TS 320 .N55 Copy 1 THE UNIVERSITY OF MISSOURI BULLETIN VOLUME 21 NUMBER 4 ENGINEERING EXPERIMENT STATION SERIES 20 ENERGY NECESSARY TO SHEAR STEEL AT HIGH TEMPERATURES by GUY D. NEWTON Associate Professor of Engineering Drawing and Machine Design ISSUED THREE TIMES MONTHLY; ENTERED AS SECOND-CEASS MAT- TER AT THE POSTOFFICE AT COLUMBIA, MISSOURI— 1,500 FEBRUARY, 1920 •■'■■■.>tgc»^l THE UNIVERSITY OF MISSOURI BULLETIN VOLUME 21 NUMBER 4 ENGINEERING EXPERIMENT STATION SERIES 20 ENERGY NECESSARY TO SHEAR STEEL AT HIGH TEMPERATURES by GUY D. NEWTON Associate Professor of Engineering Drawing and Machine Design ISSUED THREE TIMES MONTHLY; ENTERED AS SECOND-CLASS MAT- TER AT THE POSTOFFICE AT COLLIMBIA, MISSOURI— 1,500 FEBRUARY, 1920 -rSS o «; •f »• JUM 30 1920 7 ^// Q 7/?/ ^ ^ Energy Necessary to Shear Steel at High Temperatures INTRODUCTION Experimental data concerning the resistance of metals at high temperatures are very limited. One reason for this doubtless is that special apparatus must be constructed to make the necessary tests, as ordinary testing machines operate too slowly to be used with ma- terials that must be manipulated at the high temperatures. But prob- ably a more significant reason lies in the fact that the practical use and application of such information is restricted to a special field, since designers usually have to deal with materials at atmospheric temperatures. In designing certain machines, however, such as shears and presses for working hot steel, it is important to know the shearing resistance of the metal dealt with at the working tempera- . tures. It was in the hope of gaining some information on this sub- ject that the tests herein reported were undertaken. The experimental shear was first constructed with rotary blades designed to cut stock ranging up to three inches in diameter. How- ever, after a number of tests were made with this design, the rotary blades were replaced by an attachment which converted the machine into a straight shear. By this means it becomes possible to make a comparison of the power required by the two methods of shearing. While the results are admittedly mcomplete and somewhat erra- tic due to imperfections in the apparatus, it is hoped that they may prove of some interest to designers of this type of machinery and that others may be encouraged to inaugurate further tests in this field. APPARATUS The Rotary Shear. — The shear as shown by Figs. 1 and 2 con- sists of a heavy fly-wheel mounted on a shaft with suitable bearings, and connected by intermediate gears to two parallel shafts which carry the rotary blades. The speed of the fly-wheel, which is twenty times that of the blades, is recorded by means of a Schaeffer and Budenberg stroke counter operated by a lever which engages a pro- truding key on the intermediate shaft. The stroke counter may be seen at the point d. Fig. 1. As the intermediate shaft revolves only one-fifth as fast as the fly-wheel, it is necessary to multiply the 4 Engineering Experiment Station Series 20 counter readings by 5 to get the speed of the fly-wheel. This ar- rangement was found necessary as the stroke counter would not record accurately at the fly-wheel speed. Fig. 1 The piece to he sheared is caught between the blades as shown in Fig. ?