1 rl, I ..' * IGHTNING CONDUCTORS \.!f --^ '^m MEDO- M.InstC,E, Cotnell XHniversit^ OF THE mew IPorft State College of agriculture ^.Afeen the Conductors must be made mechanically as well as electrically (L.R.C. Rule 7), that is, two pieces of cable or tape sweated together might test well when new, but in the course of ten years be found not to be in electrical contact. A simple mechanical joint can be made by using a box, as shown by Fig. 13. This can be used for plain, two-way, up to four-way joints. For a T joint the previously tinned cable is partially opened and the loose end inserted at A^, as shown by Figs. 14 and 15, if a simple joint is required, the two ends are twisted together, in both examples the cable is laid in the previously heated box and molten solder or pot metal com- pletes the electrical connection. Somewhat similar connecting boxes are used for tape. Fig. 16 shows the plan of a box making a (S?!:: Jil "^ A. Fig. 13- Fig. 14. fe s # .Fig. 15. JOINTS. 25 ta= u o ron m m Fig. 1 6. T joint. If it is required to connect the cable or tape to a single air terminal, such as are used on chimneys and other points, the conductor is inserted in the lower part of the socket, Fig. 17, and the rod in the top end, and molten solder is poured in to complete the joint. This method of forming a permanent joint is also used for the air terminals or elevation rods. The multiple points are not screwed into a ball, through which the rod passes, as the author has found that the thread deteriorates with age and the points (even the whole top) has been known to fall off. It will be seen by reference to Fig. 8, that the points are secured to the centre point, which is a prolongation of the actual rod, by means of the sleeve, Fig. 18 {in this figure four points are shown, the centre one being omitted), which has pockets or recesses in which the points are firmly secured, and the box is filled up with solder ; the f)oints are at first kept close together, as shown by Fig. 19, for convenience of transport. An aigrette is made up in a similar manner. Referring to the elevation Fig. 11, the pockets are shown at B D, in which the previously tinned ends of the rods 1-2-3 3-re placed, they are also shown in plan- by Fig. 20, and end view Fig. 21 ; the centre point is inserted in the cable, which is partly untwisted. One advantage possessed by this method of securing the various points to the cable or tape is, that all the joints are made by pouring into the boxes or sockets, the hot pot metal or solder which has been previously melted, so that it is unnecessary to have a " devil " or fire on the roof of the building, as it is Fig. 17. — Connector, Cable to Rod. Fig. 18. — Sleeve. Fig. 19. 26 MODERN LIGHTNING CONDUCTORS. Fig. 20. Fig. 21. quite easy to quickly hoist the pot of solder, which is enclosed in some receptacle, by means of a pulley to any height required. Connecting Metal Worki — It would not always be practicable to connect the actual down conductors with all the ironwork or to the rain-water gutters, rain-water pipes and ventilating pipes, so pieces of solid copper wire of, say. No. lo B.W.G., or two or three strands of the actual copper rope can be used, and be either soldered or clamped to the above. An efficient plan is to use a metal socket, which is sweated to the copper cable, and is fastened to the object by means of a bolt which passes through an eye formed on the opposite end to the socket. Pipes can be connected by means of a clamp, but care must always be taken to prevent galvanic action between the metals which are joined together, and as this action is greatly hastened by damp, the connections must never be in a position where water will collect. Fig. 22 is an end view of the hollow clamp B^, round the pipe F^. Lead is poured through the hole C^, and before it is solidified the clamp is tightened by the screws G-. In some cases the cable or tape can be twisted round the pipe, and be soldered to it, but it is difficult to obtain a good electrical .joint. The Down Conductors are run to earth. The most important factor in, the system is the "earth connection," which is described at page -3^1 ; and for greater security it is advisable to inter- connect these conductors, either at a short distance above the ground level or by a buried rod or tape, with each other, and all the rain-water and other pipes, as these having been previously joined together above, will also act as conductors. If the arrangements described have been intelligently carried out the building will be enclosed in a framework of metal, which ought to be sufficient to convey a flash of lightning to the ground without damaging the structure, and at the same Fig. THE BIRD-CAGE SYSTEM OF IRON CONDUCTORS. 27 time there will be sufficient points for the discharge of the electricity which gathers on the building during a storm, and these will thus help to neutralise the intensity of the stroke. To more nearly apprqach the " cage '' mentioned in the L.R.C. Report,* copper would be an expensive material for this system of protection, it also is not so suitable as iron. IRON CONDUCTORS. The use of iron as a material instead of copper has been advocated from time to time since the days of Franklin, but it was left to Sir Oliver Lodge to demonstrate the advantages it possesses, and show that a conductor of moderately high resistance, such as iron wire, would get rid of the store of energy contained in a flash in a slower and therefore quieter manner than the ordinary copper tape or cable. t The material most suited for this purpose is soft galvanised (or terned) iron. If made up (with strands of seven ply) about f-inch diameter, it is large enough for ordinary buildings in positions where it can be easily renewed, but for church towers and other inac- cessible places a much larger diameter is preferable. The method Fig. 23. of running is similar to that already described, only, having a cheaper material, one can use more of it, and more nearly approach the ideal " bird-cage,'' of Clerk Maxwell, Fig. 23. a, d show the iron wires or rods on roof and sides of the building, h, h are the spikes * See page 7. t See Introduction — Lodge, p. iii. 28 MODERN LIGHTNING CONDUCTORS. Fig. 24. with which the conductor is armoured ; if economy is an object, elevation rods need not be used. In actual practice the number of rods here shown are not required ; for instance, in an ordinary building there would be the horizontal conductor on the ridge, with connections to the guttering, the rain-water pipes forming the down conductors. No air terminals are really necessary as the vertical cable may be carried up so as to project above the various chimney stacks, pinnacles or points, and can be opened out so as to present a number of separated wires. The horizonta! conductor can be armoured by twisting round it short pieces of steel wire, the two lower legs keeping the con- ductor a little distance away from the roof The author has designed a special device suitable for use in almost all positions with iron wire, Fig. 24. It is a small triangular malleable iron casting furnished with a spike, when used with a horizontal conductor the two lower legs can be bent to grip the ridge of the roof, or it can be fastened to a lead flat. The same casting without the spike can be used with vertical rods instead of the holdfast. Fig. 12. As shown by Fig. 25, the cable is being held away from a wall. A simple and efficient method of joining the casting to the cable is accomplished by means of a specially designed ferrule of lead, which is inserted and closed up by a punch ; and a somewhat similar joint can be used wherever the system has to be inter- connected, and if any particular conductor has to be removed the ferrule can be easily abstracted. In actual practice the wires which form the cage over the building will hardly be noticed from the ground level, the number of barbs on the horizontal wire can be modified ; in fact, where there are many pinnacles or chimneys, as each would have its own rod, a few points on the horizontal wire would be all that is necessary. A number of down conductors which may be run with stranded iron wire, as shown by Fig. 24, will descend from the Fig. 25. METHODS OF PROTECTION. 29 horizontal rod until they meet the guttering, and if this is not provided all round the building, the gap must be filled with an iron conductor, which can be supported by the same triangular casting. The whole of the pipes in the building should be connected to the system in the manner previously described by means of the guttering at the roof, and again by a solid iron wire near the ground, and as the rain-water pipes are also used as conductors, it is advantageous to bond or inter-connect their joints. There are many ways of doing this ; the most practical method would be to have a special lug cast on the socket and spigot, to which con- nection could be made ; however, as the rain-water pipes are often already fixed, the arrangement shown by Fig. 26 can be used. The actual contact is made by lead plugs, which are contained in the two elbows which are pressed against the pipe by means of the clamp. Factory Chimneys. — It will be seen by reference to the Reports, Nos. 28 and 57, that chimneys have been struck although fitted with lightning rods. The L.R.C. Rule 4 suggests that " the rods above the band might with advantage be curved into an arch provided with three or four points." This method, which is very general on the Continent, is to be recommended, and the use of iron rods is an economy over the ordinary copper coronal. It is, however, necessary to keep the arch well away from the top of the stack, so that the metal is not over-heated. Fig. 27 gives details of the arrangement in use on the chimney of the Consolidated Engineering Company's works at Slough. It is always advisable to have two down conductors, and if iron is used for these, rod is preferable to stranded wire, especial care being taken with the joints. The two down conductors should be connected to the coronal on opposite sides of the shaft, and extend from same down opposite sides to a point about 4 feet above the ground line, at which height a similar conductor should be fitted round the shaft, and inter-connected. All metal bands round chimneys should be con- nected to the conductor. The conductors should be kept away from the brickwork, as L.R.C. Rule 10. Molten zinc should be used for soldering iron conductors ; where these are solid the P'iG. 26. 30 MODERN LIGHTNING CONDUCTORS. surface of the joint need not necessarily exceed that of the cross section of the conduc- tors. The joint should be put together pre- viously by screws or rivets, and the soldered joint, especially if used in underground work, should be carefully pro- tected from local elec- trical action by tarred rope. Stranded iron con- ductors can be connected (as previously described) by use of a box joint ; the box, Fig. 28, must be of the same metal as the conductors. Vanes.— Particular attention must be paid to the necessity of making a permanent joint to the spindle. A clamp is prepared of the same material as the spindle, and is furnished with two bolts to tighten ; if iron is used it is well to line the clamp with a piece of sheet lead. The conductor is sweated into a socket which is fitted with an eye, through which one of the tighten- ing bolts passes. In the FK!. 27 TERMINALS IN FORM OF AN ARCH FOR CHIMNEY STACK. I'lG. 28. EARTH CONNECTIONS. 31 case of the vanes of churches and those fixed in inaccessible positions, two separate clamps should be used. Internal Masses of Metal. — Roof trusses fitted with longitudinal iron tie rods will, as a rule, be found to be electrically connected, but should this not be the case each truss must be joined to the conductors. All large and long masses of metal, such as beams, girders, roof trusses, tie rods, hot water systems, traveller ways, hoisting crabs, engines, boilers, large machines, and ventilators fixed in the interiors of buildings, should be connected to all con- ductors that pass near them, and as far as possible with one another. The discontinuous parts of traveller rails should be connected by straps, or in some cases tramway bonds might be used. If electric light wires are run in tubes, such as the " SIMPLEX," this should be earthed. Metallic contact between lead or zinc sheeting and flashings should be carefully studied, and for special work strips of sufficient size should be either burnt on to lead or soldered in such a way that the joint will stand rough usage, and allow for expansion or contraction. Earth Connection. — " It is essential that the lower extremity of the conductor be buried in permanently damp soil ; hence proximity to rain-water pipes, and to drains, is desirable. It is a very good plan to make the conductor bifurcate close below the surface of the ground, and adopt two of the following methods for securing the escape of the lightning into the earth. A strip of copper tape may be led from the bottom of the rod to the nearest gas or water main — not merely to a lead pipe — and be soldered to it ; or a tape may be soldered to a sheet of copper 3 feet by 3 feet and -^ inch thick, buj'ied in permanently wet earth, and surrounded by cinders or coke ; or many yards of the tape may be laid in a trench filled with coke, taking care that the surfaces of copper are, as in the previous cases, not less than 18 square feet. Where iron is used for the rod, a galvanised iron plate of similar dimensions should be employed. " The use of cinders or coke appears to be questionable owing to the chemical or electrolytic effect on copper or iron. Charcoal or pulverised carbon (such as ends of arc-light rods) is better. A tubular earth consisting of a perforated steel spike driven tightly into moist ground and lengthened up to the surface, the conductor reaching to the bottom and being packed with granulated charcoal, gives as much effective area as a plate of larger surface, and can easily be kept moist by connecting it to the nearest rain-water pipe. The resistance of a tubular earth on this plan should be very low and practically constant." — Lightning Research Committee, i^o£. 32 MODERN LIGHTNING CONDUCTORS. The methods (printed in italics) here repeated, suggested by the Lightning Rod Conference, still hold good, but great attention must be given to the connection between the conductor and the earth plate ; soldering alone is not sufficient, but a mechanical joint is also necessary. Fig. 29 shows a method designed by the author. The arrange- ment for connecting to water-pipes has already been described at page 26, and illustrated by Fig. 22. Tubular Earth.— It is well known that the most important matter for attention is the earth connection, and it is misleading, if the present method of burying an earth-plate is employed, to suppose that, even if the conductor has been led into ground which is moist at the time, that after a lapse of years it will still make good electrical connection with the earth, as sometimes the Fig. 29.— PLAN AND SECTION OF EARTH plate Is found not to be in electrical PLATE SHOWING CONNECTION TO COntaCt COPPER CABLE. The lightning conductors at St. Paul's were discovered by the author in some instances actually insulated from the earth, although they were not very old, as they had been taken into a conduit which was subsequently drained (Fig. 30). To guard against a recurrence of this danger, which is always possible where earth-plates are ^ ^_^ buried a few feet / L^^,v-^.v.^v^v^^-^.^f^^■v^^^^^^-^.v^svvv^J~^^ under the ground, which maybe moist at the time but loses all electrical conductivity by drainage opera- tions, the tubular earth has been substituted, as shown in the following illustration (Fig. 31). This is made in two sizes, and consists of a strong perforated steel pipe, either \\ inches or 2 inches diameter, and furnished Fig. 30. — SECTION of old conduit, showing EARTHENWARE DRAIN, IN WHICH THE CONDUCTORS WERE FOUND. TUBULAR EARTH 33 with a sharp spike, which will cut its way through chalk or gravel. At St. Paul's Cathedral it was easily driven through the broken stone which marks the site of the previous structure, destroyed by lightning long before Benjamin Franklin's discovery of the lightning rod. The end of the tube having been protected by a thick driving-piece, (Fig 32), which is screwed on temporarily, it is easily sunk by means of a hammer or mallet, and if there is an obstruction the pipe is moved by a bar inserted in the holes of the driving-piece. Lengths, con- nected by a special form of socket, are added until moist ground is reached. The conductor is threaded through the cast-iron top piece, and dropped to the bottom of the tube, which is filled with finely- granulated charcoal. An electrical joint between the conductor and the cast-iron top is now made by pouring lead or pot-metal into the socket through which the con- ductor passes, and tamping it in the same way as if it were the joint of a water-pipe. The earth connection is now complete ; but, in order to make it permanent, and to keep the moistness which is essential, a small piece of pipe is led from the special hole in the casting either to the nearest rain-water pipe, as shown in Figs. 31 and 33, or, if this is not available, the pipe is allowed to project above the ground, so that water can be occasionally poured down. The cast-iron cap is, last of all, inserted on the top of the tube, and serves to mark the position of the lightning conductor ; a useful precaution, as conductors are often cut by workmen who have no idea of their existence. Deep holes Fig. 33. "^^"^ the foundations of a building are avoided with this system of tubular earth ; it also has the advantage of being some- what cheaper than other forms of equipment. C2 34 MODERN LIGHTNING CONDUCTORS. 4 The number of earths depends on the ground area of the building; there cannot be too many, and it is advisable to divide them up as much as possible. For instance, at St. Paul's Cathedral, Fig. 34, although the connection to the water main on one side and to the Hydraulic Power Company's pipes on the other gave almost perfect earths, others, both of tube and plate form, were sunk at the various points marked by the O. The network of conductors on the roofs is also shown, the position of the aigrettes being marked by the small o. TESTING. This may be considered under two heads : — A, the Conductor itself, B, the Earth Connection. If the main conductors are made of continuous lengths of stranded wire or tape, joints need only occur where the horizontal conductors meet the main conductors, and this should not be if 4 possible in inaccessible places, anyhow the I joints should be good mechanically as well "^ as electrically, so that they will last as long as the conductors. ^ A. — The electrical testing of the whole circuit becomes more difficult as we approach the cage formation. A careful r//////"^ visual inspection will show if any joints are loose or parts dis- placed, and it is quite possible to insert test clamps so that a portion of the system can be isolated, but these without they are inspected from time to time may give trouble. B. — The earth connection can easily be tested by pro- viding a test clamp in some place near the ground, where it cannot be interfered with, and where earth plates are used it is advisable to examine and test them annually. With the tubular earth this is unnecessary, a blow with a mallet will show if the tube has become loose in the ground, and as long as the contact is good, the electrical Fig. 33 METHODS OF PROTECTION. 35 resistance will be unaltered, providing always that there is sufficient charcoal to fill the tube and that it is kept moist. In very dry weather or in countries where no rainfall takes place for a considerable time o 2 % O in o oo oo oo oo oo oo 36 MODERN LIGHTNING CONDUCTORS. water should be poured down the tube by a pipe, which can be attached in any convenient position. Elaborate testing is unnecessary, but occasional testing in ordinary weather is no real security as to what may happen after a long continued drought. Sir Oliver Lodge suggests the following simple plan : — " Two earths should be provided quite independent of each other (one a water main for instance, the other a ton of coke), and they should be connected first to each other, and then to the conductor by a copper band. Now let the band connecting the two earths pass through some covered out- house, and have a well overlapping junction of two flat areas pressed together by a spring, but capable of being raised on or off each other by pulling at a handle or a rope. A Galvanometer indicator and Leclanchfe cell permanently connected so as to send a current between the two earths directly the handle is raised, will show by its deflection the state of conductivity of the two earths. The Galvanometer and Wheatstone Bridge and Ohm's law and conductivity are simply not in it, and can no more point out what path lightning will take than a trickle down a hill-side will fix the path of an avalanche." The Admiralty suggest the case of an ammeter with divisions, each of which represents 0"02 amperes ; two accumulator cells connected . in series are joined through the instrument to the two earth connections under test, the current being sent first in one direction and then in the opposite. If the observed steady current is 2 amperes or more then the earth is in good condition. Examination of a building after a lightning STROKE. — It is not a very easy matter to definitely fix the course of a flash, especially if the damage is slight. A careful observer will trace out its path by signs on the brickwork, and often by pieces having been chipped out of rain-water leads and sockets of pipes. A faulty earth is easily recognised by the upheaval of the ground where the conductor enters. The author has found some of the external metallic work partially magnetised after a building has been struck, and it would be very interesting if a number of observations were made. The Lightning Research Committee issued the following to their observers to aid them in making their reports : — " I. Any signs or indications of where the flash appears to have first struck, and an account of the damage done. " 2. A specification and drawing of the metal-work of the building,, paying special attention to metal of every kind which comes anywhere in the METHODS OF PROTECTION. 37 neighbourhood of the conductor, whether roof guttering, lead covering, rain- water spouts, sewer ventilators, telephone wires, bell-wires, gas-pipes, ornamental railings, &c., &c., carefully ascertaining whether any of these were either purposely or accidentally connected with the lightning conductor, and, if not, what their nearest distance was from it. " In the drawing, all metals may be indicated in red, no matter of what kind they may be ; the hypothetical path of the lightning, as appears to the observer most probable, may be sketched in blue, remembering that bifurcation of path is not unlikely. Places of damage may be indicated by a blue swelling or patch, the size of the patch giving a rough idea of the relative damage, and an arrow being employed, when necessary, to call attention to any small patches liable to be overlooked. The patches may be numbered, and the nature of the damage at each place stated in the description. Any place where fire broke out is to be specially attended to. " 3. The nature and condition of the conductor, especially with reference to its continuity, its earth, and its elevation ; also how fixed, and, if carried horizontally, its length as compared with the vertical height of its terminal above the ground ; also note whether it made any sharp curves or loops round projections of the building, or took an indirect course. Cases of damage where there have been more than one or several conductors are specially important. " In the case of church steeples the wind vane should receive special attention, and the mode in which its rod terminates in the steeple should be ascertained. " In the case of chimneys, any internal metal flue should be carefully specified. Likewise any indication that the flash took the column of hot air in preference to the conductor should be recorded ; also whether the conductor was bent or curved over the mouth of the chimney or not. " In any case of importance the earth of the conductor should be specially examined, being, if possible, dug down to for this purpose ; and a complete specification of the nature of the earth, the nature of the soil, and of any metal ramifications as well as of moisture in its neighbourhood, should be made. " Any signs that the discharge has entered the earth should be recorded ; and if the conductor is at any point damaged or otherwise affected, this should be specified, and, when interesting, a sample of the damaged portion should be sent. If the conductor has recently been examined and tested, or otherwise reported on, the fact should be stated." 38 CHAPTER V. CONSIDERATIONS AS TO COST AND SPECIFICATIONS. LHE following extract from Sir Oliver Lodge's preface* to the Lightning Research Committee's Report, aptly defines this question. " The amount of protection to be allotted to any building is no doubt analagous to the question of insurance generally ; that is to say, the amount of premium it is desired to pay may be compared with capital at stake and the risk run ; and this is doubtless a matter for individuals and public bodies to consider for themselves." The author's conclusion is that there is very little advantage in what might be termed " unit lightning rods." For instance, in London one sees isolated rods on certain of the chimney stacks of the many Board Schools, it is true that if these particular chimneys were struck, the damage to the building would be greatly lessened, but why should they be selected, while the metal work about the roof, also the other stacks, are left unprotected ? If a building has a high tower — or a church, take for instance, with a spire — it would be extremely foolish not to provide one or two conductors running from the highest point to earth ; but this gives no security to the nave, and if any other part of the structure happens to be in the path of a discharge from a cloud to the ground the stroke may disregard the protected tower or spire and fall on the building, choosing some lower point. The question then is not the erection of a rod or rods, but of the amount of money to be spent on the entire system. Usually the question of the maintenance of a building is of sufficient importance that it is proposed to spend annually a certain sum of money to keep it in good repair ; this amount would be increased by so little to keep a well designed system of lightning conductors in order that the *' See Page iii. STEEL FRAME BUILDINGS. 