TABLE 8. HYPERBOLIC LOGARITHMS. No. Log. No. Log. No. Log. No. Log. No. Log. 9.00 2.1972 9.05 2.2028 9.10 2.2083 9.15 2.2137 9.20 2.2192 9.25 2.2246 9.30 2.2310 9.35 2.2354 9.40 2.2407 9.45 2.2460 9.50 2.2513 9.55 2.2565 9.60 2.2618 9.65 2.2670 9.70 2.2721 9.75 2.2773 9.80 2.2824 9.85 2.2875 9.90 2.2925 9.95 2.2976 1.01 0.0099 3.00 1.0986 5.00 1.6094 7.00 1.9459 1.05 0.0487 3.05 1.1151 5.05 1.6194 7.05 1.9530 1.10 0.0953 3.10 1.1341 | 5.10 1.6292 7.10 1.9600 1.15 0.1397 3.15 1.1474 5.15 1.6390 7.15 1.9671 1.20 0.1823 3.20 1.1631 5.20 1.6486 7.20 1.9740 1.25 0.2231 3.25 1.1786 5.25 1.6582 7.25 1.9810 1.30 0.2623 3.30 1.1939 5.30 1.6677 7.30 1.9879. 1.35 0.3001 3.35 1.2090 5.35 1.6771 7.35 1.9947 1.40 0.3364 3.40 1.2238 5.40 1.6864 7.40 2.0015 1.45 0.3715 3.45 1.2384 5.45 1.6956 7.45 2.0018 1.50 0.4054 3.50 1.2527 5.50 1.7047 7.50 2.0149 1.55 0.4382 3.55 1.2669 5.55 1.7138 7.55 2.0215 1.60 0.4700 3.60 1.2809 5.60 1.7228 7.60 2.0281 1.65 0.5007 3.65 1.2947 5.65 1.7316 7.65 2.0347 1.70 0.5306 3.70 1.3083 5.70 1.7405 7.70 2.0412 1.75 0.5596 3.75 1.3217 5.75 1.7491 7.75 2.0477 1.800.5877 3.80 1.3350 5.80 1.7578 7.80 2.0541 1.85 0.6151 3.85 1.3480 5.85 1.7664 7.852.0605 1.90 0.6418 3.90 1.3610 5.901.7750 7.90 2,0668 1.95 0.6678 3.95 1.3737 5.95 1.7834 7.95 2.0731 2.00 0.69314.00 1.3863 6.00 1.79188.00 2.0794 10.00 2.3026 2.05 0.7178 4.05 1.3987 6.05 1.8000 8.05 2.0857 10.25 2.3273 2.10 0.7419 4.10 1.4010 6.10 1.8083 8.10 2.0918 10.50 2.3514 2.15 0.7654 4.15 1.4231 6.15 1.8164 8.15 2.0988 10.75 2.3749 2.20 0.7885 4.20 1.4351 6.20 1.8245 8.20 2.1041 11.00 2.3979 2.25 0.8110 4.25 1.4469 6.25 1.8326 8.25 2.1102 12.00 2.4849 2.30 0.8329 4.30 1.4586 6.30 1.8405 8.30 2.1162 13.00 2.5626 2.35 0.8544 4.35 1.4701 6.35 1.8484 8.35 2.1222 14.00 2.6390 2.40 0.8755 4.40 1.4816 6.40 1.8563 8.40 2.1282 15.00 2.7103 2.45 0.89614.45 1.49296.45 1.8640 8.45 2.1342 16.00 2.7751 2.50 0.9163 4.50 1.5040 6.50 1.8718 8.50 2.1400 17.00 2.8332 2.55 0.9361 4.55 1.5151 6.55 1.8795 8.55 2.1459 18.00 2.8903 2.60 0.9555 4.60 1.52606.60 1.8870 8.60 2.15 18 19.00 2.9444 2.65 0.9746 4.65 1.5369 6.65 1.8946 8.65 2.1576 20.00 2.9957 2.70 0.9932 4.70 1.5475 6.70 1.9021 8.70 2.1633 21.00 3.0445 2.75 1.0116 4.75 1.5581 6.75 1.9095 8.75 2.1690 22.00 3.0910 2.80 1.0296 4.80 1.5686 6.80 1.9169 8.80 2.1747 23.00 3.0355 2.85 1.0473 4.85 1.5790 6.85 1.9242 8.85 2.1804 24.00 3.1780 2.90 1.0647 4.90 1.5892 6.90 1.9315 8.40 2.1860 25.00 3.2189 2.95 1.0818 4.95 1.5994 6.95 1.9387 8.95 2.1916 30.00 3.3782 by the weight per cubic foot of steam at the pressure as measured will give the weight of steam consumed during one stroke. From this should be deducted the steam saved by compression as shown by the diagram, in order to get a true measure of the economy of the engine. Having thus determined the weight of steam. consumed for one stroke, multiply it by twice the number of strokes per minute and by 60, which will give the total weight consumed per hour. This divided by the horse power will give the rate per horse power per hour. Cylinder condensation and reëvaporation. When the exhaust valve opens to permit the exit of the steam there is a perceptible cooling of the walls of the cylinder, especially in condensing engines when a high vacuum is maintained. This results in more or less condensation of the live steam admitted by the opening of the steam valve; but if the exhaust valve is caused to close at the proper time so as to retain a portion of the steam to be compressed by the piston on the return stroke, a considerable portion of the water caused by condensation will be reëvaporated into steam by the heat and consequent rise in pressure caused by compression. Ordinates. Parallel lines drawn at equal distances apart across the face of the diagram, and,perpendicular to the atmospheric line. They serve as a guide to facilitate the measurement of the average forward pressure throughout the stroke, or the pressure at any point of the stroke if desired. Eccentric. A mechanical device used in place of a crank for converting rotary into reciprocating motion. An eccentric is in fact a form of crank in which the crank pin, corresponding to the eccentric