>. These blades are so shaped that each makes a spiral- shaped cut from the stock as it is revolved between them. In order that the blades should not burn off they were made rather blunt, and as it is necessary that they should be exactly in line with each other it will he seen that the action is not strictly a shear in the ordinary sense of this term, but that the blades really crush their way thru the metal. It is believed, however, that the energy required in this ac- tion is not widely difl^erent from the energy required for actual shear- ing except as it develops a tensile stress in the specimen. For holding the stock in position between the blades a special steel plate, shown at c, Fig. 1, was provided. This plate has holes at the ends made to fit over the ends of the blade shafts, and a third hole of suitable size at the center thru which the stock is inserted. The shear is driven by means of a belt from a line shaft to a Energy Necessary to Shear Steee -cr 6 Engineering Experiment Station Series 20 clutch pulley on the fly-wheel shaft. The energy for shearing the specimen is supplied by that left in the fly-wheel after the clutch is thrown out. By counting the revolutions of the fly-wheel from the time the clutch is thrown out until it comes to rest, and making due allowance for friction, the energy necessary to shear the specimen is determined. FiG. 3. Rotary Blades. The Straight Shear. — The straight shear attachment, as shown in Fig. 4 is driven by one only of the rotary blade shafts. The at- tachment consists of a stationary blade (A) and a reciprocating blade (B) which is operated by the eccentric (C). Two cast iron guide blocks (D) hold the blades in their proper positions and these guide blocks are bolted througli and held by two steel plates (E) which are threaded over the driving shaft on either side of the eccentric. The outside plate (E) is not shown in the figure. Furnace. — The metal was heated in a gas fired furnace made by the Denver Fire Clay Company. Pyrometer. — The temperatures were taken with a Hoskins Ther- mo-Eiectric Pyrometer, used as shown in Fig. 5 the end of the couple being inserted to the mid-point of the specimen thru a hole just large enough to receive it freely. This arrangement was decided upon after other schemes had been tried and it is believed that it resulted in giving very nearly the true temperatures of the steel. Energy Necessary to Shear Steel . 7 METHOD OF CONDUCTING TEST A piece of steel exactly the same dimen.^ions as the piece to be sheared, with the pyrometer attached as in Fig. 5, is placed in the furnace. When the desired temperature is reached the sample is withdrawn and the temperature read every 10 seconds during the cooling process. By repeating this operation several times it became Fig. 4- Straight Shear Attachment possible to plot a curve of temperatures related to time (Fig. 10) by ineans of which the temperature of the sample at intervals during the time of shearing might be approximately known. After these temperature tests, the sample is again placed in the furnace, together with the duplicate piece to be sheared. While the specimens are being heated, the shear apparatus is started and its 8 . Engineering Experiment Station Series 20 friction deteniiined. This is done by tlirowing off the power after the fly-wheel has attained a known speed, and allowing it to come to rest without interference. The friction of the whole apparatus in foot pounds per revolution is the kinetic energy in the fly-wheel at the initial speed, divided by the number of revolutions it makes after the clutch is thrown out. When the specimens are at the desired temperature, the