39 amount is hardly worth consideration, so that the only point to examine is that of first cost. Storms are dissipated by the smoke from a collection of chimneys such as are found in large towns, and the numerous overhead wires have doubtless a shielding effect ; it is therefore not so necessary to fix lightning conductors on buildings in cities as on those in the suburbs, which are more liable to be struck. All prominent buildings, such as churches, banks, and any having a high dome or tower, should be protected wherever they are. This remark especially applies to public buildings and to museums, art galleries, hospitals, prisons, government and municipal offices. It seems anomalous that large sums of money should be spent on the protection from fire of our national collections of art treasures, while the question of possible damage by lightning is simply ignored. All flagstaffs should have a conductor with a point fixed above the cap and run directly to earth, also a connection to all the metallic supports of the rod. Note that certain localities are especially in the path of storms, and that a building once struck is liable to be again damaged, so that special care should be taken in protecting it. Farm houses and barns and windmills are frequently struck, also small residential buildings which are so numerous in the outskirts of towns. The question of expense deters many owners from considering the matter, but by using iron wire, a rough-and-ready system of lightning rods could be easily installed which would be quite as effective as the present costly arrangements. STEEL FRAME BUILDINGS. " No cases of damage to modern steel frame structures have come under the notice of the Committee. The ordinary method of construction, how- ever, in this country does not provide full protection. In many cases the steel columns stand on stone foundations, and the metal is not carried deep enough for effective earthing. The metal columns ought to be earthed at the time of construction." Extract from the L.R.C. Report. The American system of construction provides in itself the "cage protection" which has been described, and if care is taken to join up electrically the metal work of the roof with the frame, and also see that this is well connected to earth, not in one or two places 40 MODERN LIGHTNING CONDUCTORS. only, but in such a manner that a flash may be quickly dissipated no supplementry conductors are required. Fig. 35 is taken from a photograph of a building under con- struction. The author recommended the placing of aigrettes (Fig. 8) at intervals on the roofs, and joining these by cable conductors to Fig. 35. the metal principals below, iron rods were also fixed to the columns above the concrete foundations and inter-connected with earths sunk into moist ground. SPECIFICATIONS IN DETAIL. The following are from actual Specifications by the Author for various kinds of buildings. No. I.— Modified Cage Protection, Copper and Iron Cable. Fig. 36 shows the new building of the Royal Horticultural Society, Westminster, E. Stubbs, R.I.B.A., Architect. It consists of a front as shown, also a large hall at the back, with an arched roof, mainly glazed, supported by iron girders ; the roof is carried partly by the brick walls and partly by iron columns. The whole of the rain-water pipes are part of the system, as well as the special conductors. The tubular earths on the front side are shown. CONSIDERATIONS AS TO COST AND SPECIFICATIONS. 41 Rochester Street Side. One conductor of seven J-inch strands galvanised iron w^ire, will run along, as shown in plan, near spring of arches on two sides of the hall, starting from two of the iron uprights nearest the earths, this conductor will, at four places, descend to earth close to the discharge Fig. 36. of the rain-water pipes. The conductor running horizontally will be con- nected to the base of each of the vertical girders by being fastened to them with galvanised iron cleats, which will be secured by two f-inch screws. The cable will therefore be inter-connected to all the metal work before running to' the two earths at each side of the hall. At the top of roof provide and fix three 4-point copper standard pattern aigrettes, Fig. 11. Connect each to ridge of ironwork by two J-inch galvanised iron screws, a piece of lead being placed under the iron base of each casting, and lead washers under heads of screws, which must be a tight fit to prevent water getting into the screw holes of the casting. Frontage to Vincent Square. A f-inch 7-ply stranded copper conductor should be run along the ridge of the roof, being kept away about 3 inches from same and held by a form of holdfasts, which are fitted with specially designed 42 MODERN LIGHTNING CONDUCTORS. pieces of flat copper of Q-shape, so that they can be sprung round the ridge tiles. This conductor will be taken up the four chimney- stacks, being kept away from the brick work by holdfasts (Fig. 12), and Will be connected at each chimney, by a box joint, to a J-inch solid copper air terminal fitted with three points ; the conductor will also be joined by means of box joints (Fig. 28), without cutting same, to branches leading up the two gables, and by continuing same to top of the four lead-case fleches, and with single point elevation rods on the top of these. This conductor will be connected at the back to two of the earths which serve for the opposite side of the roof. Care will have to be taken when making these connections of copper cable to iron by means of box joints, that no galvanic action is set up, and the boxes should be of galvanised cast iron, the galvanised conductor being connected to the outside of the box, whilst the copper is sweated, by molten pot metal, to the inside of the box. In the front the two down conductors will descend by the roof to earth as shown — always kept away from the wall by holdfasts — then down the front in a position where they will be least noticed, until they arrive near, but not touching, the rain-water down pipes ; they will then be led from the front wall underground to two tubular earths, which will be auto- matically kept moist as described. These earths will be connected to the bottom of the rain-water pipes, and similarly all guttering and rain-water pipes will be connected to the conductors, the latter at the rain-water heads. All the ventilating and other pipes will be connected to the system near the gutters and inter-connected about 2 feet from the ground by a galvanised iron wire. Earths. These, six in number, will be on the tubular system, and each consists of a i J-inches wrot iron tube, furnished at its lower end with a perforated steel point.* This tube will be driven absolutely vertically at least 8 feet below the lowest excavation, if any, or the lowest foundation of the building. If the ground is soft the tube must be sunk until it hardly moves with a full blow of a sledge hammer. At surface level an extension piece of cast iron is attached, fitted with a movable cap, on which is cast " Lightning Conductor," which is to be flush with the ground. The cable in each case runs into a socket of this cast-iron piece, and then to bottom of the tube, which is filled with * Instructions for driving, and for removing an obstacle if met with, are sent out by the patentees' licensed makers. SPECIFICATIONS. 43 granulated carbon and gently rammed. Electrical connection is made between the cable in the socket by pouring in lead, which is tamped, so that the cable is held firmly in the centre of the socket. A piece of |-inch gas pipe is inserted in the cast-iron piece, and led to the nearest rain-water pipe, so that it looks up the inside of same ; it is covered with a small cap of woven wire to exclude dirt. Conditions of Tender. The Contractors to supply the whole of the materials required, and execute the work to the entire satisfaction of the Consulting Engineer. The Contractors to supply all ladders, scaffold, or any tools necessary for the work, and to be solely responsible for any compensation to workmen under the Employers' Liability Act. All materials to be submitted to the Consulting Engineer before erection, and, if so required, an electrical test to be made in his presence. A ground plan, on which the position of conductors and of earths is shown, accompanies this Specification. No. 2.— SPECIFICATION FOR THE PROTECTION OF A CHURCH— COPPER CONDUCTORS. A building of ordinary design, with spire of masonry, on a tower ; the nave and lower part forming the chancel have slate roofs. The Spire and Tower. — The vane spindle is connected by means of a band of same material, shaped so as to spring on and make a good fit. If of copper, the band may be strip, if inches by \ inch, secured by one J-inch and one f-inch copper bolts and nuts, the conductor to be, if only one is used, of seven strands, J-inch outside diameter cable (if two conductors are run down opposite sides of the spire each can be ^-inch diameter), to be fixed to the band by a strong copper socket, which is to be sweated to the cable, and also secured by two set screws, the eye at the other end of the socket to be firmly held by the f -inch bolt, the band being formed to receive the flat end of the socket. The cable will be kept at intervals, say, of ID feet, away from the stone work by holdfasts (Fig. 12) ; if there is a rain-water pipe near the base the cable should run to earth near this pipe, and the conductors must be kept clear of the coping by a holdfast on the tower, and be led at a very wide angle to clear same ; a subsidiary cable, say, of seven strands, |-inch diameter, should be connected to any metal work or flashings on the tower, and if there are pinnacles, this should go right round outside, and a solid copper 44 MODERN LIGHTNING CONDUCTORS. J-inch diameter rod be run so as to project, say, 6 inches, clear above each pinnacle, and be jointed to the cable by a box joint without cutting. See page 24. The Nave. — A horizontal J-inch cable will be run on holdfasts, at least 3 inches clear of the ridge, joined to the conductor descending from the tower (the number of holdfasts to be sufficient to prevent sagging) ; the cable on ridge will descend at the extreme end (first over the chancel, if it is lower) to earth ; at intervals, say, between alternate windows, f-inch stranded down conductors will be led down slope of roof over guttering to earth on each side (this cable can be stopped at the rain-water heads if expense is an object), it is to be connected, if passing close to rain-water heads, by cutting a strand and sweating the two ends to a socket and eye-bolt as previously described, and if the distance exceeds one foot, then a piece of :J-inch copper wire must be used. It is similarly to be connected to the guttering, which must also be in contact with the rain-water heads. Note. — The joints of rain-water pipes should be bonded, especially if of loose fit, or filled in with an insulating cement. On arriving at lowest point, if this is in a dry area, run a J-inch solid copper wire on gun-metal eyes right round the building, about 2 feet from ground, and connect this to all the down conductors, water pipes (not gas pipes), and other pipes or metal flues of every description, by means of box joints, or by carefully twisting several turns of ^-inch copper wire and soldering at each connection. Another method is to bury the J-inch solid copper and similarly connect — in which case a notice should be put on the walls to avoid accidental interference. EarthSi — The number of these will depend on the ground area of the building, but should never be less than four ; the down copper cables must be run to the earths in as direct a manner as possible without joints. If plate earths are used the cable must be mechanically fixed (see Fig. 29) and sweated. With this description of earth a disconnecting clamp for testing (of approved pattern) should be pro- vided at or near the wall, at such a height that it cannot be interfered with. With tubular earths that are kept moist automatically these clamps are not of importance. PLATE earths should be dug up after they have been fixed about a year, to see that the copper is in good contact with the charcoal ; tubular earths can have a little more of the material SPECIFIC A TIONS. 45 inserted from time to time if on removal of the cap it is not visible in the cast-iron extension piece. Aigrettes (see page 22) should be fixed on the horizontal conductors at distances of about 30 feet apart, all crosses, points or finials of every description should have a single point conductor, and any stove pipes should be connected above and below to the upper and lower conductors. Note. — The motion work and movement of clocks should be connected to the system, also the framework of the bells, should this be metallic. If the spire is covered with metal, at least two separate con- ductors should descend to earth; and in this case they may be laid in contact with the sheathing, and be fastened by straps instead of holdfasts. Iron staircases or hand-rails in towers should be connected at top and bottom to the conductor. Fig. 37. also all lead roofs and flashings, iron framework of windows and stove. The rules of the L.R.C. should be embodied in the Speci- fication. No. 3.— IRON CONDUCTORS. The following is a Specification of the conductors on a detached residence at Hove. Fig. 2,7. A horizontal |-inch diameter cable of 7 strands iron wire is run across the ridge, but kept away by specia' 46 MODERN LIGHTNING CONDUCTORS. holdfasts, to which it is secured, and rests on the top of the iron cresting ; at each chimney stack a similar cable rises to i foot above the pots, and is opened out to form spikes, the joints being made by a lead ferrule, as shown in Fig. 24 ; the conductors descend to ground on two sides of the house, being held away from the walls by holdfasts. Fig. 25. On the roof it connects on two sides to the gutters, and at the points shown by the finials on the cresting four similar conductors descend the roof, and are also connected to the gutters. The gutters are con- nected to the rain-water heads by special clamps, care to be taken to prevent electrical action at the joints. The ventilating pipes are also connected to the system, and in the area a No. 10 gauge galvanised iron wire is run all round the structure through eyes which are driven into the wall ; this wire passes round all pipes and is soldered to the two f-inch cable lightning rods. The bottom of all the rain-water pipes is also joined by cable to the conductors, as shown. The " Simplex " tubes containing the electric light wires are to be earthed, also the gas service, as L.R.C. Suggestion 8. EARTHS. — These are of the tubular form, and are two in number, fixed as described at page 33. The cost of all the work, exclusive of the two earths, one on each side of the house, was about £\o. FARM BUILDINGS. A general idea of what is necessary can be obtained from the foregoing description, but should there be no guttering, it would be necessary to run a small cable, or even a solid wire, round the eaves, and connect the horizontal conductor to this by similar cables or wires down the roofs. Good earth may often be attained by leading the conductors into a brook or well, but several yards should be coiled up in the latter case or spread along the bed of the stream in the former. Note. — Copper should not be placed in any well or small stream used for drinking purposes. A more complete protection would be arrived at by more closely imitating the cage shown by Fig. 23, that is, the building would be enclosed by a greater number of horizontal and vertical iron wires. In the case of factories where inflammable materials are used, such as celluloid, or where fireworks are manufactured, the extra expense would be justified by the greater security. MODIFIED CAGE PROTECTION WITH IRON WIRE. 47 MAGAZINES USED FOR EXPLOSIVES. The L.R.C. in their Report, page 413, say: — " For structures intended for the manufacture or storage of gunpowder or other explosives the adoption of the bird-cage protection would be justified alone on the score of public safety. The method of erecting single lightning rods would not afford sufficient protection." The way to make such a building perfectly safe is to completely enclose it in iron, the floors may be lined with wood or other soft material to prevent ignition of stray powder by persons walking on the iron. Such a building, according to Lord Kelvin, " would be perfectly safe, the need for the earth is absolutely done away with if the magazine is completely enclosed in metal." These views are confirmed by the report of H. M. Inspectors of explosives for the year 1900, who comment on the two accidents in the factories of the Nobel Explosives Company at Krummel and Hamm, Germany. 48 CHAPTER VI. NOTES ON AMERICAN AND CONTINENTAL PRACTICE. ,HE "lightning-rod man" is well known to all settlers out West, and his pertinacity in introducing business has made the profession a synonym for " smartness." As a rule the protection afforded by the travelling expert is very small, and when the author was engaged in railway engineering in the United States he often found that the two iron rods fixed to the sides of a farmhouse had a very indifferent earth connection and were simply driven a short distance into the ground. A better method is now often adopted, a round iron rod about J inch in diameter extends from the ridge of the metal roof about 4 feet above the top of each of the chimney stacks, its lower end being connected to a piece of iron in the form of a saddle which is soldered to the metal roof, to this also is joined the top of each rain pipe by means of the guttering. The rain-water pipes are connected by an iron strap to the earth, which is made by driving a pipe into the ground until it reaches moist earth ; the upper end of the pipe is left about 6 inches below the surface, thus it can be watered artificially or by the rain. To assist the collection of moisture, a larger sleeve is sometimes placed outside furnished with a perforated top and set flush with the gutter. With slate or wooden roofs, it is recommended that bands of tin plate or galvanised iron are inserted under the slate covering on the rafters of the roof, being connected at the top with the " air terminal " conductors, and below with the gutters and rain- water pipes as previously described ; in the case of a mansard roof the sheet metal or flashing is also connected to the system. It is stated that if all the connections are properly made, so as to secure good electrical connection between themselves, the rain-water pipes, and the earth, there is no liability whatever of the woodwork or other material about the roof being set on fire or damaged, or any person beneath the roof being injured by the electricitj- in a NOTES ON AMERICAN PRACTICE. 49 lightning discharge while passing through the combination on its way to earth. In a more recent visit it was found that greater attention had been paid to the question of protection, a special form, somewhat similar to that used by the L.R.C., having been prepared by the Weather Bureau of the United States Department of Agriculture and largely circulated. During the year 1898 reports were received from 1,866 cases of buildings being damaged or destroyed, directly or indirectly, by lightning, the damage to buildings and their contents being $1,441,880, but only a small proportion of these were fitted with lightning rods. There was an immense amount of damage to live stock. In one State, Iowa, 266 head were killed in 1898, and of these 1 1 8 were found in close contact with wire fences, which were not protected by ground wires. The report stated : " Unquestionably, wire fences as now constructed serve as death traps, causing a vast amount of loss every year ; there were evidences that the lightning struck the fence at a considerable distance from the point where the stock was killed." A large number of people are struck by lightning every year while either hanging or removing clothes from the wire ropes, which are much used instead of the ordinary clothes line. In 1902, the opinion seems to be gaining ground that the methods adopted in the past required improvement, and that owing to the very inefficient protection which had been afforded by the con- tractors who had installed lightning rods on many public and private buildings, lightning rods were dropping out of architects' specifica- tions, so that few new buildings were protected at all ; they were often struck, but as the insurance policy covered the loss, little notice was taken, although deaths occurred either by direct stroke or from chimneys or masonry falling. The author was informed that the then present conditions were thought to be unsatisfactory, and that architects and engineers generally would like to be advised as to what protection they should adopt. That large amount of damage by fire caused by lightning did take place, was shown by the reports of the Fire Com- missioners of many cities. The action of lightning when striking those high steel buildings known as sky-scrapers is peculiar, and is worth investigation, as examination does not show in what direction the current flows to earth. In many cases in New York the buildings are insulated from the ground by the fact that the foundations are blasted 50 MODERN LIGHTNING CONDUCTORS. out of the rock on which the city is built ; however, they appear to be lightning-proof. The subject is further considered in the report of the stroke at Boston which is illustrated and described at page 82. Latest Practice Abroad. GERMANY. Much attention to the subject of a better method of protection has been given. In 1901 a sub-committee of the Berlin Elektro- Technical Association was formed, consisting of Messrs. Aron, Feussner, Findeisen, Naglo, Neesen, Nippoldt, Strecker and Leonard Weber. The following is an extract of their recommendations : — " I. The lightning receivers should consist of vertical points. The points of towers or gables, edges of the ridge of the roof, tops of chimney stacks, and other high parts of buildings, should be converted into receivers, or be provided with suitable receivers. The conductors should be in metallic connection with the receivers and the earth ; they should go round the build- ing, the roof especially, and if possible on all sides, and then be led from the receivers to the ground by the most direct route, avoiding as much as possible all sharp curves. The earth connections should consist of metallic conductors connected to the lower conductors on the building, and should descend into the ground and extend as far as possible, preferably where the earth is damp. " 2. The metallic parts of the building, and masses of metal in and upon it — especially those in contact with the earth and offering large surfaces (such as pipes) — should be connected together as much as possible, and to the conductor also. Special receivers and conductors are rendered unnecessary if these metallic parts of the building comply with the requirements mentioned in paragraphs i, 4, and 5. Both for perfecting the system and for decreasing cost, the question of utilising the pipes as conductors should be considered when erecting new buildings, making use also as much as possible of all the metallic parts of the building for protective purposes. " 3. The protection afforded by a conductor is the greater the more perfectly all the prominent portions of the building are protected by receivers, the larger the number of receivers and conductors, and the more extended the connections to earth. Generally speaking, damage by lightning is dimin- ished if all the metallic parts of buildings of considerable extent are inter- connected, especially if the highest parts are connected to earth, even if these connections are not made specially with a view to protection from lightning. " 4. Inter-connected conductors of iron should not have a section of less than 50 square millimetres, unconnected ones not less than 100 square NOTES ON CONTINENTAL PRACTICE. 51 millimetres. If of copper, half the section is sufficient ; zinc must be one and a half, and lead three times the section for iron. Conductors must be securely fixed to resist strong winds. " 5. The connections of and to the conductors must be made strong, be of good electrical contact, and with as large a surface as possible. Unwelded and unsoldered connections should have metallic surfaces of contact of not less than 10 square centimetres. " 6. The lightning conductor system should be repeatedly tested ; and when alterations are made in the building, the necessity of alterations in the system of lightning conductors should be considered." Baurat Findeisen, of Stuttgart, deduces from certain statistics as to strokes by lightning in Wiirtemberg that there is some doubt as to the efficacy of intercepting rods in attracting and protecting against lightning, and that there is no point in measuring the resistance of lightning conductors, since the high pressure of lightning would over- come even high degrees of resistance. It would be sufficient, he thinks, if all the protecting sheet metal on the roof-ridge and elsewhere were connected with the gutters and rain-water pipes — if the chimney, which is so often struck, were protected by a rope of galvanised iron wire, projecting to a height of one-half to one metre above the chimney, and joined as conductor with the protecting metal, and if the water pipes were used as earth connections, they also having a strong wire rope running along them, which, at the lower end, should be untwisted and carried in fan shape about half a metre down into the ground. Four such earth connections at the corners of the build- ing to be protected would, he considers, suffice. If yet further pre- cautions are desired, galvanised sheet iron might be substituted for this. Lightning conductors of this type, Herr Findeisen states, have proved their efficiency. In his book entitled " Rathschlage u.d. Blitzschutz '' (Berlin Springer), he describes very cheap methods of protection. On page 229 he states : — " The main point is to guard against fire ; it is of more importance to reduce the ;^2oo,ooo which Germany loses every year through lightning to a minimum by simple precautions, than to bring it down to nothing in individual cases by a disproportionally large expenditure." He evidently prefers more elaborate installations, as the conduc- tors now being fitted to the new Town Hall at Stuttgart in accordance with his specification are to cost not less than ;^200, a sum not much less than the ;^25o expended on the protection of the Hotel de Ville at Brussels. 