17 Incandescent Wiring Hand-Book. By F. B. Badt, late 1st Lieut. Royal Prussian Artillery. With 41 illustrations and 5 tables. 181110, cloth, 4J. (>d. A Pocket-book for Pharmacists, Medical Prac- titioners, students, etc., etc. {British, Colonial, and American"]. By Thomas Bayley, Assoc. R. Coll. of Science, Consulting Chemist, Analyst, and Assayer, Author of a 'Pocket-book for Chemists,' 'The Assay and Analysis of Iron and Steel, Iron Ores, and Fuel,' etc., etc. Royal 32mo, boards, gilt edges, ds. The Fireman s Guide ; a Handbook on the Care of Boilers. By Teknolog, fdreningen T. I. Stockholm. Translated from the third edition, and revised by Karl P. Dahlstrom, M.E. Second edition. Fcap. 8vo, cloth, 2s. A Treatise on Modern Steam Engines and Boilers, including Land Locomotive, and Marine Engines and Boilers, for the use of Students. By Frederick Colyer, M. Inst. C.E., Mem. Inst. M.E. With 2,(> plates. 4to, cloth, 12s. 6d. Contents : I. Introduction — 2. Original Engines — 3. Boilers — 4. High-Pressure Beam Engines— 5. Cornish Beam Engines— 6. Horizontal Engines— 7. Oscillating Engines— 8. Vertical High- Pressure Engines — 9. Special Engines — 10. Portable Engines — 11. Locomotive Engines— 13. Marine Engines. Steam Engine Management; a Treatise on the Working and Management of Steam Boilers. By F. Colyer, M. Inst. C.E., Mem. Inst. M.E. i8mo, cloth, 2j. A Text-Book of Tanning, embracing the Preparation of aU kinds of Leather. By Harry R. Proctor, F.C.S., of Low Lights Tanneries. With illustrations. Crown 8vo, cloth, ioj. 60?. Aid Book to Engineering Enterprise. By Ewing Matheson, M. Inst. C.E. The Inception of Public Works, Parlia- mentary Procedure for Railways, Concessions for Foreign Works, and means of Providing Money, the Points which determine Success or Failure, Contract and Purchase, Commerce in Coal, Iron, and Steel, &c. Second edition, revised and enlarged, 8vo, cloth, 2/x. 1 8 CATALOGUE OF SCIENTIFIC BOOKS Pumps, Historically, Theoretically, and Practifally Considered. By P. R. Bjorling. With 156 illustrations. Crown 8vo, cloth, Is. 6d. 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Losses in Gold Amalgamation. With Notes on the Concentration of Gold and Silver Ores. With six plates. By W. McDermott and P. W. Duffield. 8vo, cloth, 5j. A Guide for the Electric Testing of Telegraph Cables. By Col. V. HosKiCER, Royal Danish Engineers. Third edition, crown 8vo, cloth, 4J. ()d. The Hydraulic Gold Miners Manual. By T. S. G. Kirkpatrick, M.A. Oxon. With 6 plates. Crown 8vo, cloth, 6s. " We venture to think that this work will become a text-book on the important subject of which it treats. Until comparatively recently hydraulic mines were neglected. This was scarcely to be surprised at, seeinjj that their working in California was brought to an abrupt termination by the action of- the farmers on the debris question, whilst their working in other parts of the world had not been attended with the anticipated success." — The Mining World and Engineering Record. The Arithmetic of Electricity. By T. O'Conor Sloane. Crown 8vo, cloth, 4^. dd. PUBLISHED BY E. & F. N. 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Well Sinking. 28 CATALOGUE OF SCIENTIFIC BOOKS. JUST PUBLISHED. In demy 8vo, cloth, 600 pages, and 1420 Illustrations, 6s. SPONS' MECHANICS' OWN BOOK; A MANUAL FOR HANDICRAFTSMEN AND AMATEURS. Contents. 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