shear is again started. After the fly-wheel speed has been recorded, the clutch is thrown out and the specimen withdrawn from the furnace Fig. 5 and inserted in the shear. The p'yrometer reading at the time the steel leaves the furnace, the time required to withdraw the specimen and place it in the shear, and the number of revolutions it makes before coming to a stop are recorded. RESULTS The original records and computed results of each series of tests are arranged in Tables I to V. Column 1 gives the test number. Two series of tests were made, the first numbered from 1 to 25 and the second from 1 to 110. In column 3 the speeds of the fly-wheel are given. These are the initial speeds of the wheel at the time the power was thrown off. Energy Necessary to Shear Steel 9 In column 3 are recorded the kinetic energies of the fly-wheel at the initial speeds recorded in column 2. These figures give us there- fore, the energy available for overcoming the friction of the machine and for shearing the specimen. These values were computed as follows: — K. E. = ^ I w2. Where w = the angular velocity of the wheel in radians per second. I ^ its moment of inertia, W/g k- = 217.875 (units, foot and pound). W := the weight of the wheel in pounds. g = the acceleration due to gravity := 32.2 (units, foot and second). This value for 1 was determined by taking the average of sev- eral independent computations. In column 4 are recorded the number of revolutions made by the fly-wheel after the power was thrown ofT. The figures in column 3 give the energy in foot pounds consumed by friction during each revolution of the fly-wheel. The friction of the shear varied considerably, especially during the first series of tests when the machine was new. For this reason friction tests were made frequently, usually before and after each shearing test. It was found that oiling the machine regularly was very effective in keeping the friction within a narrow range of variation. The total friction required to stop, column 6, is the product of the friction per revolution (col. 5), into the number of revolutions recorded in column 4. This gives the energy, in foot pounds, con- sumed by friction while the shear was coming to rest. The shearing energy, column 7 is the difference between the total available energy in the fly-wheel, (col. 3) and the energy consumed by friction (col. 6). This therefore is the total energy expressed in foot pounds required to overcome the resistance of the metal to shear. Column 8 gives the areas in square inches of steel sheared. It will be seen that the smaller specimens were sometimes cut two or more times during the same test. Column 9 gives the shearing energy in foot pounds per square inch. This is equal to the total shearing energy from column 7, divided by the area sheared. Colunm 10 gives the temperature of the specimen at the time of shearing. These figures were found by subtracting the fall in tem- perature during the time the specimen had been out of the furnace, as shown by the temperature curves, from its temperature at the furnace. In cases where two or more cuts were made the average 10 Engineering Experiment Station Series 20 time was used. Temperature curves for several sizes of steel are shown in Fig. 10. Column 11 gives the dimensions of the specimens sheared. In tables I and II the results of tests with the rotary shear are tabulated. Table I gives the results with several sizes of cold rolled steel