52 MODERN LIGHTNING CONDUCTORS. German practice has been for a long time in advance of what we have been accustomed to here. The rules referred to are only the elaboration of a system which has almost universally been adopted for the protection of public buildings in Germany. For instance, at Cologne Cathedral the work is very carefully executed, and of a design which might be followed with safety. Stranded copper cables are used, and these invariably run through galvanised iron stanchions with flat feet, by which they are bolted to the stonework. To avoid galvanic action setting up between the iron and copper, the eyes of these supports are bushed with lead. They keep the conductor about 7 inches away from the structure, or sufficient to enable the cable to be stretched tight and not run round projections in the manner we are accustomed to see here. For this purpose there are tightening screws at several points. A somewhat similar arrange- ment is used for the horizontal conductors which run each side of the roof, being kept well away from it. The terminals of the lightning rods are almost always plain spikes without branches, but a building has many of these, both on the highest portions and along either the tops of the walls or ridge of roof, the whole being connected together by the horizontal conductor, which is usually run in the method described. A timber shed near Frankfort has these vertical rods about 15 feet apart, and a circular petroleum storage tank at intervals all round the top. Many local boards in Prussia insist upon lightning conductors being fitted on public buildings, such as schools, town halls, hospitals, and churches. The regulations vary with the different local authorities. In Frankfort the Municipality have the following : " The erection, alteration, and repairs of lightning conductors must be in accordance with the scientific rules now in force. The conductors must be of pure copper, and of not more than seven strands. House owners must have their lightning conductors examined at least every two years, and an examination is also required in the cace of the erection of, or alterations or repairs to, a lightning conductor which has been struck. Designs and specifications of proposed erections must be sub- mitted to the local board, and for the accuracy of the same the house owner is responsible." HOLLAND. The following is translated from the Dutch of the very complete and valuable report made by Dr. D. van Gulik at the request of the Dutch Academy of Science, which has recently been published under NOTES ON CONTINENTAL PRACTICE. 53 the title of " Further Inquiries in regard to the Protection of Buildings from Lightning" (Haarlem, 1905): — " I. Lightning conductors serve to lessen the risk of fire and of serious damage for the buildings protected by them, and to reduce considerably the danger to life for those who inhabit the buildings. Whether the risk of a building being struck by lightning is also lessened by the installation of points or bundles of points is very doubtful. Where, therefore, economy is an object these may be first dispensed with. "2. In protecting buildings from lightning we must bear in mind that, contrary to what we notice in ihe case of constant electric currents — " {a) Lightning shows a great tendency to distribute itself over such conductors as may be present, and in so doing pays little heed to the electrical resistance of the conductor. '• [b) That it finds no great difficulty in making its way, often for a considerable distance, through the air or through any other good conducting medium. '• {c) That it prefers to move, as far as possible, in a straight line, and that, therefore, sharp turns or spiral windings in conductors present hindrances which, in view of the properties mentioned in paragraphs (a) and {b), readily lead to lateral discharges. " Absolute security is not attainable, or attainable only with great difficulty, and in any case at considerable expense. On the other hand a quite satis- factory degree of protection can be secured by very simple means. ''3. The greater the importance attached to the preservation of a building and its contents, the more perfect can the system of conductors be made, and thus a higher coefficient of safety is obtained by increased expenditure. " 4. The conductors at present used in Holland secure a fairly high degree of safety in the case of houses with tiled or slated roofs, as they reduce the risk of fire when struck to an average of between one-sixth or one-seventh. Statistics show, however, that the lightning frequently diverges from them, and may even strike the buildings without touching the terminal rods. Moreover, the cost of installation is so great that many people are deterred thereby from having these useful appliances fitted. Certain general improvements and simplifications may, however, be pointed out, by means of which the conductors would, even at a lower cost, better answer the purpose for which they are intended. "5. The improvements are in the main as follows : — " (a) All salient positions Uable to be struck should be provided with terminals in the form of short rods or wires, and the roof should be girt round on all sides by wire conductors. This would take the place of the high terminal rods with their imaginary cone of safety. " {b) Several conductors running to the earth should be fitted. " (c) The system of conductors should be connected with any extensive metaUic mass present in the building, if necessary at more points than one. In the case of gas and water pipes such connection is absolutely necessary. 54 MODERN LIGHTNING CONDUCTORS. " 6. The principal simplifications may be summed up thus : — " (a) High terminal rods should be abolished, as it is difficult to fix them firmly enough. " (b) Copper, which is the material generally used for conductors and earth connections, should be replaced by iron. This, if well galvanised, will resist atmospheric influences for a very long time, and can, moreover, be easily protected by a coat of paint. " ic) The thickness of the conductors should be reduced. In support of this we may adduce the evidence of the ordinary telegraph wire, which is seldom, if ever, found to be melted except at the point where it is struck. Even in providing for extreme cases we should not lose sight of the fact that a wire will do its duty even though it succumbs to the force of the stroke. " {d) The metallic constructional portions of the building should be pressed into service as conductors. By this means either the conducting system is extended, with a consequent increase in the margin of safety, or the use of special conductors may be partly dispensed with. This last expedient provides a ready means, in the case of special classes of buildings, of providing quite efficient conductors at a trifling cost. It is not necessary that there should be metallic contact between the metal constructions provided that they overlap one another over an area of lo square centimetres. "7. In making earth-connections too much importance is often attached to reaching the ground water level, while on the other hand too little care is taken to secure a good connection between the conductor and the uppermost layer of soil. By paying attention to this a considerable saving may in some cases be made in the cost of the earth-contact. In isolated cases where connection with underground pipes, &c., is possible, no special earth connection is necessary. " 8. When building houses it is desirable that the conductors should always be marked on the plans. This makes their installation easier and reduces the cost. Moreover, it enables architects to exclude from their plans constructions which would tend to increase the risk of fire in the event of the house being struck by lightning. " 9. Special precautions are necessary in the case of thatched roofs. These consist mainly in keeping the conductors some distance away from the roof and in making the wire of such thickness that it shall not be destroyed at the point where it is struck by lightning. If this be done, a high degree of safety is attainable even in the case of thatched roofs.'' HUNGARY. Through the good offices of the Rector of the Royal Joseph Polytechnical University, Budapest, Dr. Moritz von Hoor kindly favoured the Lightning Research Committee in 1904 with the follow- ing remarks concerning the precautions against lightning then coming NOTES ON CONTINENTAL PRACTICE. 55 into use in Hungary, showing the method of their installation, and their efficacy as proved by experience : — " Up to the year 1892, in Hungary as well as in other countries, lightning conductors with collecting points according to the Franklin system were the only ones in use. Here, as elsewhere, the view was universally accepted that absolute security for the efficiency of lightning conductors was afforded by the largest possible cross section of the lightning rod by a slight change of the collecting apparatus, and by a good earth connection. It was held, therefore, that a conductor had been rightly set up when the collecting point and the earth had been connected by strong copper wires or cables, and care had been taken for a good earth contact. " Experience of such lightning conductors, however, as well as obser- vations systematically taken in England and the English colonies, and in Germany, proved that lightning rods on this principle did not answer their purpose, and in particular that the directions as to the area of protection of the conductor and the relation between height and base of the protected zone were of no practical value and quite baseless. " It was repeatedly observed that there were lateral discharges from the conductor in the direction of the metal parts (badly connected apparently with the earth), that sparks leapt over curves in the conducting apparatus, and in general that buildings and other objects protected by the collecting points suffered damage from lightning, though to a far less extent, as shown by statistics, than objects altogether unprovided with lightning conductors. "It was not until the beginning of the nineties that our views as to the function and the correct installation of lightning conductors became more clear, as a result of the investigations then made into electric oscillations, and of the right appreciation of the self-induction of lightning conductors. " Following up the work of Hertz and Lodge, I was the first in our country to treat this question theoretically and experimentally in a scientific manner on the basis of the new principles, and was the first here to suggest the abandonment of the conductors with collecting points, and the intro- duction of contour conductors without collecting points, similar to Faraday's parrot cage. "Leopold Stark, chief engineer of Messrs. Ganz & Co., has since made an exhaustive study of this question, and has worked out various practical plans for cage conductors, with a special view to their application to the protection of agricultural objects peculiarly exposed to risk from lightning (cf Villdmhdritbk kiilonos toMntettel mezogazdasdgi epitletekre, irta : Stark Lip6t gdpeszmernok, Budapest, Fovarosi Nyomda, 1903). " For some years now, as a result of these works and of the agitation started by the above-mentioned scientists, cage lightning conductors of this kind have been largely in use with us, both on town buildings and on agricultural objects. They consist, as Sir Oliver Lodge, and, long before him, Faraday suggested, of barbed wire, or strong iron wire, or sheet iron 56 MODERN LIGHTNING CONDUCTORS. bands, which, following the contours of the roof and building or other objects, conduct to separate earth connections or to connections joined underground by a circular conducting wire. " The cost of such conductors is with us hardly more than that of the conductors with gilt collecting points and copper conducting wires, and they have been found admirably efficacious, as might have been deduced from theoretical reasoning ; so that the military authorities both in Austria and Hungary have had all magazines of explosives protected in this manner. " Special care is taken, in setting up these cage conductors, to avoid the sharp curves arising from a sudden change in the direction of the earth conductors, so as to reduce as far as possible the self-induction of the earth connection. " Importance is likewise attached to good earths, but experience shows that if the cage arrangement is well carried out and the number of cage wires not too scanty, even without a very good earth connection the conductor still works satisfactorily. " At present both the cage and the Franklin collecting point system are in use with us ; but of late years, especially for agricultural objects, the cage system is coming more and more in vogue, and probably in a short time all the new conductors will be of this kind." BELGIUM. The Hotel de ViUe at Brussels has been often quoted as the most perfectly and elaborately protected building in the world; hovi^ever, it was struck in 1888 and set on fire, not because the conductors failed to carry off the stroke which fell on the building, but owing to the neglect or oversight of leaving a horizontal bar of metal totally unconnected with anything. This bar according to Sir Oliver Lodge did not even receive a side flash, yet the induced surgings set up on it were so violent as to ignite some gas and cause a small fire. The Melsen system, which is largely adopted in Belgium, con- sists of a network of metal rods connected together at the top and furnished with an aigrette or bundle of eight 4 mm. copper rods spread out like a feather, so that the terminal points project so little above the horizontal conductor which runs along the roof that they can hardly be seen from below, but yet break up the area of the building so as to leave little space unprotected. Copper is used for the conductors, but where they descend, a special iron box is employed, in which they are embedded in zinc, and from this the down rods can be con- tinued in iron and also connected to the rain-water pipes and other NOTES ON CONTINENTAL PRACTICE. 57 ironwork of the building. The provision for earth connection is very ample, for instance, in the case of the Hotel de Ville there are 24 iron rods t inch in diameter ; of these eight are fastened to the spigot of an iron pipe 2 feet in diameter, which is suspended in a well in the courtyard, another third is connected with one of the principal iron mains of the water supply of the town, and the remaining series are taken in a similar way to a large iron gas-main. FRANCE. The Melsen system has been used to a certain extent for the protection of the public buildings in Paris, but French architects seem to prefer the long single point, probably because it is more easily adapted to the elaborate weather vanes and finials which are so largely used, presumably for the embellishment of buildings of importance. The standard rod or tige (Fig. 38), is 6 metres high, the diameter at base about 0"o6 metre, tapering to nothing at the point ; the rod is firmly con- nected to the woodwork of the roof, and the copper or iron conductor is fixed at the base by means of a shackle. The conductor is usually kept away from the building by means of supports, and is very carefully led into moist earth, or, in the case where the foundation is of rock, connected to a network of wires which run for a very con- siderable distance under the surface, with the idea of obtaining as large an area as possible. Where a well can be used, the earth connection is prepared by plaiting up galvanised iron strips so as to form a basket (Fig. 39), which contains a sort of grapnel which is attached to the conductor, the basket being filled with coke and lowered into the water. Horizontal conductors are always fixed on the roofs ; the old method was to support an iron bar by means of stanchions, which were either screwed into the timbering or fastened by means of a flat plate. The stranded cable which has now taken the place of the solid rod is similarly held, and in both cases all the vertical Fig. 39. rods are thus inter-connected. Fig. 38. 58 MODERN LIGHTNING CONDUCTORS. ITALY. Great attention has been paid to questions of protection, and nearly all the public buildings have had the older systems rearranged- The author recently visited St. Peter's Cathedral, Rome, and found that the method adopted is not unlike that which he specified for the very similar, though smaller, edifice of St. Paul's. Following the usual Continental practice, well-painted iron rods about ^-inch diameter are run vertically at approximately equal distances round the building, and these conductors are kept away from the structure by distance pieces of marble, which are let into the stone- work at the galleries. Conductors are run horizontally in a similar manner all round, and united to the Fig. 40— The Vatican-. various vertical rods ; the dome is also protected, and the conductors are united to the small group attached to the cross, which stands at a height of 435 feet above the pavement. According to the theory of an area of protection, it would not have been necessary to protect the area immediately below, but the Italian authorities have wisely discarded the fallacious idea, and have encircled the structure by an iron network, which at various salient points is connected to high air terminals, each stayed by four guys. The position of the earths, which are formed in wells distributed at intervals round the building, is marked on marble slabs let into the walls. The adjoining NOTES ON CONTINENTAL PRACTICE. 59 Vatican buildings, (Fig. 40) are also excellently protected — the high air terminals are built into stone-work projections evidently intended for ventilation, the system of iron conductors is clamped to the base of these vertical rods and is continued over the roofs, being kept away from the tiles by resting on marble supports, and at the end of each ridge an air terminal is arranged to project over the side of the roofs at an angle of about 60 degrees. The use of iron rod enables the protection of this the largest palace in the world to be Fig. 41. effectually shielded, at a cost which although large is trifling' compared with copper. The quantity of material required for encircling the roof can be realised when one understands that the palace now covers an area of about thirteen and a half acres, of which about six are occupied by the twenty courts. Fig. 41 is a sketch of the roof of a hospital at Naples, and illustrates the way the conductors are run over the building ; the system is connected to the adjoining wing by a small wire which crosses the intervening space. 60 CHAPTER VII. EXAMPLES OF LIGHTNING STROKE ON PROTECTED AND UNPROTECTED BUILDINGS FROM THE LIGHTNING RESEARCH COMMITTEE'S OBSERVER REPORTS. ,HE following are selected from observers' reports on buildings furnished with lightning conductors that were struck between the years 1901 and 1904. For the complete list see Appendix A, which also gives an analysis of each case, and the name of the observer. No. 25. Alexandra Hotel, Darwen, July 21st, 1901. — The chimney which was struck is marked by a X (Fig. 42). The three lightning conductors of J-inch rope are shown. Formerly there = were conductors on all the chim- neys. These should be replaced. YiG, 42. *N0TE. — If originally all had been interconnected by rods on the roofs and to the rain-water pipes the conductors would have taken the discharge. No. 2. Kea Church, near Truro, March ist, 1901. — Fig. 43. The portion of the stroke which fell on the vane was received by the conductor. The copper roofing of the spire was charged with a current probably of very high potential, as the lightning descended the rain-water pipe until it came opposite some lead flashing L, where it again divided, a portion going to earth by another rain-water pipe, N, while the rest passed along a small copper wire used for fixing plants (which was 9 inches away from the pipe), at E, back *N0TES BY THE AUTHOR, EXAMPLES OF LIGHTNING STROKE ON PROTECTED 61 BUILDINGS. to the conductor and to earth, some of the copper from the wire which was fused being deposited on the copper tape. A woman who was in the church scrubbing the font, received an induced electric shock which knoclced her down ; she was probably touching a large metal ewer which stood on the ground. Note. — The single lightning conductor (which was of modern design and in good order), attached to the vane 120 feet above ground, was not sufificient to carry off the induced charge from the roof. If all the rain- water pipes had been properly earthed and connected to the copper sheeting, the various alternative paths would have averted the damage. The path is indicated by the 000 circles and by the line H E. No. 28. Chimney at Shire Oak Brewery, Walsall, 20 feet high, standing 567 feet above sea level, July 22nd, 1901. — A conductor of copper tape fitted with multiple points on the elevation rod was fixed to the stack, which was 4 feet 6 inches square at top. The lightning struck the opposite side, and, after displacing the head, descended by the conductor, which it tore from its fastenings, heating a portion almost to fusion. Those in the neighbourhood were said to have received electric shocks. Note. — It is not safe to depend on one conductor, especially if it simply terminates in a point and not in the manner recommended by the L.R.C., page 17. No. 30. Army Convalescent Hospital, Golder's Green, July 25th, 1901. — Lightning struck the vane 2 (Fig. 44), which was about i foot 6 inches lower than point of conductors and about 20 feet distant. Note. — The necessity of connecting all the ironwork as per Suggestions 2 and 5 of the L.R.C. Fig. 43. 62 MODERN LIGHTNING CONDUCTORS. (e9Kj0to% t yL. (/I CciiJucJcr cilxul t^ aivvt /ud*e-i~ l^'a&oui ^ ti/uui^iM Lai^.nJetAscl.iii^^KjoS^- Fig. 44. No. 54. Stoerhead Lighthouse, Scotland.— The flash struck the tower, but instead of following the lightning con- ductor a portion of the discharge passed by the brass speaking- tube X (Fig. 45), and divided at the point where the tube crosses the telephone wires, one part going direct to earth by the wires, the other part by the head bar of the iron bedstead and thence again into the wires, both finding earth at the "^ "S'-cr-otat.^ Fig. 45. same pole. A hole about a foot in diameter was blown out of the brick wall near the bedstead, B ; the earth wire of the telephone was melted. Note. — This is a repetition of No. 56, and somewhat similar to No. 2, and shows that another conductor should have been run from the dome, also, that the iron railing should have had an independent earth. EXAMPLES OF LIGHTNING STROKE ON PROTECTED 63 BUILDINGS. No. 56. Devaap Lighthouse, Scotland, December 8th, 1 90 1. — The Hghtning conductor of |-inch round copper rod was fitted to the gun-metal bracket of the ventilators ; it had two conical platinum points, one of which was slightly fused, the other being blunted down for \ inch as if cut off. The two earth plates were each 20 inches by 10 inches by \\ inches, and were buried 8 feet from rail of towers. The current took a secondary course by the lead whistle-pipe for 30 feet, where it reached the dwelling house, damaged roofs, and descended by lead down pipe to some underground water tanks, blowing off their covers. Note. — A single conductor will not carry off a B flash, especially if there is a copper dome as on the above. The whistle-pipe should have been properly earthed. No. 57. Chimney Stack, Strickiands Brewery, Rochdale, December, 1901. — The high chimney was struck during a heavy hailstorm ; the air terminal of three points was found hanging over the top. The rod was continuous, but where it passed the base of the stack, it was insulated from an iron strengthening band, leaving a space between the insulator and band of half an inch. The chimney was cracked in much the same way as Fig. 46, the bottom of the fault Fig. 46. being near the roof of an adjacent shed. The stack had to be taken down. Note.— Instead of being insulated the rod should have been connected to the iron band ; it would have been advisable to have run a second G4 MODERN LIGHTNING CONDUCTORS. conductor on the opposite side of the stack, but at any rate the band should have been independently connected to earth. See page 17. Fig. 47. — Plan of Roof. Nu. 64. Cavendish Laboratory, Cambridge, July, 1902 (Fig. 47). — A conductor off-inch rope was fixed to the tower and went to earth at E ; the main stroke followed the con- ductor, but a side flash struck the hip knob A, about 40 feet away, and made its way to the lead cheek of the dormitory, and at its lowest point B earthed by following a small compo gas pipe (which was laid just below the sill), which it pierced on its way. Note. — The conductor was fixed on the old idea that because it was on the tower it protected the roof, whereas the hip knob should have had a separate earth connection. If the gas had not been turned off at the main, the building would probably have been set on fire. No. 65. All Saints' Church, IViaidenhead. — A lightning rod of |-inch round iron projected 6 feet above the top of the spire, and was continued to the iron tie in spire, thence a i-inch copper rope ran to the ground (Fig. 48). The cock was knocked off spindle and fell; spire damaged; a hole 18 inches deep made where con- ductor entered ground ; brickwork at foot of tower chipped ; no rain. Note. — It was incorrect to use the support of the finial as a conductor, which should have been taken up outside the spire and there connected to the iron rod. This is an example of a conductor, evidently having an im- perfect earth, acting sufficiently well to prevent serious damage to the building. EXAMPLES OF LIGHTNING STROKE ON PROTECTED 65 BUILDINGS. No. 66. St. Andrew's Church, Marks Tey, June 7th, 1902 (Fig. 49). — The weather-cock, to which the copper rope was attached, was displaced, and earth much disturbed, and gully broken at X ; the rod took the discharge. Note. — The stroke {not a very severe one) was mitigated by the heavy rain. Had a B flash occurred there would have been Fig. 48. more to report. The displacement of "the weather-cock was probably due to faulty connection between the con- ductor and the spindle of vane. The badly-arranged earth connection is to be condemned. No. 67. Near Heathfleld, Sussex. — This house, which had lightning rods fixed on every chimney, was struck in June, and again in August, 1902. The latter stroke is an example of a divided B flash, part of which fell on a chimney stack, bending the rod Fig. 49. as shown on Fig. 50. A small unprotected statue about 40 feet 66 MODERN LIGHTNING CONDUCTORS. away was destroyed at the same time, the flash going to earth by the roof of a conservatory. It was raining heavily, and the conductors were in good order. Note. — The futility of relying on individual rods without some system of inter-connection (see suggestion L.R.C.) is practically demonstrated, also the necessity of connecting up the smallest piece of metal work, as the iron support of the statue was selected in preference to the adjoining rods, whose air terminals were considerably higher. The circles O O O show the paths of the discharge. Fig. so. No. 68. St. Pancras Church, July, 1902 (Fig. 51). — The f-inch copper conductor was run from the spire, being looped round the square base of the gun-metal cross ; the earth connection was made by curling the cable and burying in charcoal. That the main flash travelled by the conductor was proved by the disturbance to the soil and the damage to the neighbouring cast-iron gas pipes, the lead packing being torn out, causing large escape of gas. The oscillatory discharge on the conductor caused a side flash to the iron radiator pipe, which slightly projected above the lead flat, the rather higher zinc cowl being untouched. The path was then made by the radiator- along the lead supply pipe to the feed cistern (fusing on its way a compo gas pipe and igniting the gas), then EXAMPLES OF LIGHTNING STROKE ON PROTECTED 67 BUILDINGS. by the overflow pipe to the gully on the right (Fig. 52). The electric fuses in the church were destroyed. Note. — -There were not sufficient metallic paths or earth connec- tions ; also the heating Fig, 52. system was not earthed. This is an example of the usual form of lightning conductors acting as well as could be expected under a moderate discharge; if a B flash had occurred, in all probability the lower portion of the building would have been greatly damaged and set on fire. Looping the cable which formed the earth connection is to be condemned; also, the position of the earth should not have been fixed so near the gas main. 68 MODERN LIGHTNING CONDUCTORS. No. 78. Inverness Post Office, August, 1900. — One conductor of -/^-inch strand copper projected above the roof and was earthed by soldering to a 12-inch water main. It was tested shortly after the occurrence, and found to be in good order; the resistance was about one ohm. The building was marked in several places and set on fire. On the east mansard roof it split the lead that covers the flat top in six places ; the two larger splits, 28 inches long each, were as if burned, the two shorter ones were like cuts with a knife. Below the west roof two discarded gutta-percha wires reached from the ceiling of a roorri on the third floor to within a foot of the iron hot-water pipes. The fire was caused by the light- ning passing by these wires, setting fire to the gutta-percha and the wood lining of the room. The pole on which the conductor was fixed also supported numerous telegraph wires. The conductor did not appear to have been struck. Note. — This is a very interesting case, showing that the number of telegraph wires do not afford protection to the roof on which they are fixed, and that it is necessary to connect the lead flats and iron portion of the building independently to earth as recommended by the L.R.C. Suggestion 6. No. 83. St. Michael's Church, Highgate, January, 1903. — The cross was struck, and one arm fell through the roof, the conductor, f inch diameter, was not damaged. The spire has been struck twice before, in 1856 and 1885. Note. — It appears that the copper dowel holding the cross was con- nected at the bottom of the spire to the conductor, but not at the top. A spark therefore took place through the stone work to the holdfast of the outside conductor, naturally splitting the cross. The cost of the repairs in 1885 is said to have been j£2oo. No. 86. Ainsworth Mill, Lancaster, February, 1903. — The buildings consisted of a stack, about 60 feet high, 1 5 feet square at base ; adjoining this was the engine-house. A conductor was on the chimney on the north side and ran to earth near the water lodge. The flash struck the chimney, the lower part first giving waj', crashing through the engine-house, and completely burj'ing the engine. Bricks were thrown violently in all directions, and for a radius of 300 yards scarcely a house escaped without a number of broken windows. Fig. S3 shows the exterior of the engine-house after the stroke. Note. — There is some doubt as to the continuity' of the conductor; if this was imperfect, it would account for the breakage where the stone base joined the brickwork. EXAMPLES OF LIGHTNING STROKE ON PROTECTED 69 BUILDINGS. Fig. 53- No. 88. St. Paul's Church, Bedford, March T4th, 1903 (Fig. 5S). — The Hghtning followed the conductor to the base of the spire, and then passed by the rain-water pipes, which are in different positions round the building. Most of the rain-water pipes are of cast iron, the others are of lead. The iron pipes are in several sections, and almost every one was more or less damaged or loosened. In several places they were broken at the joints and at the bottoms, whilst some of the lead ones were bulged as Fig. 54. The lead flashings of the opening through which the water runs from one roof to the next pipe were broken or twisted out of shape. On the roofs some of the lead flashings have been torn away from the walls. But the tremendous force exerted by the lightning can be better judged by the damage it caused inside the church. Passing through the roof at the south side of the tower, it moved, some three inches or more out of its place, the stout beam running along the top of the wall of the Lady Chapel ; while in the choir vestry on the other side of the church another thick beam was forced a quarter of an inch from the Fig. 54. wall, and one of the stone corbels supporting it was split through. The lightning also found its way into the small room at the end of the church and next the vestry which was formerly used as a dynamo room. In this chamber it tore from the wall an electric MODERN LIGHTNING CONDUCTORS. light bracket, and along the wire the lightning ran to the switchboard fixed in the church on the outer wall of the choir vestry. Here it fused the main switch, so that no light could be obtained until it was repaired. The fabric of the church itself fortunately escaped damage, beyond the decayed stone work being chipped here and there. _J. ^~lt ^ i*T« UV, Fig. 55- Pieces of roof were thrown 50 yards across the road through the Corn Exchange windows. Where the lightning ran down the lead pipes it did not fuse them. Note. — The oscillations set up in the copper conductor were distributed all over the roof, as there were no subsidiary conductors to form a path to earth, the current followed the lead flashings and descended by the rain-water pipes somewhat in the manner indicated by the o o o circles. All these pipes should have been connected to a horizontal conductor on the roof and again inter-connected near the ground. No. 93. Tower> of Coatbridge Church, Coatbridge, August, 1902. — The upper half of the tower is octagonal. The height from base to top of the eight cone-shaped stone balusters. A, EXAMPLES OF LIGHTNING STROKE ON PROTECTED 71 BUILDINGS. Fig. 56, is 80 feet. The conductor of copper wire rope (seven \ inch strands), ran from one baluster, A, to ground in a vertical line, fixed with metal holdfasts carrying glass insulators, I. The air terminal, with four points, C, projected well above the one baluster, and in addition there was a length of the same wire rope placed round the coping at the top of the tower, immediately below the eight balusters. This portion of the conductor had no insulators, and a loop was made at one end as shown in plan on Fig. 56, and the other was attached to the conductor. The light- » ning first struck three of the balusters, avoiding the air terminal, demolishing them, and passed by the hori- zontal cable, fusing it at the loop, to the main rod and to earth. There was no disturbance at the ground, the earth con- nection being good, but about 30 feet down from the air terminal a piece of stone, midway between two glass insulators, was splintered. The points of the air terminal do not appear to have been struck. Considerable damage to the roof was occasioned by the falling stones, and the necessary repairs cost .£^600 to i^700. The posi- tion of the three balusters p. g which were destroyed is shown by X X X and the path of the flash by o o o Note. — According to ordinary practice the tower would be considered protected, however the three points without conductors were selected. If a small wire had been run from the loop to the top of each baluster the lightning would have passed by the rod. The splintered stone was caused by the rod being held in insulators. 72 MODERN LIGHTNING CONDUCTORS. Victoria and Albert iVIuseum, August 17th, 1900. Observer : General Festing, Member Lightning Research Com- mittee. — An electric light main was struck, and the lead covering of the concentric cable was burnt away for a space about 3 inches by I inch, at a point where it rested on the parapet, alongside the edge of the gable. There were holes in the lead flashing and marks down to the lead stack pipe. The insulation between the conductors was apparently not injured, but a short circuit was found in a junction box. Note. — Apparently this was a side flash from the lightning conductor, which was on a high chimney stack, the flash passing by the roof to earth and part of it entering the cable. Where lead-covered cables are thus exposed, it would be desirable to earth the outer covering in several places. Hanslope Church, near Stony Stratford, April, 1904. Observer: W. P. Goulding, F.S.I. — |-inch copper tape con- ductor, let into chase in the tower face and carried through wall into the inside. One of the lower spires on the tower, immediately beneath the spire, was struck and the pinnacle destroyed. Note. — Leading the conductor inside the building is to be deprecated, but the belief in an area of protection and consequent absence of any conductor on the lower spires caused the damage. A conductor let into a chase is not so effective as one held a short distance away from the structure. L.R.C. Rule 3. Congregational Church, Queen's Road, Wey- bridge, struck March 20th, 1905. Observer : Arthur Goulding, F.S.I. — " The lightning conductor was one of Spratt's, put up in about i860. It consisted of woven copper wire .strands (about twelve in number). It was fixed to the rod at the top with a small copper tube, in which the wire was connected by a rivet, and was run about 2 inches from the walls by copper stays with glass insulators, lined with zinc. The tube was broken away and found lying on the ground, and the lightning conductor was hanging from the top. The effect of the shock on the conductor was to draw the strands tightly together in a zig-zag shape. No damage was apparently done to the steeple, but the gas fittings inside the church were affected, and the hot-water pipes broken in three places. The conductor descended to earth and was carried into the ground about 10 feet from the building, passing under some gas pipes in the church path. The current apparently went from the conductor to the gas pipes, the collar of one EXAMPLES OE LIGHTNING STROKE UNPROTECTED BUILDINGS. ON 73 of them being broken, and in my opinion was conducted along the pipes to the interior of the church. A curious feature in the case is that in the schoolroom, which is a detached building standing some feet from the church, a compo pipe in the wash-house, which is in the back of the schools and furthest away from the church, was fused and the gas ignited, and was discovered alight by the caretaker in the morning, having apparently been burning for about eight hours. Fortunately, there was no inflammable material near to it." Note. — This form of conductor is one which cannot be too strongly condemned ; however, singularly, in this case it preserved the fabric, although the conductor itself was de- stroyed. St. Botolph>^s Church, Cambridge, unprotected. Observer : W. Fawcett, M.A.— The lightning struck the south-east pinnacle A, ran down a rusty iron rod on to the lead roof B, from there it went to the lead fall pipe C. At D the lead had been changed to iron, and here it blew a hole about i foot 6 inches by 6 inches deep out of the wall with such force that a piece of stone broke the wall at the side of the buttress at E. (Fig. 57.) Note. — This clearly shows how the rain-water pipe acted as a con- ductor, and had it been continuous the damage would have been confined to the destruction of the pinnacle. Rockliffe Church, Car- lisle, November 8th, 1899, unpro- tected. — The Church, which is on Fig 57 74 MODERN LIGHTNING CONDUCTORS. an exposed position overlooking the Solway Firth, was almost wrecked ; the steeple was struck at its base, where it rested on a tower about 50 feet high. Most of the debris fell through the roof, forcing the windows outwards by reason of the compression of the air. Stones were hurled in all directions up to loo yards, one being found in a field nearly 200 yards from the spire. The damage was estimated at ^2,000. Note. — This was doubtless the result of a B flash, and shows the explosive action which naay occur. The disastrous results could only be minimised by the most complete system of protection. Godshill Church, Isle of Wight, January, 1904. Observer : Arthur Goulding, F.S.I. — Fig. 58. The light- ning, missing the flagstaff, struck the pinnacle and para- pet, passing be- tween the latter and the lead flat forming the tower roof, which was un- injured, acted as an explosive inside the tower, destroy- ing the stairs, clock casing (marked A), and deal panel- ling, falling on the tower arch next to the nave, broke Fig. 58. I i-j \ Fig. 59. Fig. 60. EXAMPLES OF LIGHTNING STROKE ON UNPROTECTED BUILDINGS. 75 all the windows, dislodged the basin of the font from its pedestal, doing minor injuries inside the building. The walls of the tower, 3 feet thick, were forced open at the quoins, and the clock face blown some 50 yards from the tower. Note. — The course of the flash is shown by the dotted line, and the case is interesting for two distinct reasons : First, that the high flagstaff, with metal vane, which certainly was a more salient feature and a better conductor than a stone pinnacle, was untouched, and, secondly, although the church had been previously struck in 1778 and in 1897, the insurance companies have not insisted on any system of protection. Fig. 59 is the end elevation ; D is the stove pipe (part of the flash went to earth near the base of this pipe) ; E is a lead gutter ; Fig. 60 is a plan ; A is point of first contact ; B, stove pipe ; C, damp place where earth was found. Fig. 61. Southborough Vicarage, Tunbridge Wells, May, 1903. Observer: C. H. Strange. — Detached building standing on a hill about 400 feet above sea level. The mechanical effect of the discharge was very great, the chimney struck being indicated by dotted lines, Fig. 61. It then blew out the face of the chimney breast in the bedroom below, as shown in Fig. 62, where B shows position of the bedstead, and finally wrecked the fireplace in the dining-room immediately under. During the same storm a number of the 76 MODERN LIGHTNING CONDUCTORS. incandescent lamps (unlighted) had their filaments broken. The photographs are by Lankester, Tunbridge Wells. Hanslope Parish Church, near Stony Stratford, Bucks, struck, April, 1904. Observer: W. P. Goulding, F.S.I. — This church is provided with a |-inch copper tape conductor let into a chase in the tower face, and carried through a hole in the tower wall and thence up the spire. The four pinnacles have each a re- volving copper vane. Side flash- ing from or perhaps avoiding the con- ductor, the light- ning struck the north-west pin- nacle, dislodging a piece of stone about a foot cube from the apex and squeezing the copper vane out of shape, doing no further damage. Fig. 62. Note. — The failure of the tape conductor was mainly due to its being run inside the tower wall ; also, its utility was lessened by being let into a chase instead of being carried on holdfasts outside the structure as recommended by the L.R.C. Rule 3. The Grange, Ramsgate, May, 1904. — This house con- sisted of three floors, surmounted by a tower on which there was a higher portion holding a flagstaff. The stroke passed by the wire guy-stays of the latter, and set the roof on fire. The damage incurred was said to be about ;^2,ooo. Note. — The folly of erecting a flagstaff, especially as arranged with disconnected supports, without a lightning conductor, is shown by the des- truction of one of the few architecturally elaborate residences in Ramsgate. EXAMPLES OF LIGHTNING STROKE UNPROTECTED BUILDINGS. ON 77 CirencesteP Station, Oct. 1901. Observer: C. Hooker, Surgeon. — Chimney split at X, large hole, B, in roof of porters' room, glass roofing of platform below D much broken; lightning went to earth by rain-water pipe, E, and iron column, G. T is a water Fig. 63. tank. Fig. 63 is from the observer's rough sketch ; the 000 show the direction of the flash, which was probably dispersed by the rails which are on the right. Note. — Stations are not often struck, owing to the protection afTorded by the numerous overhead wires ; the good earth by the rails probably prevented the flash from spreading laterally. No. 45. Cottages near Lewes, Sussex, August, 1901. Observer : H. C. Card. — Fig. 64 is taken from a photograph of the interior of the upper room of a cottage where two people were sleeping. The progress of the flash from the base of the chimney (shown by dotted lines) is illustrated by the dark marks on the plaster ; probably only a • small portion of the flash entered the room, escaping by perforating the sides of the roof in several places. The bedsteads do not appear to have been touched ; although it was said that " the occupants were thrown out," they more likely jumped out in their fright, as they were not severely hurt. The ceiling was on a slope from B and C upwards. 78 MODERN LIGHTNING CONDUCTORS, No. 6. All 1902. The tower was very much wrecked ; only one flash, and no rain until later. The church had been previously struck, and bells damaged, in 1827. Note. — The damage is of the kind which usually occurs with similar unprotected build- ings ; the point of interest is, as at Hutton Bursal, No. 50, Ipstones Church, and Godshill Church, the flagstaffs, with weather vanes, were not struck, the lightning falling on the upper part of the respective towers. Saints, Bpamham, Yorkshire, May, P'iG. 64. No. 10. Sewer Ventilating Shaft, Camberley, June, 1901. — The iron shaft, 20 feet high, was supposed to have acted as a lightning rod ; the stroke branching off among the drains in all directions, lifting a manhole weighing 2 cwt., and displacing it about 12 feet. Note. — As the house on the opposite side of the wall was struck, and the wall itself broken down, it is probable that the flash divided, the house and the shaft being struck at the same time. To avoid similar damage it would be quite easy to run a conductor from the base of the shaft into moist ground. No. 13. Upper Parkstone, Bournemouth, June, 1901. Observer: J. F. Fogerty, A.R.I.B.A. — The lightning struck the chimney stack at X, entered roof at B, passed to guttering, blowing off slates, thence to gutter, G, and to earth by rain-water pipe, which EXAMPLES OF LIGHTNING STROKE ON UNPROTECTED BUILDINGS. 79 was fractured at joints. See Fig. 65. Note. — This case is quoted because it shows the general course of a flash, and how easily the damage , could have been pre- vented by running a few small conductors from the top of the chimney to the guttering and rain-water pipes ; the latter prevented further damage by acting as a lightning rod, but as the joints were not bonded as recom- mended at page 29, their joints at the sockets were broken. oRw. Fig. 65 No. 21. Shop, New Road, Chatham, July, 1901. Observer : T. S. Addenbroke, Surveyor, War Department. — The ape.'c of gable struck ; the slates were pierced and the lightning followed the path of a J-inch gas pipe, which it fused for about 12 inches, setting the building on fire, earthing through the gas meter, which was not damaged. Note. — Here the small gas pipe offered a better path than the ironwork outside the building. This ought to have been connected with the ridge of roof and gable. No. 17. Gardener's Cottage, Camberley, July, 1900. Observer : G. B. Hartfur. — The builders were at work fixing the chimney pots when the lightning struck a scaffold pole considerably higher than the stacks, and at the same time the angle of the chimney stack, throwing the bricks some distance but leaving the newly-set pot undisturbed. No. 22. Greenhouse, South Shields, July, 1901. Observer : A. T. Flagg, Schoolmaster, who has furnished sketch. Fig. 66. — A glass-house, wires running from end to end just under the glass roof, one end nearly touching the last of a row of small trees. The leaves at A were singed, the lightning left a 80 MODERN LIGHTNING CONDUCTORS. track on the paint of the wooden knob B, broke the windows at C, split the wood under B, travelled along one of the wires, ripped the woodwork near E to get to the zinc pipe H and to earth ; at E an iron rod screwed to the post was forced away. Note.— This is a very interesting case, showing that the higher tree was ignored and the small wires perfectly conducted the flash without fusing same, and if they had been in contact with the pipe H probably even the glass would not have been broken. 'V- No. 27. Palmenston House School, Ross, August, 1901. Observer: Mrs. Evans, Principal. — This large stone building, the highest house in the immediate neighbourhood, was struck about 2 a.m., the lightning damaging the roof, Fig. 6^, just above Fig. 67. EXAMPLES OF LIGHTNING STROKE ON 81., UNPROTECTED BUILDINGS. where four boarders where sleeping ; they were uninjured, but the furniture was considerably damaged. Note. — The comparatively small damage was probably due to the very heavy rain, which allowed the greater portion of the stroke to escape down the walls, while a side flash only entered the building. No. 31. Tannery, Hylton Road, Worcester, July, 1900. Observer : A. B. Pinckney, R.I.B.A. — The chimney of the front office, a two-storied building adjoining an open space covered by an iron roof; on the other side of this was a high brick building used for storing bark, and a factory chimney 90 feet high. Ignoring the weather cock, which was close to, but much higher than, the office chimney, the latter was split off, the flash following the lead on the roof to the iron roof, earthing by the iron stanchions without further damage. Note;. — The protection afforded by the large metallic surface of the iron roof dispersed the flash, which otherwise would probably have blown out grates, &c. No. 32. Dwelling House, Sutton, July 1901. Observer: H. Gilbert. — Semi-detached villa. The chimney took the stroke ; it then entered sleeping room, setting fire to clothing of servant (severe burns to legs), tore out register, fractured mantel, passed to first floor, destroying mantel, and earthed by small gas pipe, laying bare the plaster. Slate roof, iron eaves, gutters, back and front. Note. — If a rod had been led, from the top of the chimney stacks over the ridge of roof to the guttering on each side, the rain-water pipes would have saved the damage to the interior of the house. Nos. 57A and 95 are very similar. No. 36. Wesleyan Chapel, Springbourne, near Bournemouth, July 1901, Observer : J. F. Fogerty, A.R.I. B.A. — A Boyle's ventilator was struck and knocked off, no interior damage. No. 26. Bridge of Weir Gas Works, Renfrewshire, July 1901. Observer : Captain Lloyd, R.E., Inspector of Explosives. — There were several stacks to these works, all surrounded by houses higher than themselves, the newest and tallest stack was damaged, there were two holes in the chimney, one about 3 feet below the top^ the other 8 feet lower, on the side which faced the "Wind. 82 MODERN LIGHTNING CONDUCTORS. K^ iJ^f i^o-i AiAi- L^U^-^ i>^^ Ljit^ Fig. 68. No. 42. St. Stephen's Church, Carnoustie, August 1901. Observer : J. P. Bruce, Architect, who gives sketch, Fig. 68. — The stone cap of belfry was dis- lodged, the light- ning passed in- side along chain pull of bell, which it broke, then es- caped through the rose window, part of the king post in roof being broken away; another part of stroke earthed inside by means \ of a gas pipe. Note. — The path through the window is ex- plained by the great resistance set up by the chain, each link of which would act somewhat like the coherer used in wireless telegraphy, and impede the current. No. 32A. Villas, Hayward's Heath, July 1901. Observer: Dr. Lee Jardine. — The flash destroyed chimney and part of roof and passed by rain-water pipes. No. 43. Gordon's College, Aberdeen, August 1901. Observer : The City Firemaster. — A building of two floors surmounted by an iron finial. The lightning entered the building and destroyed the electric light wires and telephones. No displacement of stones or slates. Note. — This was doubtless an A flash which found a ready path to earth by the electric circuits, as it destroyed the main fuses and their box. No. 54A. Cadet Armoury, Boston, Mass., June, 1902. Observer: W. G. Preston, Architect. — The flag pole, no feet long, about I foot diameter at base, fixed on the top of a fireproof building containing a large amount of steel work. The pole was much EXAMPLES OF LIGHTNING STROKE ON UNPROTECTED BUILDINGS. 83 splintered, see Fig. 69, but no further damage occurred. It was reported that the flash was seen passing from one iron portion to another. Note.— This is confirmatory of the opinion that lightning striking iron- frame buildings is often dispersed without damage to their structure. No. 51. Sherwood Street, York, August, 1901, Observer : W. J. Cudworth, Engineer, North Eastern Railway. — End house of a row. Chimney struck, flash descending by slates, stripping same from ridge to rain-water pipe for a space of 4 feet wide. Note. — The lightning took its usual course, and there would have been probably no damage at all if an -^-inch diameter iron wire had been run from the chimney to the pipe. It is interesting to note that as No. 44A and several other cases it was the end house that was struck. Fig. 69. No. 44A. Dwelling House, Conway, August 1901, Observer : G. M. Lee, Engineer, Postal Telegraphs. — This was the end house of a row. The lightning knocked off" the chimney, entered the house, and burst out the brickwork about 12 feet below the roof. No fire, bricks thrown 3 1 yards. Note. — In similar previous cases the damage has been less, owing to the flash taking the guttering and rain-water pipes ; in this instance there appears to have been no metal work outside. No. 57A. Cubbington, Warwickshire, February, 1902. — Workmen's Dwellings, School House and Residence. The lightning spread over the roofs of these low buildings, earthing by the rain- water pipes. MODERN LIGHTNING CONDUCTORS. Note. — The in- teresting feature of this case is the effect of one portion of the flash, which perfora- ted the brick wall (ij bricks thick) of the schoolmistress's house, where the pipe hook supported the gutter. It made a hole about \ inch wide, then jumped to a nail on which a small gilt frame was hanging, playing over the gild- ing, which appeared as if washed off; it then again pierced the wall near the bot- tom of the frame and escaped by the pipes. The Fig. 70 is taken from a photograph of "VMt^, f*i. sa? ;^., ^s^^*^^'^^: Fig. 70. %&,. \^\ '^ fti4ft. . high, had a copper conductor, \ inch diameter, projecting over the top, and , — , a telegraph pole was close to the building. In the plan (Fig. 72) A is the flagstaff, B the telegraph pole. The [J -^ s. 0-6 building was damaged ; coastguard who was standing at door C, injured. Note. — This shows that no reliance can be placed on the shielding effect of a conductor fixed to a higher point, and the station ought to have had a separate rod. Yig. 72. No. 32B. St. Dunstan's Church, Mayfield, July 1901. Observer ; Rev. G. Kirby. — Spire struck, ripping off" many of the shingles ; part of the flash entered the roof of the spire, wrecking the beams, cutting a piece 4 feet long out of a stay, then to earth at base ; the other branch ran down the roof to an iron gutter on north side of nave until it came to a stove pipe, 60 feet away, where it descended into the church and earthed, smashing up the floor as if a small mine had exploded. Daniage came to ;^50. School of Art, Birmingham, 1900, Protected. Observer: E. R. Taylor. — A ventilator on the gallery was struck near the con- ductor, which descended the wall from the higher part of the adjoining building. The rod was tested, and found to be in good working ord^r. Nobel's Explosives Company, Ardeer, Ayrshire, 1900. — The author had occasion to investigate the cause of the explosion of two of the detached buildings used for manufacturing gun cotton, and confirmed the opinion that it was due to lightning. The two buildings struck were not provided with conductors, and it appeared that the first one had received a direct flash, and the second. 