shafting; Table II, the results with 1J4" chrome vanadium steel. As a comparison of the strengths of these two grades of steel, the shearing energies required from Tables I and II are plotted against temperatures in Fig. 6. ^ wwww. — — — — er curi/e 3ho\/\/s resulis Chrome-l/anadium >3t._ er curi/e shotA^'S results C R Steel Shafting. , cr Upp ^ ^ 5000 Sks c *v///7 d) ^■^-.i Lowi Q. : ^^^'^-'^ ^ i^/iih ^ Aono o ^'^-^^ =» + 1 ^^^ ± a ^ ^^». - ,3. ^5^0 ri O^O, 50Cia, >^ i. ^^>, d) tH"^^ 5 ^"* ■■-■^ y -S— ^^ j£ 2000. () — =^-'^-=;=^|-?— rrr J nKfTT-f-U-J? CT^ c - 1 ooo a c • fOOO i£00. I40O 16 OO. I8O0. Temperature Degrees Fbhr. Fig. 6 Results with the Rotary Shear. 2000. Tables III, IV and V show the results obtained by shearing- various specimens of steel with the straight shear. The curves in Fig. 7 were plotted from data in Tables II and III. As the test specimens in both cases were 1^" chrome vanadium steel,, the curves allow a comparison of the energy required by the two styles of shear to cut the same material. As would be expected from the shape of its blades, the rotary shear required much more energy. The action is in fact more nearly a double shear. Fig. 8 shows the energy required in straight shear to cut Illinois Steel Company's medium grade test specimens. The data are from Table IV. Fig. 9 shows the power required to cut two grades of steel in Energy Necessary to Shear Steei. 11 straight shear. One of these specimens was a rather high carbon steel bar 1" x IJ/^", while the others were very soft steel in bars about Vz X 2" cut flatwise. The data are from Table V. Fig. 10 shows the drop in temperature for various specimens at half-minute time intervals. C 6000. Q) Ol 500Q 4ooa en c o 10 5000. 20O0 r I GOO. _ ^_. T 1 1 1 Upper cur\/e shows results i "+*l 1 ■« "■-f,.,^^^ 1 1 1 1 , u ,^-n i Lower (,uri/^c y^riuwn reomm v^iih fhe Straight Shear. T^ ^ \ "^^^ J ni 1 U Sii °- I - 1 i i '5' w J 1 , 1 1 1 1 M 1 1 1 M 1 1 1 ^ ^v-^ i / ' 1 /i* "ti. i: ^^^ J , t) d ^a^4 ! 1-4-L. *o pi 4^ "^■^ 1 "^>. S^X""""' 1 , -^ ^^^-^ sh-«^® <5 Z^ ^"^^ZS"-*. -^ ^^ j j ^ ^^^^ •s. on ^-t T ^^T" P 1 "*""4«, II 1 . p 1 '*■ ■" '^ ^ Vn 1 . 1 : "T+. p ! 1 i ; : : PT"^^-,, o ^''- J^^ o Ti^ " Tr 1000. 1200 1400. Temperature ISOO 1800. 20O0. Degrees Fahr. Fig 7. A Comparison of I4 Chrome-Vanaoium Steel with F?otaf?y and Straight Shears. ::i5ooo §r 4000 ,-^3000 u. V.- ^2000 .H 1000. to 1 I 1 1 — III! — 1 1 1 1 — [III — 1 1 1 1 — nn — "■«*(- _J = 5K -=5::55=""="===""~"=='=: ::::::::::::i3,:::±: E=-: :¥? = i;;::::-::ii:::i:: : ± itiL "- = - ^ 1000 1200. 1400. 1600 leoo. zooo. Temperature. -Degrees Fahr. Fig 6. Med. Grade Ilu.St Co. Test Specimen. 12 Engineering Experiment Station Series 20 lOOO 1200. I400. IdOO. I800. Tempera\orQ ' Deqrees Fahr. Re. 9. A Comparison of Two Specimens. 2000. 2100 b , ^s - s 2000 ,. "^s s. ^i .5 S '^^ ^^^ s L. V^^ '"s I80C5. \ 2». S^ ^ L ^^ 5s^ ^s. 1 ^ ^N ^ i. 'r \ ^^^^ '"s s: ^ V ^^N. N^ o laoo - -^ s \^< V. 1? ^ ^ ^^^ ?*« -1- ',- \ ^.r ^»,^ ''s^lt - s ^>, X^^ ^< ^i in ^. ^. S S^' ^v ^ ^ s ^N ^^ ><- >- JjTsS^ k (T ^L ^^ ^». 7>sl»jr'' ' T*<,v5Li^ V \ ^''^ rT>L^5'.' 