86 MODERN LIGHTNING CONDUCTORS. which was some distance away, an induced current conveyed by the overhead electric light wires, which passed near both structures. The latter effect was probably facilitated by the leaden floors, which became charged, and sparked to some of the machinery used in the manufacture, and thence to earth. An interesting example of the erratic path of lightning will be found in Appendix A, No. 62, reported by Mr. W. Langdon, Past President, I.E.E. APPENDIX A. In the following tables will be found an analysis of reports selected from the L.R C. Observers' Reports on buildings which were furnished with CONDUCTORS* : — The principal causes of the failure of the usual style of lightning rod as fitted on the buildings investigated, appear to be due to the following : (i) Insufficient number of conductor and earth connections ; (2) the absence of any system of connecting the metallic portions of the buildings to the lightning conductor, especially the inter-connection of the finials, rain-water pipes, and gutters. The frequent damage by side-flash from the conductors might be lessened by running a horizontal conductor along the ridge, or along the parapets of all the roofs, somewhat after the method which is almost universally adopted in central Europe. The lightning strokes may be divided into three classes : (i) Those where the conductor conveyed a portion of the flash to earth but the side-flash to other unearthed metallic conductors damaged the building ; the practice of running the conductor round the projecting masonry, often taking sharp bends, doubtless facilitating the deviation of the current from its direct path to the earth. (2) In several observations a metallic roof of large area received the flash, consequently became highly charged, and the single conductor failed to convey the whole of the stroke, a portion of which took a circuitous path — for instance, through a speaking-tube and an electric bell wire. (3) A flash struck the building at two points simultaneously, a lightning conductor taking one part of the stroke, but damage was caused by the other portion selecting an unprotected part of the roof. Earth Connections. — With a few exceptions, these had the defect common to nearly all earth-plates which are simply buried in the ground close to the foundations of a building, and owing to drainage soon became dry, conse- quently are of very high resistance. Inter-connection with the Metal Work of a Building. — Although the utility of the external metal was specially put forward in the report of the Lightning Rod Conference in 1882, their recommendation has been apparently dis- regarded in all the cases under review. — Author. * The remarks were drawn up by Mr. J. Gavey, C.B., Engineer-in-Chief to the Post Office, and the Author. No. 74, column 4, should read " no conductor.' APPENDIX A.— Analysis of Sbi No. Description of Biiilding Effect of Discharge on Building Probablt 1 Dalston : German Lutheran Church. — Spire about 140 ft. high ; nave, 80 ft. long and 40 ft. high Reported by Mr; George Legg Fire, through ignition of gas at meter. Organ destroyed, and timbers of organ loft fired From vane vid pipe, lead flas meter ; thenc 2 TBnKO : Kea Church.— Wooden spire (88 ft. high) covered with copper Reported by Messrs. J. C. Daubuz and G. H. FeUowes Prynne Tiling damaged ; lead flashings turned back ; wall considerably shaken and face stones fractured Divided; part f part by alteri copper coverin from which it wall to lead fla 3 Stkadbroke, nb. Eye: Church. — Square tower with lead roof, flagstaff, and pin- nacles Reported by Mr. William Clutten Flagstaff shattered ; pinnacle badly damaged and had to be rebuilt; hole pierced in wall ; door to turret thrown off Passed from fla door of turret, conductor 15 PoBTSEA : Workhouse. - 2-storied block of buildings Reported by Mr. George Cowan Chimney and brickwork damaged; roof perforated ; casing of electric-light wires splintered and wires fused From chimney t along iron pit light wires 25 Daewen : Alexandra Hotel. — Irregularly built Reported by Mr. P. G. Ha worth, M.B., P. E. Met. Soc. Chimney broken ; grate displaced and marble fireplace broken down Down the interi 28 WalsaiiL : Shire Oak Brewery.— Chimney 70 ft. high Reported by Mr. G. H. Boulter. Bricks displaced at top of chimney, and earth dislodged at bottom of conductor Struck chimnej and then passe 30 Hampstead, Goi.der's Gkeen : Convalescent Home, formerly private residence Reported by Mr. Walter Hall Small hole made in apex of gable, casement of window damaged; plastering damaged and looking-glass smashed Uncertain 38 Woolwich : No. 12 Magazine.— Copper roof Communicated by H.M. Inspector of Submarine Defences. Uprights to fence or outer gate damaged Struck fence ; po 41 Leadb0bn: Signal Cabin.— Brick and wood Reported by Mr. James Wilson, and further by Mr. A. Clements, Super- intendent of Telegraphs, N. Brit. Bail- way Telegraph pole struck; train signalling instrument damaged; woodwork set on fire From pole along 54 Stoebhead Lighthouse. —Metal roof and iron railing around lighthouse Reported by Mr. J, M. Irvine, En- Wall damaged, bedstead scorched; gutta- percha wires of telephone circuit burned; woodwork set fire to Part at least took telephone wires to wires; thenc gineer t ■ 1 •DUiLDiNGs Struck, with Obsebvations by the Committee. ilmrge Character ot Oonductor Woven copper baud (Spratt's), 3 oz. to the foot Copper tape 1^ in. by Copper rope fin., dia. No conductor in part of building damaged Copper rod (good quality) I in. diameter Conditions condacing to Discharge through Building Insufficient Number of Conductors being highest point should also have been protected Copper tape and rod carried 4 ft. above chimney Copper rope | in. and I in. diameter, and rod f in. Three points Cabin not protected Copper rod f in. or J in. diameter Formerly ductors on chimneys ; now only three con- all Only one finial point protected ; three without conductors Quality of Earth Connection Bad ; only a few inches of oonductor into guUey [ Good earth Very bad earth ; rope merely knotted and passed through stone 18 in. below surface. Besistance to earth very high Character not stated Character not stated Earth not good. Eesist- ance from ground line 29 ohms Alternative Paths of Discharge (unearthed) Bain-water pipe, lead I Bad earth ; neither lead flashing nor wat flashing. Bain-water pipe and gas-pipes not earthed or connected to conductor Copper sheathing of spire, rain-water pipe, and copper wire which passed over conductor and near pipe Iron railings ; speaking- tube and telephone pipes connected to earth though in clo proximity to conductor ; the lightning r( itself carried too close to the gas pipei the gas meter not bridged over by a oo' duetor joining the inlet and outlet pipes The rain water down pipes shoijld have bet connected with the roof metals, i.e. to tl copper roof and lead flashings, and als to earth. This would have prevented tl side flash and consequent damage Earth bad. The failure to provide a branc conductor from the flagstaff to the mai oonductor, and the omission to earth tl lead flashing, real cause of damage Insufficient number of conductors to protei the whole range of buildings, and meti projections on roof not connected to eartl Insufficient number of conductors to prote( entire building ; of the seven chimneys, a of the same height, only three protectee the nearest conductor 41 ft. from the poii struck. This is probably a good iUustratio of the B flash. At about the same tim a horse was killed in a field outside tl town Building occupying the highest ground i the neighbourhood. Illustrates fact tW lightning conductors on a shaft shou terminate at the upper extremity in mann recommended by Committee All the finials should have been connecti by subsidiary conductors to earth Magazine well protected against lightni discharges ; the damaged post do far fn magazine that no protection afforded lightning rods. Probably a B flash Lightning protectors provided on all t( graph instruments. The one in quest) did not act efficiently An isolated building on an eminence ._ copper speaking-tube and the iron raii around the lighthouse should have " connected to independent earths APPENDIX A.— Analysis of Sej 56 57 60 62 64 65 Description of Buiiding 67 Devaae Lighthouse. —Iron lantern frame ; copper dome, 130 ft. high ; dwelling-houses 30 ft. from tower ; lead roof and lead down pipes leading to enclosed cisterns or tanks Beported by Mr. C. Dick Peddle EooHDALE : Stricklands Brewery. — Stone building, tail chimney, iron band round base of chimney Reported by Mr. H. Frost, Sectional Engineer, P. 0. Telegraphs WiTHERNSEA : Signal box, wooden cabin Reported by Mr. W. G. Oudworth, Engineer N. E. Railway Blea Moor: Midland Eailway line. — A guide post on footpath struck and charge entered wooden casing carrying cables, mounted on short oreosoted pillars 12 in. above ballast Reported by Mr. W. Langdon Cambridge : Cavendish Laboratory Reported by Mr. W. M. Paweett, M.A., P.S.A. Maidenhead : Church of All Saints. Reported by Mr. Arthur Goulding. 66 Mark's Tey, St. Andrew's Church : Tower of oak ; wooden spire covered with oak shingles Reported by Mr. W. Cressall PossiNQwoRTH HousE, Cross-in-Hand : Private dwelling Reported by Mr. Killingworth Hedges, M. Inst. C,E. Effect of Discharge on Building Hole pierced in lead whistle-pipe ; whistle and pipe fused, dwelling-houses near damaged ; tank-covers weighing 28 lb. displaced 3 ft. Chimney cracked 15 ft. above shed abutting on stack ; portion of rod above chimney broken off Window sash and frame of building fired. Block and bell instruments smashed and scattered in all directions Guide post shivered into fragments. Boxing displaced and split Open for a distance of 33 ft. Displaced tiles ; made hole through sill of dormer and fused gas pipe Cook on finial of tower knocked off the spindle, breaking some tiles in its fall Displaced weathercock and disturbed some bricks Building struck twice. First case struck and displaced conductor, and also did damage to chimney and slates. Second case destroyed chimney, damaged roof, and part of the divided flash struck statue not provided with rod ii ] s Steuck, with Obsbbvations by the Committee — continued. Character o£ Conductor Conditions conducing to Discharge through Building Insufficient Number of Conductors Quality of Earth Connection Alternate Paths of Discharge (unearthed) Copper rod | in. dia- meter. Forked finial Eod with three prongs Copper wire rope f in. diameter on tower Finial rod f in. iron 6 ft. above apex of spire ; 4 in. wire rope Copper wire rope, J m. diameter ; single pointed terminal Copper tape, 1^ in. Conductor on tower 36 ft. from point struck Two earth plates 20 in, bylOin. bylfin., 6£t. apart, connected by rod. Soil not of the best Character of earth un- known Not stated, but the rod had been recently fixed Stated no earth plate Not stated Everychimney-stack Good, fitted with a rod. | The flash struck the rods on both occasions about 3 feet below the air terminal Whistle-pipes formed al- ternate path Brass knob to iron rod and lead cheek of dormer and gas pipe The tape conductor was run indirectlyto earth, so thai; a portion of the charge travelled down the wet roof Another ease illustrating defects and 54 ; all metallic masses outside the tower should have connected and well earthed positions. Spires or towers- w roofs should be provided with i independent conductors, one on No sufficient data could be obtain of a definite opinion as to cause Somewhat similar case to 41. entered signal-box along telegi and the instrument-protector fa An interesting case illustrating e chosen by lightning. A passag earth, up a wooden post, and in casing to reach the metallic si lead-covered cable, which it tr some distance before it enteri chanical signal wire. This und circumstances would appear an route. The charge only read earth when it entered the rails Illustrates the need for earthing i portions on the roof of a buildir The cock formed an imperfect minal to the lightning rod ; i this the rod acted efficiently Beyond displacing weathercock a few bricks where the rod i ground, no damage done ; alth rently not efficiently terminate end the rod conveyed the char earth These two cases can only be explained on the supposition it charges were of the B type hypothesis is supported by th numerous trees in the neighbor struck. An unusual number ( rods were provided, although th interconnected. It will be not structure did not suffer ai damage, so that the rods aSi measure of protection ; arid if th connected by a horizontal cor nished with more direct earth cor damage might possibly not hav APPENDIX A.— Analysis op Sbi Description of Building St. Panoras' Chukoh, Euston : Spire sur- mounted by gun-metal cross. Lead roof Reported by Mr. Arthur E. Kelly Swansoombe: Church, with oak shingled spire Reported by Mr. W. P. Goulding AiiDENHAM Church, near Watford, Herts. — Timber spire on top of tower. Clock chamber some 20 ft. below lead flat of tower ; clock weight exposed through belfry, but below belfry cased in down to floor of church, where there is a pit 6 ft. deep to receive it Independent reports by Messrs. Harry G. Assiter and Fred. V. Selfe St. Botolph's, Aldoaie : Church with tower and spire Reported by Mr. Killingworth Hedges, M.Inst. C.E. Kingston: Boys' School.— 200 ft. by 50 ft. 60 ft. to ridge of roof ' ' I Mr. Isaac Slade Invekness: Post Office. — Standard over- topped mansard roof by 12 ft., and had 15 wires attached to it. Flat tops of mansard roofs covered with sheet lead Reported by Mr. J. M. Irvine, Engineer P.O. Telegraphs Benefield : Church with tower and spire surmounted by a copper cross Reported by Mr. Fred V. Selfe Effect of Biscbarge on Building Gas-pipe fused and gas ignited in church ; joints in buried gas-pipe parallel to and 16 ft. from buried end of conductor de- stroyed ; large escapes of gas .caused ; electric light fuses destroyed Fire ; portion of church destroyed Copper weathercock twisted ; oak timbers and shingles of spire shattered; wood casing for clock weights, and oily rags at base thereof, ignited Parapet under spire shattered. Finial to which conductor connected disturbed at base Chimiiey stack damaged. Picture hung with wire scorched Lead on roof damaged. Below roof two discarded gutta-percha covered wires (reaching from ceiling to within a foot of iron hot-water pipes on floor) set fire to, and wood lining of rooms ignited Displacement and bulging of spire, threaten- ing its collapse ; supposed to have been caused by lightning. No direct evidence [ iii ] iLDiNGs Steuck, WITH Obseevations BY THE GoMuiyiEE—oontimied. Character of Conductor Copper stranded cable 4 in. diameter looped round square base of gun-metal cross on top of spire, then to lead roof and to earth i in. solid iron rod in 10 ft. lengths united by plumber's joints; ended 2 ft. above earth on iron gas barrel, but (said to be) not con- nected Copper cable, 1 in. dia- meter; connected to finial Not stated One conductor, fy in. strand, copper, 12 ft. above roof fastened with galvanised iron staples. Wires at top were untwisted, sepa- rated, and sharpened at points; at bottom were soldered to 12-in. iron water-main pipe, after encircling it several times Not stated Conditions condacing to Discharge through Building Insufficient Number of Conductors Insufficient number of conductors Quality of Earth Connection Eod ended in an iron tube which entered ground. Earth very bad Not stated Not stated Said to be faulty Alternative Patis of Discharge (unearthed) Alternative path formed by relief pipe (which protruded above roof) hot-water system, and finally to earth vid gas-^ipes Conductor followed side of iron down pipe ; dis- tance between not stated From copper cross and upright to cross beams supporting same Most interesting and instructive case, lightning charge evidently struck the and set up violent electrical oscillation the lead roof with which it was in metf contact at one end. Had suitable ei connections been provided at the disi end of the nave, and had the heal system been also connected to earth, damage would have occurred. The c outlet to earth for the charge was the gas-pipe ; hence the damage An imperfect rod with very bad ea Apparently the charge entered the to at the lower opening and found its ' to earth, setting fire to the staircase in passage An interesting case in which the meta bell-cord acted as a lightning rod, dam being restricted to the upper and lo extremities only The lightning rod took several sharp anj that may have caused side flash, wh reporter thinks passed on to earth via rain-water pipe, which was near but connected to the rod Damage probably due to two causes : fi a single lightning rod of moderate hei quite insufficient to afford reasonable j tection even against A flashes; a secondly, the interior pipes for heating i other purposes formed an alternative p which could only be reached by a fract of some part of the structure The damage was probably due to the that the lead flats and the iron porti of the building were not connected earth A case in which upper portion of spire fo to be damaged in a manner which might 1 occurred had a lightning flash followed course of the copper cross with its met support, then flashed through stonewor the conductor. Indirect evidence only APPENDIX A.— Analysis of Si No. 80 83 85 86 Description o£ Building Effect of Discharge on Building 93 94 97 98 Welbeok Abbey : Library and chapel. — Beotangular building— oopper-oovered roof Beported by Mr. J. Wallace Stevens Hiqhgate: St. Michael's Church. — Tower and spire surmounted by stone cross, 145 ft. high Reported by Mr. Walter Hall and Mr. KiUingworth Hedges Derby : Carriage sheds. — Midland railway Beported by Mr. W. Langdon Bolton: Ainsworth Mill. — Chimney about 60 ft. high Beported by Mr. W. W. Midgley, F. E. Met. Soc. Bedfobd: St. Paul's Church.— Tower and spire Beported by Mr. W. P. Goulding CoATBBiDGE, LiNABKSHiBE : Church. — Tower about 80 ft. high, upper half octagonal, carrying eight cone-shaped balusters, oneat junction of each angle Beported by Mr. W. E. A. Knight ToBR Head : Coast Guard Station Beported by Mr. T. Patterson, P. 0. Engineer Canton, Cardiff : St. John's Church. — From top of steeple to ground, about 175 ft. Beported by Mr. W. H. Monk, P.O. Telegraph Superintendent East London Waterworks: Chimney of Pumping Station, Sunbury. Beported by Mr. W. B. Bryan, M.Inst.C.B., Chief Engineer Window sill broken and pieces thrown about ; rain-water pipe (sunk m wall) bared One arm of stone finial cross broken and displaced ; ball of cross shattered ; falling stones crashed through roof of nave Shed itself unhurt, but discharge struck gas-pipe on roof of carriage and ignited Chimney demolished. Windows of mill broken; gas-pipe fused and gas ignited. Engine-house destroyed by falling chimney Heavy beams inside building slightly dis- placed, supporting corbels split ; main switch of electric light fused. Iron rain- water pipes broken ; lead flashings on roof broken and torn away Three balusters damaged and part of con- ductor rod led round toWer fused. Boof damaged by falling stones All wmdows smashed ; hon eaves gutter N( smashed; telephone wires fused Conductor torn away at about 30 ft. from A the trident; electric-light wire fused; J plaster damaged in several places; lead on lower roof ripped up ; and stone oopmg torn away where lightning left conductor for the leads Struck upper cornice of campanile, then lower cornice, shattering stonework above and below [ iv ] iLDiNGs Struck, with Obsbbtations by the Committee — continued. Ohaxacter of Conductor Two conductors, copper wire twisted h in. dia- meter Copper rod, | in. dia- meter Not known, but said not to be in good repair Copper cable | in. dia- meter terminated under seat of weathercock. From the base of the spire the conductor was laid on the lead flat Copper rope of seven strands from above balusters to earth. A subsidiary conductor carried around at the base of the balusters and connected to main rod Building itself not pro- tected. Flagstaff which is apart from but close to the building pro- tected by conductor One conductor ; trident at top, and about 12 ft. of iron casing at bottom No special conductor, as the 36-in. steel stand- pipe connected to several miles of mains came almost to the top of chimney CoadltiouB conducing to Discharge through Building Insuflacient Number of Conductors Quality of Earth Connection Earth connections bad (Details unknown) Found to be in connec- tion with the electric- light mains Unknown Alternative Paths of Discharge (unearthed) Not stated Earth bad ; conductor buried in cement Bad. Earth jilate 1 in. wide, and about a yard long, buried about 10 in. beneath surface in very dry soil Eaiuing heavily Formed by lead roof and rain pipes &c. Remarks insignificant, probabl; oscillatory side flash from the i to the rain-water down pipes ^ not in metallic connection A stroke caused similar damage i ago One of fourteen railway carriage in a light timber shed unprov conductor The fall of the chimney wrecked house, and the mass of d^bi great as to prevent further im The flash would appear to ha' path along the interior of the i preference to that furnished h lightning rod, for it burst out structive violence at the bai chimney, causing the collapse of A very interesting case. The being in contact with the lead 1 oscillations were set up whicl the whole length of the roof ; no conductors being provided, the took all available paths, some some outside the bmlding A conductor on each baluster reat to the circular band at the bi balusters would have prevented i Had a good earth been providi conductor on the flagpost pro damage would not have occurred The lightning rod very old and thin where it passed through tl conductor fused and main chari to the lead flashing of the lower shows the necessity of running earth and. avoiding sharp bends This proves that a flash will follow of hot air, and in this case wi from the standpipe which forme conductor to earth CHAPTER VIII. INSURANCE COMPANIES.— TREES AND LIGHTNING STROKE. ?,NSURANCE against damage by lightning is now included in most policies, and it would be imagined that the companies would reduce the risk as much as possible by recommending the protection of buildings, or at any rate see that an efficient lightning conductor is installed after an insured building has been struck. There are many instances of churches being struck more than once, but they remain unprotected. Godshill Church, Isle of Wight has suffered by three strokes (see page 74), but up to the time the L.R.C. observer made his last report, nothing had been done in view of the possi- bility of a fourth stroke. The insurance offices do not seem to care whether a building is protected or not, as no individual office likes to insist on the erection of lightning conductors for fear of diverting business to its rivals. The amount of damage to property by lightning stroke is enormous ; most people think that almost every church has a con- ductor, whereas not 10 per cent, are so provided, in fact, although there is sometimes a recommendation from the archdeacon that the churchwarden should put up a conductor and see that it is kept in order, if the vicar wishes to safeguard his church the cost usually has to come out of his own pocket. The present attitude of insurance companies is somewhat similar to that following the introduction of electric light ; at first, as regards wiring, it was go as you please, but the frequent electrical fires roused the companies, who, borrowing advice from the United States, began one by one to draw up rules, until at the present time almost every company of importance has its electrical inspector. 88 MODERN LIGHTNING CONDUCTORS. In Michigan, U.S.A., the number of cases of damage by lightning stroke reported to the Commissioner of Insurance in 1895 was 316, covering damages amounting to $37,563, in the following year the number of cases rose to 1,509, and the damages to $143,841. This increase might be abnormal, and in making statistics one must compare the average of a certain number of years with the average of a similar number of preceding years. The most comprehensive statistics for the study of secular variation in damaging lightning strokes are those of the German Empire. Dr. Wm. von Bezold as early as 1869, in a study of the statistics collected by insurance associations in Bavaria, expressed the opinion that there was a steady increase in danger from damaging lightning strokes. He again took up the subject in 1874 and in 1884, finding in both cases a continuation of the increase first noted in 1869. Mr. Kasner confirms the increase for the province of Saxony and the Duchy of Anhalt. " In the flat country there were 804 cases of damaging stroke for the five years 1887 to 1891, as against 1,088 in the five years from 1893 to 1897, an increase of 35'3 per cent." He also shows that the danger from lightning in the country is nearly four times as great as in the cities. In Schleswig-Holstein some of the insurance companies bear a part of the expense of fitting conductors to buildings insured by them. The East Prussian Fire Insurance Company bears half the cost ; others make a reduction in the annual premium-. The former course is preferable, as being more attractive than an annual reduction ; it is more convenient to the house owner to pay a slightly higher premium each year, than to disburse at a given moment the whole cost of installation. In Holland the total sum paid out by the larger Dutch companies for losses through fire was in 1905, ;£^i, 343,750, of which ;^84,333, or 6'28 per cent., was due to lightning. In Schleswig- Holstein the following reductions are made : — For slated or tiled For thatched houses 20 per cent, houses ... ... 5 per cent. „ windmills ... 20 „ ,, For schools ... 10 „ ,, „ churches ... 50 ,, ,, TREES AND LIGHTNING STROKE. Whether forest trees act preventively, like a multitude of lightning conductors, is an open question. In the report of the Lightning Rod Conference, 1882, ashes, elms, oaks, and poplars are called dangerous ; beeches, birches, and maples are mentioned as TREES AND LIGHTNING STROKE. 89 hardly ever touched by lightning, and this view was brought forward by Mr. Hugh Maxwell, of Massachusetts, as long ago as 1787. A very elaborate investigation of the underlying causes of the seenning preference of lightning for certain trees was made by Mr. D. Jonesco,* in Stuttgart. He laid aside, as having little or no influence, such physical conditions as the characters of the soil, whether dry or moist, and the depth to which the roots penetrate. His observations seemed to show that trees are liable to be struck when starch- producing and not when' fat-producing — as oaks, willows, poplars produce hardly any oil, others, lime trees and firs, according to the season, oil or fat. The wood of those trees rich in fatty material was in all cases a poor conductor of electricity ; on the contrary, the trees rich in starchy materials conducted electricity very well, and no important differences were noted for the various kinds of wood. Poplars have been studied, and it has been proposed to utilise them as lightning rods, by providing them with iron belts and earth plates. According to Hess,t when the branches come nearly to the ground, and where the soil is damp, they would be useful in protecting a building. The following is a Table prepared by the Dutch Meteorological Institution of the strokes on various trees between 1885 and 1902: — Poplars Oaks ... Willow Yew . . . Firs ... Pear tree Oak ... Lime ... 232 times. Walnut ... 130 „ Beech 70 ., Chestnut 5° » Apple tree 27 >, Cherry ... 25 ,> Alder 18 „ Birch 14 „ times. 5 5 5 4 4 2 "The German Government caused, in 1899, an enquiry to be made into the subject of lightning and its effect upon trees, the observations having 'been entrusted to the overseers of nine foresting stations scattered throughout an area of nearly 50 thousand acres in the district of Lippe. It was found that of all forest trees the oak was most susceptible to the attacks of lightning. The forests were found to comprise various kinds of trees in the following proportions : beech, 70 per cent. ; oak, 1 1 per cent. ; pine, 13 per cent. ; and fir, 6 per cent. ; of the 275 trees which suffered * " Ursachen den Blitzschlage in Baume." Stuttgart, 1892. t Elektro. Zeitschrift, 1900. 90 MODERN LIGHTNING CONDUCTORS. from lightning during a period of several years, no fewer than 58 per cent, were oaks, 21 per cent, firs, 8 per cent, beeches, and 7 per cent, pines. There were 6 per cent, of other kinds of trees." " It is noteworthy it has been stated by some English authorities that the beech is seldom or never struck by lightning. The truth of this statement has long been disproved, and it is interesting to see that the beech in Germany appears to be more often the subject of lightning stroke than the pine." — Chambers' Journal, 1900. The following is an extract from Captain Maclean's paper on the Action of Lightning, 1 890. " The injury to trees are of two kinds ; the first, far the most common, is simply to score out the bark up the trunk of the tree, out along one limb and, then, perhaps, the marks are seen on two or three of the upper branches to the outer twigs. In some cases the whole of the bark on one side is blown off as well. The rain is falling, and one or more streams of water are running down the sides of a tree, forming a conductor which becomes insufficient at the time of the discharge to carry off all the electricity, and therefore it becomes .so suddenly converted into steam as to blow out the bark along the line ; and if there is any communication with the sap by knot- hole or other flaw, the sap is also converted into steam and the bark blown off. The other form is the shattering of the tree, which I imagine to occur when the electricity is insufficiently carried off by the outer surface, and collects at the junction of some main branch with either the stem or with some other branch, where there is, perhaps, a cavity with water in it, or a collection of moist dead leaves, the tree is then easily rent by the explosion of steam generated. If the tension be very great, and especially if the air round the tree be dry, the sap may be violently exploded, and the trunk splintered and shattered as if by dynamite. Of the trees examined, the only ones shattered were those struck before the rain fell, the others were scored simply, with bark blown off." 90a THE EFFECTS OF LIGHTNING ON MANKIND. There are few natural phenomena which make so deep an impression on mankind as thunder and Hghtning. Although we have ceased wondering at the developments of electricity — which is success- fully harnessed as a rival to steam for the propulsion of trains, and companies vie with one another for the right to distribute electrical power at a pressure which would be extremely dangerous unless under proper control — a thunderstorm is considered a far more serious matter, and many instinctively dread it, knowing that there is a chance, perhaps very remote, of their being struck ; besides, every storm entails a real danger to property. To a large extent the feeling is the relic of the superstitions of our forefathers, who regarded lightning as the direct manifestation of the wrath of some offended deity. In the time of the Romans, persons killed by lightning were considered to be hateful to the gods, and were buried by themselves, lest the ashes of other men should receive pollution from them. It is curious to note that at the present time the same buildings are occasionally again and again struck, and that certain localities are visited by thunderstorms more than others ; a fact which has been taken advantage of by the witch-doctors in South Africa, who are said to stand fearlessly in a certain spot during a terrific storm, whereas in the vicinity it would probably be very dangerous to do so, because the large amount of minerals in the rocks might divert the lightning. The superstition of the ancients may appear in this twentieth century to be extremely ridiculous to us ; but we should not overlook the fact that when Benjamin Franklin — whose memory has been honoured by the erection of a statue in Paris on the two hundredth anniversary of his birthday — introduced the lightning- conductor, for many years his invention was opposed on the plea that " it was as impious to erect rods to ward off Heaven's lightnings as for a child to ward off the chastening-rod of its father." * " Even to-day the brilliancy of lightning hides itself from us in the darkness of impenetrable mystery, but we feel that there is an immeasurable power and unimaginable force which rules us. In increasing our observations and in comparing those which are analogous, we may hope if not to arrive at an immediate conclusion * "Thunder and Lightning"— FlamMARION. 9U MODERN IIGHTNJNQ CONDUCTORS, ::r^: >' ^\ ^ .^>. ll •»s.'^?' .'f r<^^ ^:^ ! •>. 'C''^^:J -■•' y<^~: ^"£>^ ^■^■. - 't "^ tf'S- ■^r-;i \» - mi^M;^ -^ 'v^' -§v "--;■--,■ 4 ■'">s B^ > ■' l^y' --^"•^>.)S'»' i' :iP^:* (;« si o K O m *— ' ■**iJSa*^T.- 1 *!^ f 1| 1 THE EFFECTS OF LIGHTNING ON MANKIND. 92a at least to help on the work of discovering what laws govern this subtle and imponderable fluid. " Here it will strike a man dead without leaving a trace ; there it will only attack the clothes and insinuate itself as far as the skin with- out grazing it. It will burn the lining of a garment and leave the material of which it is made intact. Sometimes it profits by the bewilderment caused by its dazzling light, to entirely undress a person and leave him naked and inanimate, but with no external wound, not even a scratch. " It would seem as if lightning were a subtle being. We see it twisting into space moving with astonishing dexterity among men, appearing and disappearing with the rapidity . . of lightning it is impossible to define its nature. At all events, it is a great mis- take to trifle with it. It means running great risks." The indiscretion of Dr. Richmann in 1753 may be quoted as an example. He had fixed an iron rod to the roof of his laboratory and was accustomed to measure the intensity of the electricity, but during a thunderstorm approached too closely to the conductors and was immediately struck dead. Barham Church illustrates the way in which a flash, of probably the B type,* behaves inside a building — fortunately on this occasion without loss of life. The worshippers at the Cathedral of Avila, Spain, were not so fortunate. It is reported that in May, 1909, the lightning stroke killed the officiating priest and three ladies at the altar, which was set on fire. At Barham the lightning struck the church on either side of the gable cross at the east end, and entered in two places. The tower, which had a small fleche, upon it, was untouched, and so were the numerous tall elms and limes round and in the church- yard. One stroke passed down and through the east window, breaking the stonework and shattering the altar top, a slab of marble six inches thick; it wrecked the marble steps, and escaped by the hot water pipes, which were for some yards broken to pieces. The other part of the same flash took a more zig-zag direction, entering the church by the sill of the window and coming out through the wall, forcing its way through the marble pavement and making a small hole near the hot water apparatus. The subtleties of lightning are so inexplicable and its visitations are so numerous that it is impossible to describe the many fatal and *Page 9. 93a modern lightning CONDUCTORS. serious accidents which yearly take place, and the question naturally ^"^^S WHERE TO SEEK SAFETY DURING A STORM. The first and principal rule to observe is not to get under a tree, or even stand near the lateral branches. Even if a small portion of the flash should travel over the wet leaves, a person under- neath would form a convenient path for the lightning to pass to earth. It is equally dangerous to take shelter alongside a building or close to a hay stack, for a similar reason, as the rain dripping off the roof may lead the flash in the direction where one is standing. Several Effects of Lightning on the Chapel, Thirsk. accidents have also occurred to persons who have entered unfinished houses, where the scaffold poles have acted as conductors. The path taken by a lightning stroke is shown by the illustration of the Chapel at Thirsk. It will be seen that although the ventilator on the roof was struck, a portion of the flash jumped to the rain water pipe and part descended from the rain water gutter at points where it overflowed. The photograph is also interesting as showing there was no protection from the lofty spire of the church, which was quite close and was not struck. A wide berth should be given to telegraph posts, and the telephone should never be used during a violent storm. Do not stand near any rain water or ventilating pipes, and keep away from lightning conductors. WHERE TO SEEK SAFETY DURING A STORM. 94a Trees act to a certain extent as lightning rods, so that anyone is fairly secure in their neighbourhood — safer, in fact, than on a treeless plain. Probably if the traveller is getting very wet it is best to take shelter under a hedge or in a low copse, but on a moor or common the wisest plan is to lie down during the height of the storm. Under no circumstances should a bicycle be ridden or led, nor should an umbrella, or long fishing rod be held up. It is not that the lightning is directly attracted by such objects, but a flash on its way to earth gives out innumerable smaller discharges, so that to be near any objects containing metal, or one that projects into the air which may be selected as offering the best path, is, to say the least, unwise, as it should be remembered that a shock which may only cause minor injuries if one's clothes were dry, might prove fatal to a person who has been some time out in the rain. The safest place is undoubtedly inside a house. It is remarkable that although there were many injuries and marvellous escapes, there were only two serious accidents among the 115 cases of buildings struck which were sent in by the observers to the Lightning Research Committee, 1 901 -1904. The following suggestions may be made : Keep away as far as possible from the fire place, as if the chimney is struck the grate and surroundings will almost invariably be blown out into the room. Hot water pipes are very likely to be selected, and they should be avoided during a storm ; also do not sit in a greenhouse or a con- servatory, as a portion of a flash may pass down the training wires and other metal work, and do not take shelter in a farm building where animals are collected. The idea that glass attracts lightning is absurd, and if one does not mind the glare of the lightning there is no evidence to show that it is unsafe to approach the windows ; it is better, however, to keep them shut. TO RESTORE CONSCIOUSNESS IN THE CASE OF A PERSON STRUCK BY LIGHTNING. 1. Make the subject breathe by artificially imitating the respiratory move- ments of the chest. 2. Keep the body warm. 3. Send for a doctor. Of the visible effects of lightning stroke upon the human body little more can be said than that sometimes burns, usually superficial, have been noticed. Frequently red lines or markings are noticed 95a MODERN LIGHTNING CONDUCTORS. which are probably localized conjestions of the small blood vessels of the skin. These, from their irregularities and branchings, have led to the fanciful idea of photographs of trees, etc. It may be said that lightning frequently causes a temporary paralysis of the respiratory organs and heart, which if left alone will deepen into death, but intelligently treated, will generally result in recovery. UPWARD DISCHARGES OF LIGHTNING. As a rule we imagine that lightning always descends, that it comes from the higher celestial regions to be lost in the common reservoir, but this is not always the case, sometimes it re-ascends ; thatisto say, after it -^^^^^ reaches the '^j^^^^^^^ ground it travels through the earth to a point where the resistance of the air is less than from where it des- cended and again escapes to a cloud. The illustration shows a downward discharge taking place at one point and a corresponding upward discharge is shown at some distance away. There are instances of people being seriously injured by a reverse stroke, and in some parts of South Africa the shocks from the ground are very severe. The engineer of the railway which was being con- structed near Fourteen Streams told the author "that the Kaffirs sometimes knocked off work, as they could not handle the rails, which were highly charged, although no lightning was visible." The upward stroke of lightning has been noticed by Professor Platania after a storm in September, 1906, which caused much damage to the Florini Palace, near Catania, Sicily, recently fitted with a complete system of lightning conductors. It appeared that the upper terminals had not received the flash, but that the direction of the discharge was from the positive electricity of the ground to the negative of the clouds. Doctor Folgherarter found UPWARD DISCHARGES OF LIGHTNING. 96a in the Roman Campagna six cases which showed an upward stroke, and *Professor Max Toepler, in his paper " On the Direction of Electric Streams in Lightning," describes twenty-nine cases of direct and thirty-three reverse strokes. The author noticed that a slight crater was formed in the ground where an upward stroke had taken place during a violent storm near Colorado Springs, U.S.A. LIGHTNING ON THE HIGH ALPS. Messrs. Hutchinson and Ward, of Oxford, had some interesting experiences when they stayed at the Margherita Hut on Monte Rosa for a period of eight days in August, 1907, for the purpose of investi- gating human respiration at an altitude of 15,000 feet, on behalf of the Royal Society. When a thunderstorm took place and the cloud was below the hut gorgeous brush discharges pointing downwards took place from pieces of wood on the roof, but when the cloud rose above the hut the discharges were upwards ; a frozen piece of paper also gave out a luminous discharge. They also experienced the effect of actually being in a storm-cloud. Mr. Hutchinson's account is as follows : " First it hailed very hard, round hailstones just half-an-inch in diameter, then the lightning fell all round and very frequently on the hut, which was completely coated with copper and furnished with bunches of spikes in prominent places — the structure is held down by cables which are fixed to the copper . All we could see was a rather pale flash, very dazzling, the roof hissing as it was struck, but we felt no shock whatever. We decided to help a party who were coming up the mountain, as soon as I stepped outside the door I felt half dazed, and it took me a few seconds to realise what was happening. I was conscious of a violent pricking in my head as of lots of needles, only less painful. Our ice axes were discharging electricity and hissing hard, and so was the hut and most of the neighbouring rocks ; it was unsafe to lift one's arm or even a finger, as a sharp pain was felt in it at once, and as each lightning stroke fell on the hut, which was not 100 yards from us, we got a pretty violent shock, which made us start and catch our breath, but otherwise did no harm. We carefully held our axes by the middle of the wood, but one of the party when five yards from the hut leaned on his axe, and was immediately knocked down, so we left our axes, and on entering the hut again felt nothing, which was a more conclusive ♦"Meteors," Zeitschr., 1901. 97a modern lightning CONDUCTORS. proof of the protective effect of the copper sheathing than any of Faraday's well known experiments." THE MAGNETIC EFFECTS OF LIGHTNING. * Professor Platania also made some interesting experiments in 1906, and noted strong magnetic effects where lightning had struck some houses near Catania constructed of lava blocks from Etna and of brick. In one observation the fragments of a telephone wire of galvanised iron which had been struck acquired magnetic polarity ; for instance, taking a piece of wire fused at one end and cut at the other, the latter attracted almost equally the north and south poles of the needle, while the fused end if placed near the north pole pushed it back 5 degrees ; another piece fused at both ends caused the needle to deviate 20 degrees. The earth wire of the telephone ran down the face of a wall, and strong magnetic polarity was shown by the compass when it was held about six inches from the wall, the needle swinging right round. In another observation, although he did not find the wall so affected, at a distance of four yards from the conductor there was sensible deviation of the magnetic needle. One of the most common effects of lightning on watches is the magnetisation to which the various pieces of steel are subjected. In one case the balance had its poles so well defined, that when placed on a piece of wood and floated in water, it acted in a similar manner to a compass needle. The author mentions at page 36 that he had also found iron in a building which had been struck to have been partially magnetised. *Memorie clella Classe di Scienza Academia degli Zelanti, Vol. IV. 91 CHAPTER IX. FULGURITES AND OTHER VAGARIES OF LIGHTNING. SUNDRY NOTES. [ULGURITES, lightning tubes, or ceraunic sinters (Fr. fulgurites, pierres foudroy^es ; Ger. Fulguriten, Blitz- rohren, Blitzsinter), as their name implies, are fused tubes or other fused structures, produced in sand, earth, or in rocks, by the action of lightning. They seem to have been first noticed by Pastor Hermann, of Massel, Silesia, in 171 1, who, however, erred as to their origin, since he considered them a kind of fossil. It was, notwithstanding, early known that lightning causes fusion, as the papers of de Fischer, Buchholz, Tillet and Desmarest, and AUeon Dulae indicate ; and, in his papers on lightning and lightning conductors, Reimarus mentions that the points of con- ductors occasionally melted during storms. In his Alpine travels betv^een 1768 and 1789, Saussure found small blackish beads on the face of some slaty hornblende on the Dome de Gout6, obviously produced by the action of lightning. The directness of the evidence as to the origin of fulgurites is, perhaps, best illustrated in the account given by Withering in 1790, published in the Phil. Trans, of the Royal Society. On 3rd September, 1789, a tree was struck by lightning and a man who had taken refuge thereunder was killed. At the point of his walking-stick a perforation, 2J inches in diameter and 5 inches in depth, marked the place where the flash entered the ground. On digging, the soil was observed to be blackened for 10 inches more ; 2 inches deeper again melted quartzose appeared, and continued in a sloping direction for 18 inches, the fused material having run down the tube formed. 92 MODERN LIGHTNING CONDUCTORS. " The fulgurites from the Kensington sandhills, New South Wales, present no new feature as regards their form or general character. Externally they are rough, some- what whiter than the surrounding sand ; inside they are enamel-like, from the glassy surface of the fused silica. Under the microscope the fused ma- terial is seen to be full of small vesicles ; the sur- rounding sand fu.sed in the oxyhydrogen jet presents an almost identical appear- ance. In chemical com- position the fulgurites are substantially the^ same as the surrounding sand. "Unfortunately, too great a mass of sand would have had to be moved to reach the terminals of the tubes. After following one for a length of lO feet along its course, there appeared no indication of a change in size, and further exca- vation was impracticable."— Fig. 73. J. W. Grimshaw, M.I.C.E. The photograph, Fig. •]->,, exact size, gives a definite idea of the appearance and characteristics of fulgurites formed in loose sand. The Brighton Seashore Electric Railway. Magnus Volk, M.I.E.E., 1900. — The overhead wire was struck some distance away from the car, the current went to earth by the trolley pole of the car, and opened a 200 ampere automatic switch at end of the line with a loud explosion. At Labuan, Borneo, a doctor was dining, when a flash on the roof jumped to the lamp and thence to table, through the table VAGARIES OF LIGHTNING. 93 cloth and table down to earth. The cruet was fused, also knives and spoons. There was no appearance of any burning. Side flash from a tree, Stilland Farm, ShilHnglee, Sussex, January, 1904. Observer : Admiral J. P. Maclear. — Poplar tree was struck about 25. feet from the farmhouse, and at the same time the angle of roof received a stroke which passed down the rain- water pipe and portion of the discharge entered the lower room, passing by a moulding which was covered with gold leaf; much glass broken, front door forced open inwards. Note. — The tree acted as a conductor, and the oscillatory discharge affected the building. Upward effect of lightning, Garthersburg, Mo., U.S.A., June, 1902. Observer: S. A. Lehman. — Oak tree about 30 feet from house ; piece about 70 feet long, weighing about 70 lbs., was thrown upwards at an angle of 35 degrees through the house. No marks on tree above place where slab was torn off; house not struck. Inductive condenser discharge, June, 1894. — Several men were working in the United States Navy Yard at Norfolk, and during a storm had taken shelter under the iron hull of the Raleigh. There was no flash of lightning, and the officers on deck felt nothing, but the men were killed. Linesman upon the telegraph wires at Shrewsbury was fearfully hurt on a fine evening by a storm raging 50 miles away at Hereford. — C. E. Spagnolletti, M.LE.E., 1890. A similar case was reported from Russia in 1 894 ; the storm was 70 miles distant. Lightning strikes a railway carriage, July, 1900. Observer : W. Langdon, Past President, Institution Electrical Engineers. — The carriage was standing in a light timber shed at Derby, having some twelves lines of rails running through it ; it was standing on the second line from the wall which forms one side of the shed, and was one of fourteen. All the carriages are alike and are fitted with gas, having a gas pipe nearly the whole length of the top of each leading down to a gas reservoir fixed under the framework. The stroke, which showed no trace of passing through the shed, struck the gas pipe on the top of the carriage, made a clear hole of about J inch diameter in the pipe, and ignited the gas. Note. — This was probably a side' flash of great intensity from a B discharge to the adjoining rails outside the shed. It must have passed through the shed, but made such a small hole that it would be difficult to locate it. 94 MODERN LIGHTNING CONDUCTORS. A barn filled with hay was struck, but instead of the flash passing outside it went to earth through the hay, burning a large hole all the way down. — Paisley, Canada, 1902. Curious freaks, New York, August, 1904 — The flagstaffs on the Post Office, Tammany Hall, and the Flat Iron building, were struck, splintered, and hurled in fragments into the streets. Long flashes of lightning played from the rails of the Elevated Railway, and some woodwork was ignited. See page 82. Mypthyr Tydfil Waterworks. Cracking of cast iron plates. Observer: George F. Deacon, M.I.C;E. — In the dam used for impounding water was a vertical recess 50 feet long by 5 feet wide. The face was closed by ribbed cast- iron plates about f inch in thick- ness, see Fig. 74. The plates were loose in the brickwork, and the pressure oi water was equal on both sides. In December, 1902, the water was drawndown, when the whole of the plates for 33 feet from the bottom were F'G- 74- r J i. u '^ found to be cracked. The highest valve plate, shown by line on Fig. 74, was star cracked, and from out of the crack on this plate the main crack passed for 30 feet downwards through all the plates and flanges, and .several large masses had fallen away. The iron was tested by Professor Unwin VAGARIES OF LIGHTNING. 95 and found to be above the average strength. A thunderstorm was recorded at the works about the time the accident probably occurred ; the tower above was not then fitted with a lightning conductor. The case was submitted to Sir Oliver Lodge, who reported as follows : — " I do not think the hypothesis of a lightning shock is utenable. A spark taking place under water breaks it or throws it asunder with great violence, producing a real explosion, so that even a small spark under water can shatter an open tumbler in which the water is, and I have strained a copper vessel by taking sparks inside it when full of water. I think, there- fore, that a flash of lightning taking earth through water would be quite competent to smash the iron in the way described." Explosion of a sugar boiler at Liverpool. Observer : Sir Oliver Lodge, F.R.S. — A syrup boiler exploded, killing a workman. A pipe from the roof entered the boilers through a fairly insulated washer into the interior, and dipped below the liquid nearly down to the bottom of the vessel. It was thought that lightning entering the pipe from the roof produced the explosion. New York, August, 1904. — During a storm a steel chimney of the Smith Varnish Works on Long Island was struck and a tank of varnish exploded. The works were destroyed. SUNDRY NOTES ON LIGHTNING. Explosive action of Lightning, R. A. West, Nature, November, 1903. — " A cedar tree, 50 feet high, stood at a distance considerably less than its own height from a house at Englefield Green. The tree was struck, about 15 feet of the top was broken off, and the main portion of the trunk to about 4 feet from the ground was split in two. At the same time, an auracaria about 30 feet from the cedar was beaten down by a flash accompanied by much noise like pistol cracks, and a cloud of steam rose from the lawn on which the trees stood." Note. — It is probable that what was seen in the auracaria was the reflection of the flash that struck the cedar, and the steam emanated from the cedar, which was said to be of vigorous growth and full of sap. There is nothing to indicate an explosive effect in this case. — Author. " Balloon on leaving earth ceases to be charged electrically, as if a small portion of the earth." — Standard, 1900. Captive balloon struck at Augsburg, at an altitude of about 1,000 feet. Aeronaut saved, but men holding rope were rendered unconscious. — 1 902 . 