'tn:5V ' ^ 160O, s ^^ ^w J Irr^'^t^Jr^ Q '*'*'~ ^. ^ S ^/o iT"""^- *3l s S " ^V^^a' >>^ ^1.1 s s V,<^ T r--. r*Z L S s-. iS-'^lt -5-. X 5 V iV*'^ D - s^ kit ^W». s 5^ x^ SL 2 I400. __ :s ^ir?i ■^^ s ^-^ X^s ^ " i^'^^ft ^--^ I S. N® cT ^-^ N^ S.Ajy _ 5 Z I^OO ^k, ^s^'^^ I2O0 'i^v5'e >« <^/ ^sC?! a^l^^ iiooL 1 .. . , 1 1 iiiiii.niHii.iiiiiJ o Fie. 10. Tempepature Curved for C.R. Shafting. Energy Necessary to Shear Steel 13 CONCLUDING REMARKS Tlie shearing energies could have been represented fairly well by straight lines within the range of temperatures thru which it had been possible to work. The points indicate, however, that a slight curve as shown is more nearly correct. The curves should probably meet the zero line at the melting temperature, and become more nearly horizontal as atmospheric temperatures are approached. The greatest source of error was doubtless due to difficulties in determining the friction of the machine, as an error of a few pounds in the friction for each revolution would make a considerable dif- ference in the results. This is especially true when the fly-wheel makes a large number of revolutions in coming to rest. By making frequent friction tests an attempt was made to reduce the error from this cause as much as possible. In shearing specimens of small diameter with the rotary shear it was difficult to make some of the specimens revolve while the cutting was in process. This practical trouble caused the rejection of a number of tests, as in these cases the piece was not completely cut off. The exact composition of these specimens was not known. At the time this work was carried on, it was practically impossible to purchase special steel, and these specimens were from ordinary stock. The shearing strength has not been referred to because it is im- possible to formulate an expression for the shearing strength in terms of the energy reciuired that will hold true for all temperatures and all grades of steel. The energy required to shear hot steel is usually assumed to equal the product of the shearing strength in pounds per square inch, times the area in square inches, times the stroke in feet, the result being in foot pounds. The stroke in these experiments is of course equal to the thickness of the metal sheared. But the foregoing ex- pression for the energy is manifestlj' not true, because the resistance which the blade encounters is not constant, but decreases as the stroke proceeds. For very hot metal the resistance at any point in the stroke is approximately equal to the product of the shearing strength multiplied by the area yet to be sheared. It is also true that the working stroke is never equal to the thickness of the metal sheared, except when the steel is very hot, as rupture takes place usually before the stroke is completed. The cooler the metal, the earlier in the stroke will rupture take place. It is probable also that the point of rupture will vary with different grades of steel even at the same temperatures. 14 Engineering Experiment Station Series 20 TABLE I. C. R. Steel Shafting With Rotary Shear. 3. 4. 5. 6. 7. 8. 9. 10. 11. K ^1 I. ^t/i £tH c o ^E ^ cQ 9 10 31 12 13 14 15 16 17 22 23 24 116 119 120 120 115 118 119 119 115 118 116 115 117 112 113 114 114 118 115 118 117 16080 16910 17200 17200 15800 16640 16910 16910 15800 16640 16080 15800 16350 14980 15285 15512 15512 16640 15800 16640 16350 267 38.0 303 '• 197 " 156 " 90 48.0 187 54.1 256 45.5 296 " 273 39.0 264 '■ 325 35.7 305 309 " 223 36.7 354 30.8 297 286 " 395 27.6 225 28.1 240 234 " 10140 11500 7490 5490 4340 10120 11630 13460 10650 10300 11600 10880 11040 8170 10910 9150 8800 10900 6325 6750 6580 5940 3.25 1827 1760 IV.. 5410 " 1665 17(.5 9710 4.87 1990 1540 11260 2370 1455 11460 2350 1545 6520 3.14 2075 1798 2 ] 5280 1682 1800 3450 1098 1945 5150 1640 1695 6340 2010 1625 4480 1427 1885 4920 1565 1885 5310 1690 1905 (>810 2170 1636 4375 1394 1853 6362 2013 1685 6712 2140 1668 5740 1825 1723 9475 4.90 1932 1846 2 ' .'. 9890 2021 17o5 9770 1992 180(. D. TABLE IL Chrome-Vanadium Steel With Rotary Shear. 4 6 10 11 14 15 16 17 18 19 20 21 22 23 15800 15800 15800 15800 16080 li)()40 16350 1(.640 16910 1(.910 l(i350 16350 16640 16350 16910 16910 16910 16640 16910 253 38.3 249 " 205 " 325 35.4 338 36.4 384 " 310 " 270 38.8 309 288 '• 285 365 34.0 361 34.6 350 404 359 353 " 325 353 9680 9540 7860 11505 12303 13977 11284 10746 11989 1 1 1 SO 11060 12410 12500 12110 13980 12430 12214 11245 10760 6120 2.45 2500 16o0 II4 6260 '• 2555 1690 7940 3220 1530 4295 1.227 3500 1710 3777 3080 1450 2663 2170 1820 5066 4125 1430 6164 5025 1200 4921 4010 1230 5730 4670 1220 5290 4315 1215 3940 3210 1570 4140 3375 1520 4240 3450 1625 2930 2390 1735 4480 '■ 3650 1685 4696 3812 1385 5395 4400 1240 6150 " 5010 1080 Energy Necessary to Shear Steel 15 TABLE III. Chrome-\'anai)ium Steel ix Straight Shear. 3. 4. 5. 6. 7. 8. • 9. 10. 11. •- ■^■r.% 24 117 16350 345 40.3 13900 2450 2.454 998 1860 11.4 D. 25 117 16350 270 40.3 10880 5470 3.1.81 1485 1765 29 120 17200 270 34.0 9180 8020 3.081 2175 1575 30 117 16350 443 30.0 13290 3060 1.227 2490 1460 32 118 16(40 458 30.0 13750 2890 2355 1575 34 118 16640 489 29.0 14200 2440 1975 1650 35 119 16910 490 29.0 14220 2c,yo " 2190 1590 36 120 17200 500 29.0 14500 2700 2200 1475 Zl 120 17200 489 29.0 14200 3000 '• 2445 1400 38 120 17200 517 28.0 14500 2700 2200 1370 39 120 17200 517 28.0 14500 2700 '■ 2200 1405 40 119 16900 500 30.7 15350 1560 " 1272 1890 41 120 17200 535 '• 16410 790 '• 644 1815 43 120 1 7200 536 " 16475 725 590 1925 44 120 17200 52i) 16300 900 734 1920 47 120 17200 462 14175 3025 2460 1355 " 48 121 17490 464 14250 2920 2380 1315 49 121 17490 4 84 14850 2290 1865 1350 50 121 17490 480 14740 2410 19o5 1405 52 118 16640 23 S 30.0 7140 9550 3. '.SI 2580 1425 ii 11714 16480 320 9(,00 6880 1870 1555 54 121 17490 408 12250 5240 1425 1735 55 121% 17670 415 12440 5230 1420 1780 56 122 17780 468 14040 3740 1015 1785 57 121 17490 482 14440 3050 827 1815 58 122 17780 476 28.7 13650 4130 1122 1770 •• 59 1211/0 17670 420 12050 5620 1525 1590 60 125 18640 390 11200 7440 2020 1460 '• • 63 1221/. 17880 282 8080 9800 " 2660 1215 64 1241/2 18500 297 8525 9975 2710 1232 '• 65 124 18350 240 6880 11470 3110 1220 >> 66 124 1S350 255 7320 11030 3000 12.30 '• 67 123 ISO 74 187 31.0 5840 12234 3320 1210 •• 68 122 17780 140 32.0 4480 13300 " 3610 1175 16 Engineering Experiment Station Series 20 TABLE IV. III. St. Co.'s Med. Gr.\de Test Spec, in Straight Shear. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. w-= c5 2 f^ I- V ?^ dm c o ■c S ^ Ji li 69 118 16640 501 26.0 13000 3640 4.1 888 1725 '7i,;^-Vi. 70 120 17200 554 14400 2800 3.46 811) 1820 '7i.-^M/2 71 120 17200 516 13400 3800 4.23 877 1745 72 120 17200 510 13250 3950 4,23 935 17(.5 " 7.^ 12111; 17670 586 15220 2450 2.05 1195 1785 "V..-^^V« 74 11 1;, 17050 445 11570 5 4 SO ■ 3.75 1460 1590 1x21/4 76 120 17200 457 11880 5320 3.00 1770 1380 1.x 11/2 77 120 17200 452 11750 5450 3.00 1830 1350 " 78 120 17200 577 " 15000 2200 1.50 1465 1365 " 79 120 17200 586 " 15200 2000 1.50 1332 1270 " 80 120 17200 534 139(10 3300 1.50 2200 1175 " 81 119 16910 325 8450 8460 3.00 2800 1205 " 82 120 17200 300 7800 9400 4.50 2090 1250 1 y^2Vi TABLE V. Miscellaneous Specimens in Straight Shear. S3 118 16640 4'fO 30. 14700 1940 2.9 (.69 1510 14x2.1 84 119 16910 518 29. 