96 MODERN LIGHTNING CONDUCTORS. Bell-ringing and stormsi — " The poor believe that this pious exercise dispersed the evil spirits of the storm, while the better sort said that it caused some kind of undulation in the air and broke the continuity of the electric fluid." — " Edward's Untrodden Peaks, &c.," Routledge, 1893. The following monkish rhyme was inscribed on mediaeval bells. — " Funera plango, Fulgura frango, Sabbato pango, Encito lentos, Dissipo ventos, Paco cruentos." The bells of Dawlish Church were rung during the storm, in the belief that the spirit of the bells would overcome the spirit of the lightning. — 1901. The bells at the village of Palan Perpignan were being rung by some children to avert a storm when the belfry was struck and four of the children were killed. — 1901. Bees are said to foretell a storm by leaving their hives and flying about the entrances. Beehive revealed by lightning which struck tree. — Grove Mill, Hitchin, 1900. Bicycle struck near Taunton. The rider was pushing it by the saddle when the lightning struck the handle bars and twisted the framework out of shape. — 1902. " Crosses are often erected in Piedmont on hay and corn ricks to protect them from fire and lightning. Sometimes they are placed over stables to ward off robbers. In fact the sacred symbol is really regarded by the country folk in much the same light as the insurance company's plate which is affixed to buildings on the Continent, with the advantage too of being free from any premium." — Eustace R. Ball. St. Elmo's Fire. — "In modern times, around the Medi- terranean, these electrical displays have been hailed as the light of St. Clair, St. Nicolas, St. Helena ; elsewhere they have had the appellation St. Barbe and St. Elmo. The Portuguese call them Corpo Santo, and the English, Comazants or Corposants. Even at the present day of enlightenment, sailors attach a certain importance to these signs ; for they suppose that the apparition of one of these natural lights portends that the severest part of the storm has yet to come, while two of them at once indicate a cessation of the tempest. In all of this we trace an inheritance from antiquity ; Pliny, in fact, telling us that these lights are dangerous SUNDRY NOTES. 97 and unlucky when coming alone, but that when two come together they bring comfort and foretell a prosperous voyage and chase away that ' dreadful, cursed, and threatening meteor, Hellena.' Thereupon, men at sea invocated the gods Castor and Pollux."* The captain of the British ship Mohican reported that on approaching the American coast, the iron ship entered what is described as a magnetic cloud, and became charged with electricit3^ " Lambent flames played here and there, the compass was deranged, and the crew felt the sensation of being electrified. "t Note. — St. Elmo's Fire is usually in the form of a brush or star of light on the top of a mast or anything pointed. It is not unknown here, and has been seen at Ben Nevis observatory eleven times in four years. Another variety has often been noticed by Alpine climbers. The late Professor J. D. Forbes, while walking on a glacier, heard a rustling noise come from his alpenstock. He raised his hands, whereupon his fingers fizzed ; he inferred, therefore, that they were so near a thundercloud as to be electrified by induction. The phenomena are observed to cease, as a rule, after each peal of thunder, but they are quickly renewed, and at each discharge shocks more or less strong are felt. Dr. Werner von Siemens, the noted physicist, while on the top of the pyramid of Cheops at Ghizeh during a storm, perceived that a flow of electricity escaped from his finger when extended towards the heavens. The current manifested itself powerfully enough to cause a hissing noise, and from the metal button of his guard he obtained electric sparks. " The dry cold of the winter in Manitoba, according to Professor Bullet, of Winnipeg, is attended by manifestations of electricity. By sliding the feet on the carpet one can electrify the body so that a finger yields a spark and ignites a gas jet. This effect, however, can be produced in many parts of America. One writer says that after electrifying his hand he attracted to it the filament of an incandescent lamp." — Globe, M.a.y 5th, 1905. GLOBULAR LIGHTNING. This, although imitated in the laboratory by Plant6 and others, still puzzles us a good deal. There are many authenticated instances of the phenomenon. Count G. Hamilton records that at his house on the shores of Lake Wener, twenty seconds after a very vivid flash, a brilliant white ball was seen over the dining table, which disappeared almost immediately with an explosion. " At Nieheim, in Westphalia, six people saw a ball of fire descend in a house which was burnt to the ground." — Engineering, June, 1902. '■' " Pre-scientific Electricity."— Hayden. t Standard, August, 1904. 98 MODERN LIGHTNING CONDUCTORS. Mr. Perry F. Nursey, C.E., gave an interesting account in the Morning Post, August Sth, 1904, of globular lightning which fell in the Buckingham Palace Road, and more recently Mr. C. S. Northcote, M.I.E.E., writing to the Electrical Review, May, 1905, states "that he distinctly saw a ball of fire descend during the recent storm, at about the time St. Mathias Church, Richmond, was struck." "An account from Milan, 1841, states that a globe of lightning moved so slowly over a street that spectators followed in its rear, watching its final dissolution on contact with a church spire. "On February 4th, 1863, when Nelson's monument on Calton Hill, Edinburgh, was struck, the lightning appeared under the influence of powerful air currents, being driven forward with a rapid motion. Another report from Paris states that a globe of lightning was visible descending from the sky, and equal in size to the full moon. On bursting, vivid zig-zag flashes were visible, and a hole the size of a cannon-ball was rent in a neighbouring house. Globular lightning, as reported to have been seen in the Glendowan Mountains, in county Donegal, was remarkable. A ball of fire was visible for twenty minutes. When first seen, its estimated size was 2 feet in diameter, and of a bright red hue ; on disappearing, it had shrunk to 3 inches in diameter. After numerous contacts with the soil in its passage, it entered a river bank, cutting a large trench through the peat to a considerable depth, ejecting the debris into the centre of the stream, and buried itself in the opposite bank." Another account, as seen by Dr. Tripe, on July nth, 1874, and contributed by him to the Meteorological Society, states, " that he saw, when looking due South during a very heavy thunderstorm, a large ball of fire rise up till it reached a height of about 45 degrees. when it started off towards the West with such remarkable rapidity as to produce the appearance of a flash of forked lightning, finally entering a dark cloud and disappearing." Curious effects.— "At yesterday's meeting of the Royal Meteorological Society the Rev. C. F. Box gave an account of some curious ' Effects of a Lightning Stroke at Earl's Fee, Bowers Gifford, Essex, April 13th, 1904.' A thunderstorm occurred during the early morning hours, and about 3 A.M. there was a blinding flash, lighting up the whole neighbourhood for miles around, followed immediately by a crashing explosion. One person stated that he saw what appeared to be a cylinder, and another person a ball of fire, descend and then explode, ' casting darts ' in all directions. On SUNDRY NOTES. 99 careful examination in daylight, it was found that in an oatfield, which had recently been dredged, there were three distinct sets of holes, ranging from 9 inches down to about i inch in diameter. The holes, which were circular, diminished in size as they went down- wards, and remained so on to the perfected rounded ends at the bottom. Upon digging sectionally into the soil, which is stiff yellow clay, it was found that the holes were ' as clean cut as though bored with an augur.' " Invoking lightning. — Methodist Minister, Strondesbury, Pennsylvania, said to have prayed that lightning might strike a brewery nearing completion. The brewery was struck and destroyed ; owner sued the pastor for damages. — 1900. Hats off to the lightning. — "You must take your hat off to the lightning in the South American town of Quito, unless you want to be guilty of very bad form," states Cassell's Saturday Journal. " There the lightning is deeply respected. Everyone removes his hat when it flashes, no matter if rain is falling ; and when the streets are busy and lightning is abundant, a grotesque effect is produced by these salutations, which seem to be regarded as a duty by all well-behaved persons." " A lightning rod was erected by a farmer in Russia, but when the peasants heard that it was used to divert the thunder- storms, they concluded that it had caused a drought from which they were suffering, so proceeded to demolish it." — Standard, 1905. The spectrum of lightning was photographed at Harvard U.S.A., in 1902. The spectrum varies, but many lines appear due to hydrogen, and it is curiously like that of the new star Perseus. Dark lightning. — " Watching a thunderstorm with brilliant flashes, I was surprised to see with great vividness two nearly vertical lines of darkness on a suddenly illuminated sky, each having the jagged appearance of lightning. I remember to have seen two real flashes of just the same shape and relative positions, and concluded that the black flashes were due to their residual influence on the retina. Turning my eyes quickly to an illumi- nated wall inside the house I again saw the same double dark flash." — Lord Kelvin, Nature, 1901. Lightning-struck houses not rebuilt. — " Valerius Publicola had his house on the Palatine destroyed, and he built a new one on the site, but the Quirites objected to anyone 100 MODERN LIGHTNING CONDUCTORS. building on a spot consecrated by Jupiter's sacred fire, so he had to pull it down." — " Pictures of Old Rome," Frances Elliot. Lightning conductors, Egyptian. — " Flagstaff's in front of palaces and temples were surmounted with yellow metal spikes made of an alloy, and the pole was partly covered with a thin foil of the same metal. A priest discovered that this would protect the building from the fiery thunderbolt of Typhon."^-H. B. Proctor, 1898. Roman superstition. — " Artaxerxes believed that two swords, planted in the ground, dispersed the thunderclouds. In the time of Charlemagne, poles were used for the same purpose, but, unfortunately for those that would deprive Franklin of scientific renown, they were not supposed to have any efficacy until bits of magical paper had been stuck upon them. " The ancients also believed that lightning never fell except by the immediate interposition of the gods ; and whatever thing or place it struck was ever after deemed sacred — consecrated by the deity himself. The Greeks placed an urn over the spot where the lightning entered the earth, and the Romans had a similar observ- ance. Herodotus tells us that when Scyles, who had studied the language and sciences of Greece, ascended the Scythian throne, it was his desire to be initiated into the mysteries of Bacchus, which was against the wish of his people ; and as he was about to take some of the sacred utensils in his hands, his palace in the city of Borysthenites was totally demolished by a thunderbolt. " To imitate thunder and lightning was considered a sacrilege by all religions. There is an exciting passage in Virgil, wherein the poet describes the infernal regions and the fate of Salmoneus. This prince, according to the legend, wished to be called a god, and to receive divine honors from his subjects. Therefore, to imitate thunder, he used to drive his chariot over a brazen bridge ; and to counterfeit lightning, he darted torches on every side. This impiety provoked Jupiter. Salmoneus was struck by a thunder- bolt, and placed in the infernal regions near his brother Sisyphus." — " Pre-scientific Electricity," R. Hayden. " Curiously enough, the ancients do not appear to have represented the actual flash, but have made thunder and lightning an attribute of the gods ; thus Jove's thunderbolts are often mentioned and usually depicted by the old masters as darts held in the hand ready to be hurled. SUNDRY NOTES. 101 " At the Dorrien Palace, Genoa, instead of these being of the usual form, they are more like rods surrounded throughout their length with lambent tongues of fire. In the time of the Romans lightning was much observed in augury, and was a good or bad omen according to the circumstances attending it. Persons killed by lightning, being thought hateful to the gods, were buried apart by themselves lest the ashes of other men should receive polution from them. It is said that they were generally buried where they fell, probably from the reason now universally accepted that decomposition sets in very quickly in the bodies of those killed by lightning, even preventing in case of sheep or oxen, their carcasses being dressed for market. The Romans had also the good sense to avoid places struck by lightning, which were often fenced in so that no one could use the houses on which Jove had set the mark of his displeasure. To this day the same buildings are struck from time to time, and certain localities are visited by thunderstorms more than others ; this knowledge is taken advantage of by the witch- doctors of South Africa, who are said to stand fearlessly on a certain spot during a terrific storm." — " Protection from Lightning," R.I.B.A., K. Hedges, 1900. Lightning in a clear sky. — This is said to be common in San Domingo. — U.S. Weather Bureau, 1901. Long lightning conductor. — The top is some distance above the meteorological station on the Zugspitze, Germany. It continues down the side of the mountain to a body of water; the length of the rod is three and a half miles. Remedy against lightning. — " The Abyssinians have great dread of lightning, and an Italian doctor, having injected ether into a man insensible through a stroke, ether is now considered a ' remedy against lightning.' " — Pall Mall, October, 1901. Measuring a flash. — "A picture was taken from a window of the Hamburg ob.servatory which included a building and the flash that struck the building at the moment of uncovering the lens. It was therefore calculated that this particular flash was 5 mm., or one- fifth of an inch, across." — Chambers' Journal, August, 1901. " Passing between two earth plates buried in ground 60 feet apart, the resistance of the earth should not be more than an equivalent resistance which would allow a current of two amperes at four volts." — Trotter, 1901. 102 MODERN LIGHTNING CONDUCTORS. " One hears a great deal of the intensity of a Hghtning stroke, and various surmises have been made as to the number of volts required to cause a flash to leave the clouds and dart through the atmosphere — a medium which is of such high resistance that with the most powerful electric currents that are in general use, i foot of air space is considered perfect insulation. On this subject we have the interesting experiments of Sir William Preece with the Warren de la Rue battery, which were published in the British Association report of 1880, and more recently the experiment of Prof. John Trowbridge (published last year) with 150 plate-glass con- densers, 1 8 inches by 20 inches, \ inch thick, charged to 20,000 volts by means of 10,000 Plants cells. The professor has since increased the charge to 42,000 volts, and by use of Leyden jars he has obtained a pressure estimated at 2,000,000 volts. He remarks : ' I cannot go higher for the interesting reason that air at atmospheric pressure becomes a fairly good conductor beyond 2,000,000 volts, and it is impossible to charge Leyden jars to this potential or to produce sparks in a laboratory of greater length than 7 feet. To obtain the manifestations of 3,000,000 volts it would be necessary to put the apparatus in an open field, at least 30 feet from the ground, and remote from all other objects. Jars and circuits charged for this high voltage emit a luminous discharge to the floor of the room and to the brick walls, and indicate by this inductive discharge the presence of steam pipes 20 feet distant. The air breaks down quickly under this powerful electrical stress, and behaves like a rarefied gas.'* " It is well known that lightning shatters stone and pulverises the finest growth of the forest, and this must be due to the quantity of the electric discharge, which has for some extraordinary reason been greatly underestimated. Herr Pockels has devised an ingenious arrangement for measuring the currents that pass through a lightning conductor by testing the residual magnetism in bars of basalt, which were placed cross-wise near a lightning conductor and tested after a lightning discharge had passed. On examination of two bars thus exposed at the observation tower on Mont Cimone in the Appenines, it was inferred that the currents were respectively 10,200 and 5,330 amperes. It was held that the maximum current ♦ The difference of potential for a spark a mile long between flat plates is roughly 16,000,000 electro-static units, each one of which is equal to 300 volts, that is, nearly 5,000 million volts. — Lodge. SUNDRY NOTES. 103 which has passed by or through the lightning rods was quite double these figures, as the bars were not tested till several months after the lightning discharge, and had in the meantime suffered vibration, which would partially demagnetise them." — " Protection from Lightning," British Association, K. Hedges, 1901. Lightning tree. — The oak has thus been so called in "As You Like It.'' Celia, speaking of Orlando, says, " I found him under a tree like a dropped acorn." Rosalind rejoins, " It may well be called Jove's tree, when it brings forth such fruit." "The wood of trees struck by lightning are not burnt by the Kentucky negro, for fear that his house will burn if struck." — Journal of American Folk Lore. Circular action. — A ribbon of bark on a fir tree near Forenville was stripped from the trunk in a spiral line of almost mathematical regularity.— 1903. Rifles strucic. — " Eighteen soldiers were sleeping in a bell tent with their eighteen rifles stacked against the centre pole. The flash divided among the rifles and killed all the men." — H. S. Carhart, American Electrician. Liner strucit) December, 1903. — The Teutonic was struck in a snowstorm, when 200 miles east of Newfoundland. The masts are of hollow steel, except for the tops, which for a distance of 13 feet are of wood. The lightning splintered the wooden top, and the rope halliards used to hoist flags were rolled up like a ball and driven through the opening. The thunder flower. — " The stonecrop is known in the lake district by this name, and in old times was planted on farm- houses to protect them from thunderstorms." — The Garden, 1901. Naphtha set on fire. Barge struck, unloading, Thames Haven ; also Gun-cotton exploded, Nobel's Works, Ardeer, Ayrshire. — This was probably caused by a side flash from the neighbouring wires, which were struck. — K. Hedges, observer, 1900. Altar of church at Els, South Austria, set on fire. — 1900. Hot Spring at Amarron saltfields, Indian territory, U.S.A. (about 20 feet by 60 feet), was struck and said to have been set on fire, and continued to burn for some time. — 1901. (Probably a petroleum spring. — AUTHOR.) 104 MODERN LIGHTNING CONDUCTORS. The Pernod Distillery at Portarlier was struck and destroyed. The flash, conducted by the electric light wires, set fire to the alcohol in the cellars and 600,000 gallons were destroyed. — August, 1 90 1. Upward motion stroke. — " There is no reason to doubt that the discharge sometimes takes place from earth to cloud. That is to say, that while we now consider a lightning flash as something like the discharge of a condenser through its own dielectric, made up of excessively frequent alternations — say, something like 300,000 times per second — the spark, or core of incandescent air, may seem to have its beginning at the earth's surface, that is to say, the air gap breaks down first at a point near the earth." — McAdie and Henry, Washington, 1899. Velocity of storms.— W. A. Eady, of U.S.A., observed that the actual thunderstorm had a velocity at the height of three quarters of a mile of more than double that of the velocity one hour in advance of the storm. He also noted a circular draught of air, proving that thunderstorms have a slight rotary motion. — 1901. William Maine's account of the effects of lightning on his rod| dated at Indian Land, in South Carolina, August 28th, 1760: — " I had a set of electrical points consisting of three prongs of large brass wire tipt with silver, and perfectly sharp, each about 7 inches long ; these were riveted at equal distances into an iron nut, about three- quarters of an inch square, and opened at top equally to the distance of 6 or 7 inches from point to point, in a regular triangle. This nut was screwed very tight on the top of an iron rod of above half-an-inch diameter, or the thickness of a common curtain rod, composed of several joints, annexed by hooks turned at the end at each joint, and the whole fixed to the chimney of my house by iron staples. The points were elevated 6 or 7 inches above the top of the chimney, and the lower joint sunk 3 feet in the earth, in a perpendicular direction. " Thus stood the points on Tuesday last about five in the evening, when the lightning broke with a violent explosion on the chimney, cut the rod square off just under the nut, and I am persuaded, melted the points nut, and top of the rod entirely up ; as after the most diligent search nothing of either was found and the top of the remaining rod was cased over with a congealed solder. The lightning ran down the rod, starting almost all the staples and unhooking the joints without affecting the rod, except on the inside of each hook where the joints were coupled, the surface of which was melted and left as cased over with solder. No part of the chimney was damaged only at the foundation where it was torn out. Considerable EXTRACT FROM FRANKLIN ON LIGHTNING RODS. 105 cavities were made in the earth quite round and several bricks were torn out. It also shattered the bottom weather-board at one corner of the house, and made a large hole in the earth by the corner post. On the other side of the chimney it ploughed up several furrows in the earth, some yards in length. It ran down the inside of the chimney carrying only soot with it ; and filled the whole house with its smoke and dust. It tore up the earth in several places and broke some pieces of china in the beaufet. A copper tea-kettle standing in the chimney was beat together, as if some great weight had fallen upon it, and three holes each about half-an-inch diameter, melted through the bottom. What seems to me most surprising is, that the hearth under the kettle was not hurt, yet the bottom of the kettle was drove inward, as if the lightning proceeded from under it upwards, and the cover was thrown to the middle of the floor. The fire-dogs, an iron loggerhead, an Indian pot, an earthen cup, and a cat were all in the chimney at the time unhurt, though great part of the hearth was torn up. My wife's sister, two children and a negro wench, were all who happened to be in the house at the time. The first, and one child, sat within 5 feet of the chimney, and were so stunned that they never saw the lightning nor heard the explosion : the wench with the other child in her arms, sitting at a greater distance, was sensible of both \ though everyone was so stunned that they did not recover for some time ; however it pleased God that no further mischief ensued." ■H Benjamin Franklin on lightning rods, Letter LIX., Paris, 1767 : — "It is therefore that we elevate the upper end of the rod six or eight feet above the highest part of the building, tapering it gradually to a fine sharp point, which is gilt to prevent rusting. Thus the pointed rod either prevents a stroke from the cloud, or, if a stroke is made, conducts it to the earth with safety to the building." 106 USEFUL NOTES. ""WEIGHTS OF COPPER STRANDED GABLE (Consisting of seven wires twisted together). Weights per ) f-in. ^-in. f-in. f-in. |-in. diameter. 6 ozs. 10 ozs. 15| ozs. 22| ozs. 30f ozs. foot, about : GOPPER, TAPE OR FLAT BAND. Weights per foot, about ; f I X ^ in. 6 ozs. 9 ozs. 1 X ^ in. 8 ozs. 1 X /,- in. 12 ozs. li X J in. 10 ozs. li X tV in 15 ozs. IJx^in. 12 ozs. 2 X ^ in. 15-46 ozs. 14: TS' 2xA in. 18 ozs. 2319 ozs. • Furnished by Frederick Smith & Co., Salford. SOLID ROD. Weights per ( \-\a.. A'™- f-i'^- diameter- 4J ozs. 7 ozs. foot, about : ; 3 ozs, Copper weighs '321 lbs. per cubic inch, or 555 lbs. per cubic foot, and has a specific gravity of 8'912 at 60° Fah. Tensile strength of hand-drawn wire is 22 to 28 tons per square inch section. IRON WIRE STRANDED GABLE (Consisting of seven strands). Weights per ( %j^ j j^ ^.^_ fathom of -^ ** ^ " 6 feet, about : (. 1'7 lbs. 2-25 lbs. 4-5 lbs. f-in. diameter. 6-2 lbs. Id. pep lb. - £9 6 8 per ton. Ad. „ = 4 13 4 „ Id. = 268 TABLE OF CONDUCTORS IN ORDER OF CONDUCTIVITY. Silver. Copper. Gold. Aluminium. Zinc. Iron. Lead. Charcoal. Those substances which allow electricity to flow through them are called Conductors, and those which do not are called Insulators. Ampere IVIeter. — An instrument used for measuring strength of current. Earth. — A conductor is said to be "earthed" when it is so arranged that it makes good electrical connection with the ground. Ohm. — The unit of resistance. Resistance. — The opposition presented by the circuit to the flow of current in it. io6a HISTORICAL SUMMARY. 1717. Reiman, a Pole, saw lightning run along iron rods without injuring them, but shattering stone between. 1751. Franklin's kite experiments. 1752. De Lor de Buffon erects an iron pole 99 feet high mounted on a cake of resin. ,, Franklin — He makes known the action of lightning rods. 1753. „ He erects the first conductor. ,, Richmann killed at St. Petersburg by a stroke from his insulated vertical rod. 1767. Franklin's conductors erected at St. Paul's Cathedral. * 1771. The controversy of knobs instead of points for conductors and the matter referred to George HI.