15050 IS'.O ■4.0 465 1570 " 85 119 16910 532 15420 1490 5.25 284 1618 " 86 116 16080 491 14200 1880 5.25 358 1625 " 87 118 16640 509 14770 1870 5.25 356 1665 " 88 119.5 17050 509 14770 2280 6.30 362 1660 " 89 119. 16910 400 11600 5310 4.50 1 1 80 1745 1x1.5 90 119 16910 358 103 SO (i530 4.50 1450 1650 92 120 17200 410 11900 5300 0.00 884 1430 i/>x2. 93 120 17200 338 9800 7400 4.50 1645 1545 1x1.5 94 120 17200 320 9280 7920 4.50 1760 1508 " 95 120 17200 388 11250 5950 6.00 993 1405 1/2x2 96 119.5 17050 382 11080 5970 3.00 1987 1390 1x1.5 97 120.5 17380 427 12370 5010 4.00 1255 1295 1/2x2 98 '21. 17490 385 11150 6340 3.00 2150 1280 1x1.5 99 120 17200 328 9500 7700 3.00 2570 1245 " 100 120 17200 322 9350 7850 3.00 2620 1235 " 101 12i\ 17200 394 11425 5775 4.00 1445 1160 1/2x2 102 119.5 17050 391 11340 5910 4.20 1420 1165 1/2x2.1 103 119.5 17050 392 11370 5680 4.20 1355 1160 104 117.5 16480 450 27 . 12140 4340 3.0 1450 1600 1x1.5 105 117. 16350 368 10420 5930 " 1975 1385 " 106 117.5 16480 350 9450 7030 " 2345 1255 " 107 119. 16910 336 9070 7840 " 2610 1155 " 108 118.5 16810 294 7940 8870 " 2950 1070 " 109 119 16910 390 10500 6410 2135 1145 " 110 117.5 16480 375 10100 6380 •' 2130 1225 '• 111 117.5 16480 316 8540 7940 •' 2645 1100 " THE UNIVERSITY OF MISSOURI BULLETIN ENGINEERING EXPERIMENT STATION SERIES EDITED BY E. J. McCAUSTLAND Dean of the Faculty of Engineering, Director of the Engineering Experiment Station Some Experiments in the Storage of Coal, by E. A. Fessenden and J. R. Wharton. (Published in 1908, previous to the establishment of the Experiment Station.) Vol. 1, No. 1. — Acetylene for Lighting Country Homes, by J. D. Bowles, March, 1910. ' Vol. 1. No. 2. — Water Supply for Country Homes, by K. A. McVey, June, 1^10. Vol. 1, No. 3. — Sanitation and Sewage Disposal for Country Homes, by W. C. Davidson, September, 1910. Vol. 2, No. 1. — Heating Value and Proximate Analyses of Missouri Coals, by C. W. Marx and Paul Schweitzer. (Reprint of report published previous to establishment of Experiment Station.) March, 1911. Vol. 2, No. 2. — Friction and Lubrication Testing Apparatus, by Alan E. Flowers, June, 1911. Vol. 2, No. 3. — An Investigation of the Road Making Properties of Mis- souri Stone and Gravel, by W. S. Williams and R. Warren Roberts. Vol. 3, No. 1. — The Use of Metal Conductors to Protect Buildings from Lightning, by E. W. Kellogg. Vol. 3, No. 2.— Firing Tests of Missouri Coal, by H. N. Sharp. Vol. 3, No. 3. — A Report of Steam Boiler Trials under Operating Condi- tions, by A. L. Westcott. Vol. 4, No. 1. — Economics of Rural Distribution of Electric Power, by L. E. Hildebrand. Vol. 4, No. 2.— Comparative Tests of Cylinder Oils, by M. P. Weinbach. Vol. 4, No. 3. — Artesian Waters in Missouri, by A. W. McCoy. Vol. 4, No. 4.— Friction Tests of Lubricating Oils and Greases, by A. L. Westcott. No. 14.— Effects of Heat on Missouri Granites, by W. A. Tarr and L. M. Neuman. No. 15.— A Preliminary Study Relating to the Water Resources of Mis- souri, by T. J. Rodhouse. No. 16. — The Economics of Electric Cooking, by P. W. Gumaer. No. 17.— Earth Roads and the Oihng of Roads, by H. A. LaRue. No. 18.— Heat Transmission Thru Boiler Tubes, by E. A. Fessenden and J. W. Haney. No. 19. — Geology of Missouri, by E. B. Branson. The University of Missouri Bulletin— issued three times monthly; en- tered as second class matter at the postoffice at Columbia, Missouri— 1,500 LIBRftRY OF CONGRESS 003 129 927 5