* Franklin was then fighting against the crown. 1820. Application of Lightning Conductors to ships by Snow Harris. 1876. Clerk Maxwell on the Protection of Buildings from Lightning. Paper read before the British Association. 1878. Conference of learned societies. 1881. The Lightning Rod Conference Report published. 1884. Paper read at the Royal Institute of British Architects by Col. the Hon. A. Parnell on the action of lightning strokes. 1888. Oliver Lodge delivered the Dr. Mann Lectures at the Society of Arts. ,, Joint discussion of Sections A and G at the Bath meeting of the British Association. * There is some uncertainty as to the exact date, a portion of the original iron conductor, can be seen at the Victoria & Albert Museum. — Author. 1889. Paper read by Oliver Lodge on Lightning, Lightning Conductors and Protectors. Institute Electrical Engineers. 1899. U. S. Department of Agriculture. Weather Bureau. Lightning and Electricity in the Air. 1900. Paper read by Killingworth Hedges on the Protection of Buildings from Lightning, at the Royal Institute of British Architects, describing his re-arrangement of Lightning Conductors at St. Paul's Cathedral. 1901. The Lightning Research Committee initiated by Killing- worth Hedges. A paper read at the Glasgow meeting of the British Association. 1902. A system of Conductors designed for Westminster Abbey. 1904. The action of Lightning strokes on Buildings. Hedges. British Association Meeting, Cambridge. 1905. April loth. The Lightning Research Committee's Report published. 1910. Phoenix Assurance Company's Rules drafted by Sir Oliver Lodge, Killingworth Hedges, and Castle Russell. * POINTS OR KNOBS. "While you, great George, for knowledge hunt, And sharp conductors change for blunt, The nation's out of joint ; Franklin a wiser course pursues, And all your thunder useless views By keeping to the point." MEMORANDA. 107 INDEX. PAGE Abyssinians — Dread of lightning by . . loi Admiralty— Cone theory . . . -13 Rules for protection of, struc- tures 13 Suggestions for testing . . 36 Agricultural Objects — Barn, protection . 94 Cattle ... .49 Protection of . . 55i S6 In America 49 (See Farm Buildings.) Aigrettes — Method of fixing points . 24,26 On ridge of roof with down conductor . 23 St. Paul's Cathedral . . 34 Use of . 15,22,25,40,41,45,56 Ainsworths Mill, Lancaster — Effect of lightning on . 68, 69 Air Terminals 21,22,25,28,42,48 (See also Terminals.) Alcohol— Ignited by lightning . . 104 Alexandra Hotel, Darwen — Effect of lightning on . 60 All Saints' Church, Bramham, YORKS — Effect of lightning on . -78 All Saints' Church, Maiden- head — Effect of lightning on . 64, 65 America— Agricultural system of protec- tion . . 49 Building construction in . 39, 40 Methods of protection from lightning in . . 48, 49 page America — continued. Reports on damage by lightning in 49 Appendix A— Analysis of L.R.C. Observers' Reports on buildings fur- nished with conductors . 86 Arched Coronal for High Chimney . • ■ 3° Architects— Royal Institution of British, on lightning ... 2 Armoury — Struck by lightning . . 82, 83 Austria— Methods of protection in . 56 95 14, 71 . 9. 10, 28 94 Balloon— Struck by lightning . Balusters — Method of protection Barbed Iron Wire — Protection by . Barn (Hay) — Effect of lightning on Bees — Effect of approaching storm on 96 Belgium — Hotel de Ville, Brussels, pro- tection of . . . .56 Bells— Effect of lightning on . 82 Monkish rhyme on . . 96 Protection of . . 18, 45 Superstition as to bell-ringing . 96 ■ Berlin Electric Technical Association— Committee of . . -So Recommendation of . . 2 INDEX. 109 PAGE Bezold, Dr. Von — On extent of damage by light- ning 88 Bicycle — Struck by lightning . . .96 Birmingham School of Art — Struck by lightning. . -85 Bonded Joint for Rain-water Pipes . . . . 29 Boston (U.S.A.)— Cadet Armoury at, struck by lightning . . .82, 83 Bournemouth^ Chimneys at Upper Parkstone, struck by lightning . . 78 Box, Rev. C. F.— On effect of lightning stroke . 98 Box T Joint . 24, 25, 30, 42, 44 (See Joints.) Boxes (Connecting) . . 24, 25 Bird-cage (see Cage Protection). 27 Brewery — Struck by lightning . . -63 Bridge of Weir Gasworks, Renfrewshire — Effects of lightning on . .81 Brighton Seashore Electric Railway — Overhead wire struck by light- ning . . -92 British Association— Discussion on " Protection from Lightning" at . 102, 103 Brussels — Hotel de Ville, method of pro- tection at . . . 51 Buchholz . . . .91 Bullet, Professor — On electrical effects of dry cold weather . . .97 Burial — Roman use of, after lightning stroke . loi Cage (Bird) System— Clerk Maxwell's . 9, 27 Described . . -53, 56 Explosives, use of, for pro- tecting 47 Faraday's . 55 Ideal .... 27 page Cage ^Bird) System — continued. Lightning Research Com- mittee's Report on . 7, 27 Modified system . . 45 Protection . . 46, 53 Testing . . . . 34 Camberley — Cottages at, struck by lightning Sewer ventilating shaft struck by lightning at Carbon, pulverised — Use of, in earth connection . Cattle — Damage to ... . Cavendish Laboratory (Cam- bridge) — Struck by lightning . "Chambers' Journal'' — On lightning and trees Charcoal — Use of, in earth connection 31, 44, 45 Charlemagne — Lightning conductors in time of 100 Chatham — Effect of lightning on shop at . 79 Chimneys— Arched coronal for . . . 30 Earth connection . -Si Effect of lightning on 29, 37, 60, 61, 63, 78, 81 Protection of 7, 8, 17, 29, 51, 68, 79 79 78 31 49 90 35, 66 Steel . 95 Churches— Altar destioyed. 103 Bells of . 45 Clocks in towers of 45 Damage to 68 Down conductors 23 Insurance of 87 Iron wire conductor for 27 Protection of . 22, 23, 39, 43, 44, 45 68 Spire on towers . 8 21 43 45, 64,65,66,72,74, 85 Struck by lightning . 14, 60, 64, 65, 66, 68, 69, 70, 71, 72, 73, 74, 76, 85 Vanes on . . . 31, 37, 43 Cicero i Cinders or Coke — Use of, in earth connection . 31 no INDEX. PAGE Circular Action of Lightning 103 Circular Bands . . 7 Cirencester Railway Station— Effect of lightning on . .77 Clamps— Use of 46 Clerk Maxwell— Cage protection by . . 9, 27 Clocks, Turret— Protection of . . . 18, 45 Coastguard Station Damaged BY Lightning . . .85 Coatbridge Church, Coat- bridge — Effect of lightning on . 14, 70, 71 Coke — Use of, in earth connection . 57 Collieries — Method of protection . . 20 Necessity for protection of head- gear 20 Cologne Cathedral — Method of protection at . -52 Comazants, or Corposants— Superstition as to . . .96 Conductor (s)— Absence of . . . 71, 87 Action of . . . .5 lightning on . 26, 37 Aigrettes (see Aigrettes) . -15 Cage (see Bird-cage system) . 27 Church spire . . -45 Collecting points . . -55 Condemned method of running 20 Connection of metal work with 53, 61, 63, 68 Connection, vertical and hori- zontal .'19,41,44,46,50,57,70 Connection with interior metal work 51 Connections with metal work . 86 Continuity of . . . .68 Contour without connecting points ... .55 Copper . 5, 41, 43, 50,51, 52, 54 (See Copper.) conductivity of . .17 Curves in . . . 23, 50, 55, 56 Distance from structure . . 73 PAGE Conductor (s) — continued. Down . . .23, 26, 28, 47 Dutch use of . . . .25 Earth connection in France . 53 Earth connection of 26, 31, 32, 53, 62, (See Earth Connection.) 64, 70 Earth plate, connection to cable . . . 32 Egyptian 100 Electrical resistance of . 53 Electro-plating. . . .16 Fastenings of . . 15, 16, 43, 57 First in Europe . . 2 Galvanised . . 42 Gauge . . . . 17, 54 Gilding . . .16 Horizontal . .15, 22, 28, 84 Imperfect earth . . 64 Independent earth . . .62 Installation, method of, in Hungary . . . -55 Insulation of . . 16, 71 Inter-connection of . . .70 Iron . 5,17,27,41,45,46,50,54 Joints (see Joints) . . .34 Leading inside structure . 72, 76 Looped 71 Long loi Measurement of current pass- ing 102 Materials for . . . .17 Number of 16, 22, 38, 39, 43, 45, 46, 62, 63, 64, 85, lOI Oscillation in copper . . . 70 Partial protection from B flash 6 Platinising 16 Pointed 8 Points of, melted by lightning . 91 Poplar trees as , .89 Protection from. . . -So Risk of fire . . . .53 Rules for erection of . . 15, 16, 17 Running, L.R.C. method . . 20 Running, method of . . 18, 23 Separate earth connection . 64 Single, use of . .17,61,63 Spratt's . . .72, 73 Subsidiary. 21,22,43,70 Tape. . . 17,34,76 Terminals, upper . . .16 Testing 34 Thatched roofs, for . . . 54 INDEX. Ill Conductor (s) — continued. Thickness of . Wet String . . . . (See also Lightning Rods.) Cone Theory . . 13 Contents Continental Methods of Protection Contractors — Conditions of tender by . Conductivity of Metals Conway — Dwelling-houses at, struck by lightning . . . . Copper — Air terminals . Bands Cable Conductors . .17, 43, Rods weight of PAGE • 54 ■ 5 14 vii 43 106 83 • 17 40, 41 54, 56 18 106 • 31 12, 27 . 26 Tape for earth connection Unsuitability of . 11, Wire connecting metal work Cost— Considerations as to, of pro- tection 38-47,50.51,53.54.56, 59, 71 Of copper . . . .106 Crosses— Superstition as to protection from fire and lightning by CUBBINGTON, WARWICKSHIRE— Damage from lightning at -83, Curves — Avoidance of . . 23, 50, / Effect of lightning on In rods .... 12. 96 56 55 18 Dark Lightning — Appearance of . . . -99 Dawlish — Bells rung at, to avert storm . 96 De Fischer — On lightning . . . .91 De l'Orme, Philibert . . i Desmarest — On lightning . . 91 Devaar Lighthouse — Effect of lightning on . -63 Distillery — Destroyed by lightning . .104 PAGE DiVISCH— Erects first Hghtning conductor 2 Double Cone of Charles . 13 DULAE — On lightning . . -91 Dutch Academy of Science . 52 Dutch Meteorological Insti- tution — Report on strokes affecting trees 89 Dwelling Houses — .Struck by lightning . 61, 65, 75, 76, 77,78,79,80,81,82,83,84 Earth Connection (s) 17,32,41, 42, 50, 54, 55, 56, 57, 59, 87 Basket . . • • 57 Chimneys . . . . .51 Clamps for testing 44 Electrical conductivity and . 32 Farm buildings . . . 46 Importance and necessity of 8, 9, 14 Independent 62 63 Lead roofs, from 68 Looping, undesirable in . 67 Metals of . 15 Method of . 19, 26, 31, 33, 66 67 Number of . 21,22,34,43, 44 67 Proximity to gas mains . 15 67 Testing 34 44 Tubular . . . .31, 33- 46 "Edward's Untrodden Peaks' — Reference to 95 Egyptian — Lightning conductors I, 100 Electric Light Wires— Conductivity of. 104 Protection of 72 Electric Railway— Struck by lightning . 92 Electrical Effects— Of cold . 97 Storms 96 Electrical Engineers— Institute of 3 Electricity — Atmospheric antiquitv of, stu iy of . . I Elektrotechnische Verein — On damages from lightning 14 Elevation Rods— For chimneys . 22 112 INDEX. Elevation "Rotis— continued. Flat roof, for . Sleeve connecting; points . PAGE I, 22, 27, 42, 57 Use of Explosives— Factory damaged by lightning 85, 103 Protection of . . .7, 56, 85 Report as to protection . . 47 Factories Protection of . . 12, 29, 46 Faraday's — Cage protection . . -55 Farm Buildings— American practice . . -49 Protection of . . 46, 48, 55 Specification for . . .46 Thatched roofs of . . 54 Fastenings — Conductor . . -43 Galvanised iron cleats . 41 Holdfasts . 24, 28, 42, 43, 44, 46 Straps (See Joints) . . 46 Festing, General— Report by .... 72 FiNDEISEN, BAURAT — Methods of protection . .51 FiNIALS — Protection of . . . 45, 64 Fire-balls 10 Flagstaffs — Effect of lightning on . -94 Protection of 39, 76, 78, 82, 83, 85 Use of, as conductors . . 100 Forbes, Professor J. D, — Electrical effects of thunder cloud 97 France — Methods of protection in use in 57 Frankfort— Municipal by-laws on lightning protection . . . .52 Franklin's System— Lightning rod . Use of, in Hungary Fulgurites :. 13. '05 55, 66 11,91,92 Galvanic Action— Copper and iron . 26, 42, 52 page Gas Pipes — Conductivity Effect of lightning on • 72, 73 33, 44, 79, 82,93 Proximity to conductors . 15, 67 Gas Works— Struck by lightning . . .81 Germany — Government inquiry as to lightning and trees . . 89 Insurance in Schleswig- Holstein .... 88 Practice in . . . 50-52 Glendowan Mountains, Ireland— Remarkable instance of globu- lar lightning on . . -98 Globular Lightning 10, 97, 98 GoDSHiLL Church, Isle of Wight — Effect of lightning on . . 74 Insurance of . . . -87 Golder's Green — Army Convalescent Hospital struck by lightning . .61 Gordon College, Aberdeen — Effect of lightning at . . 82 Greeks — Knowledge of atmospheric electricity . . . . i Superstition as to . . . 100 Greenfield, St. Mellons, Monmouth — Effect of lightning on dwelling houses at . . . .84 Greenhouses — Struck by hghtning . . .80 Grimshaw — On fulgurites . . . -92 GULIK, Dr. D. VAN— Report by, on protection from lightning . . . -52 Gun-cotton — Exploded by lightning . . 103 Protection of . . . .7 Gutters— Connection at . . . .46 (See also Rain-water Pipes.) Hamilton, Count G.— On globular lightning 97 INDEX. 113 PAGE Hanslope Church, Stoney Stratford — Effect of lightning on . 72, 76 Hayward's Heath, Sussex— Effect of lightning on villa at . 82 Heathfield, Sussex — Effect of hghtning on house at . 65 Hermann, Pastor — On fulgurites . . . .91 Herodotus — On thunderbolts . . . 100 Hertz — Work of 55 Hess — On trees 89 Holdfasts — For cable . . 24, 42, 43, 44, 46 on wall , 28 Holland — Conductors used in • • 53 Insurance in Practice in Ho6r, Dr. Moritz von Hopkinson, Thomas . Hotel de Ville, Brussels — Struck by lightning . System of protection Hungary — Practice in . . -56 Reports from . . .8 Illustrations, List of . . viii Inductive Condenser Dis- charge . . . -93 Inflammable Materials. 46,47 Inspection . . . , -19 Insurance — Company's plate fixed . 96 Lightning and fire compared 38, 39,87 Need of . . . -75, 87 Insulators . . . 16, 71 Inverness Post Office — Struck by lightning . . .58 Iowa (U.S.A.)— Cattle damaged by lightning at 49 Iron — Cable . . . . 40, 41 weight . . . .106 52> 54 • 54 56 56 page I RON — continued. Cast plates cracked by lightning 94 Conductor . 17, 27, 45, 46, 51, 54 Cost of, rods . . -59 Earth connection of rods . . 31 Frame buildings Galvanised bands wire Rods Use of, wire Wire, barbed . utility of . Work, ornamental (See Conductor.) Italy — Practice in . . . 27,48 27, 51,46 29,48 II, 12 9, 10 39, 40 • 17 58 Job— Thunderbolts of . . 100, loi Joints — Bonded . . . . 29, 79 Box . . 24, 25, 30, 42, 44 Boxes connecting . . 24, 25 Casting to cable . . 28 Conductor i8 Construction at. . . 18, 25 Earth connection . . 32, 33 Electrical. . . 18,24,26,33 Lead ferrule . . . 28, 46 JMechanical . . . 24 Number of . . . .19 Position of . . . -34 Protection of factory chimneys. 30 Rain-water pipes . 44 JONESCO, Mr. D.— On trees and lightning . . 89 Jupiter's Sacred Fire . . 100 Kasner, Mr. — On increase of danger from lightning in Saxony . . 88 Kea Church, Truro — Struck by lightning . . .60 Kelvin, Lord — On dark lightning . . 99 On protection of explosives and magazines . . . . 47 Kentucky Negro — Superstition as to tree struck by lightning . . . .103 114 INDEX. PAGE Langdon, Mr. W.— On course of lightning . 86, 93 Lead-encased Joint Connec- tion FOR Pipes . . .26 Le WES- Cottages struck by lightning . 77 Lighthouse— Struck by lightning . . -63 Lightning— " A " flash described . 5, 6, 8, 74, 82 Absolute security from danger of, not possible . . 14, 53 Alcohol ignited by . . .104 Altar in church struck by . . 103 Ancient theory of . . .11 Area of protection from . -13 (See Protection). Auracaria, striking . . .95 " B » flash . 5, 6, 8, 9, 65, 66, 67, 93 Balloon struck by . . . 95 Halls, incident of . . 97, 98 Barge struck by . .103 Beehive in tree revealed by . 96 Bell ringing and . . .96 Bicycle struck by . . .96 Cast-iron plates cracked by . 94 Cattle injured by . . -49 Characteriitics of . . .5 Circular action of . . .103 Clear sky . . . . loi Cone theory and . 13,14 Copper, eff'ect of, on . . 11, 12 tea-kettle struck by . 105 Course of, flash . 12, 36, 37, 53, 55, 60, 61, 67, 79 Crosses, supposed protection from . . . . 96 Cruet fused by . . . 93, 93 Damage by, extent and in- crease . . 55, 88 Damage to buildings by, 190 I- 1904 .... ■ 3 Damage to protected building s 60 . 60 ■ 99 UlI]JIUH-LLCLl ,, Dark Destructive aspects of ID, 12 Direct . 86 Disruptive violence of . 10 Distributive nature of 53 Distant effect of • 93 Divided, flash . 78,79 page Lightning — continued. Effects of, examples . 60 88 in Louiury town . 88 Electric railway struck by. 92 Erratic course of 86 ,87 Explosive nature of . 95 ,98 Freaks of . 94 Fulgurites . 11,91 .92 Fusion caused by 91 Globular .... 97 ,98 Gun-cotton 7, 103 Hay, effect on . 94 Hot spring struck by 99> 100 Imitation of . . . iOO Induced current 86 Inductive condenser dis- charge 93 Intensity of 102 Invoking . 99 Iron, effect of, on II 12 Iron-framed building 83 Jupiter's sacred fire . 100 Kalten, flash . . . 10 Lateral discharge 6,53 n Liner struck by. 103 Measurement of lOI, 102 Naphtha ignited by . 103 Ohmic resistance 12 Oscillatory character of . 6 I' Railway carriage struck b> 93 Rain, effect on. 65, 66 81 Resistance to . 12 51 Rifle struck by . 103 Rod man 48 Roman superstitions as to 100 Sacredness of 100 Saluting the 99 Secondary effects of 13 Side flash ... 7 2,93, 103 Sky-scrapers and 49 , 50 Spectrum photographed . 99 Steel chimney struck by 95 Sugar boiler explosion caused by 95 Sundry notes on 95 Table lamp struck b)- 93 Trees, effect on 90, 103 Upward effect of 93, 104 Wallpaper damaged by 48 INDEX. 115 PAGE LiGKTmNG—conimuecl. Water effect on 93 Waterworks struck by 94 Ziindenden flash 10 Lightning Rod Conference, 1881— Earth connection 32 Observers enrolled by 2, 3 Reports to . . . 3 .3 Lightning Rod Conference, 1887— On protected cone . 13 On protection of trees 88 Rules for erection of lightni ng conductors 16 Lightning Research Com- mittee's Report— Collieries .... 20 Conductors 16 , 17 Cost of protection 38 Curvatures 18 Earth connection 19 Explosives 47 Factory chimneys 17 Fixing .... 16 Insulators .... 16 Inspection 19 Instructions to observers . 36,37 Joints .... 18 ■ 3° Masses of metal 18 Materials for rod 17 Organised 2 Ornamental ironwork 17 Painting .... 18 Protection 18 ,29 Report by . . 5 6, 7,8 Rods (failure of) 86 Steel-framed buildings 39 Strokes, various classes . 86 Suggestion and rules (1905) 15 20 Tubular earth . 31 Upper terminals • 16 Liner — . Struck by Kghtning . 103 Lodge, Sir Oliver— Area of protection . 13 Cause of damage to Hotel de ViUe .... 56 Cage protection . . 9 12 55 Cost of protection . . 38 PAGE Lodge, Sir Oliver — continued Demonstrations by . . . 5, 6 Down conductors . . -23 Effects of lightning . . 10 Introduction . . iii, iv, v, vi Iron conductors . . 7, 27 Lightning taking earth through water 95 Testing earth connection . . 36 Maclean, Captain— On action of lightning on trees 90 Magazine for Explosive.s — Protection of . . . .47 Magnetic Cloud — Effect on ship . . . .97 Maine, William — Lightning rod . . . .104 Mansard Roof— Connection and protection of . 48 Maxwell, Mr. Hugh— On lightning and trees . 89 Measuring Lightning Flash ioi Melsen System— Described . . 56, 57 Metals in and on Struc- tures — Connection of 26, 27, 45, 66, 67, 79 Protection of internal masses of 31,81 Use of, as conductors . 18, 54 Michigan (U.S.A.)— Damage reported from . 88 Milan — Globular lightning at . .98 Mills— Struck by lightning . . 68 Moisture — Necessity in earth connection 33, 36, 48, 50 (See Earth Connection.) Mountainous Districts — Effect of lightning in . .11 Municipal— By-laws as to protection of structures . . . .52 Naphtha — Ignited by lightning . . 103 Naples — Protection of hospital at . . 59 I 116 INDEX. PAGE "Nature" quoted . . .95 Nelson Monument, Edin- burgh— Struck by lightning . . 98 Nobel's Explosive Co.'s — Factory at Ardeen struck by lightning . . .85, 86 NORTHCOTE, Mr. C. S.— On globular lightning . . 98 Oak and Beech Trees— Susceptibility of, to lightning 89, 90 Painting — Iron or copper rods . . .18 Palmerston House School, Ross- Struck by lightning . . .80 Paris — Globular lightning at . .98 (See France.) Petroleum Spring— Fired by lightning . . .103 Plans — Marking conductors on . -54 Pliny— On electrical displays . . 96 Pockels, Herr — Measurement of lightning current 102 Post Office— Action of, with regard to light- ning 3 Struck by .... 68 Preece, Sir William— Electrical currents and atmo- spheric resistance . . . 102 Prendiz— Lightning conductor erected at 2 Proctor, Mr. H. B. . 100 Protection— Absolute or partial . . 7, 50, 53 Area of . . i3> H, 55, 58,72 Barbed iron wire . . 11,12 British Association discusses 102, 103 Cage . 7, 9, 21, 27, 34, 46, 47, 53, 5^ Copper wire . . • 11, 21 Cost of . 38,47,50,51,53,54, 56, 59, 71 Horizontal conductors . 15,22 Protection — continued. Iron barbed wire Measure of Methods of Steel-framed buildings PAGE 10, II 7, 50 21-37 • 39 Railway— Carriage struck . . 93 Electric „ . .92 Station „ . • • -11 Rain— Effect of lightning mitigated by 65, 66,81 Rain-water and other Pipes and Gutters — Bonded joint for . . .29 Connection and use of as con- ductors . 41, 42, 43, 44, 46, 48, 50, 51, 53, 56, 57, 69, 70, 73, 11 79, 81, 82, 83, 84, 93 Earth connections . . 31, 33 Ramsgate — House destroyed by lightning at 76 Reimarus — On lightning and lightning con- ductors 91 Rifles— Struck by lightning . . . 103 Rochdale — Strickland's Brewery at, struck by lightning . RocKLiFFE Church, Carlisle- 63 Struck by lightning . Rods, Lightning — Angles of . Chimney . Curves in . Disuse of . Efficacy of Elevation . 21, 22, 25, Fixing Franklin . . • -■, Intercepting, efficacy of Maine Material for Number of Oxidisation of . Solid. 73,74 . 16 17,22 12, 18 • 49 51,55,66 27, 42, 57 . 16 51, 55. 56 • 51 . 104 17,29 • 15 • 17 . i6 INDEX. 117 PAGE Rods, Xjiqwy'^v^o.— continued. Terminal 54 Unit 38 Vertical . . . 15, 17, 32 (See also Conductor, Copper, Iron). Romans— Atmospheric electricity known to ... I, 100 Superstition regarding light- ning .... 100, lOI Use of burial of lightning- struck persons . . .101 Roofs — Barbed connection for iron cable on, with down con- ductors . . . .28 Horizontal conductors on . 84 Mansard 48 Metals, connection of . 15 Thatched . . . -54 (See Cage Conductor). Royal Horticultural Society's Buildings — Specification for, and pro- tection of, at Westminster 40, 41 Royal Institute of British Architects . . .12 Royal Meteorological Society — Lightning Rod Conference . 2 Russia — Attitude of peasantry in, towards lightning . . . -99 St. Andrew's Church, Mark's Tey— Effect of lightning on . -65 St. Botolph's Church, Cam- bridge — Effect of lightning on . -73 St. Dunstan's Church, May- field— Effect of lightning on . . 85 St. Elmo's Fire— Superstition as to . . .97 St. 'Michael's Church, High- gate— Effect of lightning on . .68 St. Pancras Church — Effect of lightning on . . 66 St. Paul's Church, Bedford— Bulged rain-water pipe . . 69 Effect of lightning on . 69, 70 page St. Paul's Cathedral— Aigrettes used at . . . Conductors and earth connec- tions Tubular earths at . . 32 St. Peter's, Rome— Method of protection at . St. Stephen's Church, Car- noustie — Effect of lightning on Saluting the Lightning Saussure's — Alpine travels . Saxony — Practice in . . . Shire Oak Brewery, Walsall — Struck by lightning . Siemens, Dr. Werner von- Electrical effect of storms Sleeve— Connecting points of air termi- nals Southborough Vicarage — Struck by lightning . South Shields— Greenhouse struck by lightning at 34 34 34 58 99 91 61 97 75 Specifications — Church protection Conditions of tender Copper and iron cable Detached residence . Farm buildings Modified cage protection . Royal Horticultural buildings ■ 79 • 43 • 43 . 40 45,46 . 46 . 40 Society 40, 41 Spratt's — Lightning conductor . 72, 73 Springbourne Wesleyan Chapel — Struck by lightning . . 81 Stark, Leopold— On cage conductors . . -55 Steel-framed Buildings — Freedom of, from damage by lightning . . . .39 Stoerhead Lighthouse — Struck by lightning . . .62 118 INDEX. PAGE Storms— Definition . . .5 Electrical effects of . . 97 Velocity of . . 104, 105 Stoves — In buildings, protection of 7, 45 Straps — Connecting . . . 31,45 Stuttgart Town Hall . .51 Sugar Boiler — Exploded by lightning . -95 Surveyors' Institute — And lightning ... 2 Sutton — Effect of lightning on dwelling- houses at ■ .81 Tannery, Hylton Road, Worcester— Struck by lightning . 81 Technical Terms . 106 Telegraph Poles 86 Telegraph Wires 54 Distant storm and . 93 Protective . 68 Utihty of . n Terminals— Air terminals . 71 Connection of 58 59 Protection of . 53 56 Rods of . 52 (See also Aigrettes and Air Terminals). Testing— Admiralty suggestions for. 36 Cage formation . 34 Clamps for 44 Conductor. 34 Earth connection 34 36 Electrical . 20 Frequency of . 36, 5 I, 52 68 Thunder Flower . 103 Tillet. 91 ToRR Head Coastguard Station— Effect of lightning on 85 Trees— Beehive in tree . 96 page Trees —continued. Cedar 95 Circular action of lightning on . 103 Conductivity of . . 93) 89 Effect of lightning on 10, 11, 79, 80, 88, 91 Oak . . -93) 103 Poplar . . . . 89, 93 Side iiash from . . -93 Use of tree struck by lightning 103 Tripe, Dr. On globular lightning . . 98 Typhon— Thunderbolt of . .100 Tubular Earth — Connection . 19, 42, 44 Described . 31, 32 Expense of • • 33 Method of . 32 Resistance . 31 Testing . . . • 34, 35 (See also Earth Connection). Upward Effect of Light- ning 93, 104 Vanes — Protection of 31, 37, 43, 61, 65, 75= 76 Van Gulik, Dr. — Report (1905) by . . 14 Varnish Tank — Exploded by lightning 95 Ventilating Pipes . . 45 (See Rain-water pipes.) Virgil . . i, 100 Vatican Buildings— Method of protection . . 59 Victoria and Albert Museum — Struck by lightning . . .72 Wallpaper of Cott.utf. — Damage by lightning . 85 Waterworks — Effect of lightning on . . 94 Weights of Copper and Iron Conductors . . .106 INDEX. 119 PAGE PAGE West, R. A.— Wire Fences— Explosive action of lightning . 95 Westminster Abbey— Aigrettes on roof of . . .22 Danger of . . 49 Withering — On fulgurites . . . -91 Weybridge, Queen's Road Congregational Church— Struck by lightning . 72, 73 York — Dwelling-house struck by light- ning at . ... 83 99, Woodland Road, W. HANCOCK, '''1=Sl PATENT IRON ROPE CONDUCTORS =— CANNOT RUST. —^ THE UNIVERSITY, BIRMINGHAM. I have seen the lead-covered iron cable made and patented by Mr, Hancock^ of Bristol^ and am very favourably impressed with it. It will be an excellent material for lightning conductors, for which iron is known to be the best substance, except for the corrosion difficulty. Mr. Hancock's in- vention gets over that difficulty, and it is probable that there must be many uses for such protected iron rope. (Sir) OLIVER LODGE. Another scientific report says :— "Exceptionally well adapted lor lightning conductors," The " BUILDER." October 31st, 1908:— " This ingenious method of protection deserves full consideration by Archi- tects and others." " A meritorious invention." WORK EXECUTED FOR— His Majesty's Office of Works, The Imperial Tobacco Company, J. S. Fry & Sons, Bristol University, H. 0. Wilis, Esq., Many Churches & Public Buildings. Testimonials on application. Please send for Pamphlet, Post Free . ABVERTISEMENTS. JiBm. The SIMPLEX STEEL CONDUIT SYSTEM for Electric Wire Protection. fltoands : FOUR GOLD MEDALS For Excellence and General Utility ELECTRICAL SAFEGUARD. ^