sheave, embraces the shaft, but owing to the great leverage at which the friction between the sheave and the strap acts, compared with its short turning leverage, it can only be used to advantage for the purpose named above. Eccentric throw is the distance from the center of the eccentric to the center of the shaft. This definition also applies to the term "radius of eccentricity." Eccentric position. The location of the highest point of the eccentric relative to the center of the crank pin, measured or expressed in degrees. Angular advance. The distance that the high point of the eccentric is set ahead of a line at right angles with the crank. In other words, the lap angle plus the lead angle. If a valve had neither lap nor lead, the position of the high point of the eccentric would be on a line at right angles with the crank; as for instance, the crank being at o° the eccentric would stand at 90°. Valve travel. The distance covered by the valve in its movement. It equals twice the throw of the eccentric. This refers to engines having a fixed cut off. In the case of an engine with a variable automatic cut off the travel of the cut off valve is regulated by the gov ernor. Lap. The amount that the ends of the valve project over the edges of the 'ports when the valve is at mid travel. Outside or steam lap. The amount that the end of the valve overlaps or projects over the outside edge of the steam port. Inside lap. The lap of the inside or exhaust edge of the valve over the inside edge of the port. Lead. The amount that the port is open when the crank is on the dead center. The object of giving a valve lead is to supply a cushion of live steam which, in conjunction with that already confined in the clearance space by compression, shall serve to bring the moving parts of the engine to rest quietly at the end of the stroke, and also quicken the action of the piston in beginning the return stroke. Compression. Closing of the exhaust passage before the steam is entirely exhausted from the cylinder. A certain quantity of steam is thus compressed into the clearance space. regulate the speed of The governor controls. steam pipe, opening or Throttling governor. Used to engines having a fixed cut off. the position of a valve in the closing it according as the engine needs more or less steam in order to maintain a regular speed. Automatic or variable cut off. In engines of this type the full boiler pressure is constantly in the valve chest and the speed of the engine is regulated by the governor controlling the point of cut off, causing it to take place earlier or later according as the load on the engine is lighter or heavier. Fixed cut off. This term is applied to engines in which the point of cut off remains the same regardless of the load, the speed being regulated by a throttling governor as explained above. Isochronal or shaft governor. This device in which the centrifugal and centripetal forces are utilized, as in the fly ball governor, is generally applied to automatic cut off engines having reciprocating or slide valves. It is attached to the crank shaft and its function is to change the position of the eccentric, which is free to move across the shaft within certain prescribed limits, but is at the same time attached to the TABLE 9. AREAS AND CIRCUMFERENCES OF CIRCLES. Diam. Area. Circum. Diam. Area. Circum. Diam. Area. Circum. 975.90 110.74 8.2957 10.210 9.6211 10.995 12.566 12.566 4.25 14.186 13.351 4.5 15.904 14.137 19.635 15.708 5 5 25 21.647 16.493 5.5 23 758 17.278 6 28.274 6.25 30.679 6.5 33.183 7 38.484 7.25 41.282 7-5 44.178 8 9.5 10.25 82.516 10.5 86.590 57.334 34 18.5 268.803 58. 119 34.25 921.32 107.60 934.82 108.38 989.80 111.52 1017.8 113.09 20 314. 160 62.832 35.5 18.849 19.635 20.420 21.991 22.25 388.822 69.900 38 1134.11 119.38 22.776 22.5 397.608 70.686 38.25 1149.08 120. 16 23.562 23 415.476 72.256 38.5 1164.15 120.95 50.265 25.132 23.25 424-557 73.042 39 1194.59 122.52 8.25 53-456 25.918 23.5433.731 73.827 39.25 1209.95 123.30 8.5 56.745 26.703 24 452.390 75.398 39.5 1225.42 124.09 9 63.617 28.274 24.25 461.864 76.183 40 1256.64 125.66 9.25 67.200 29.059 24.5471.436 76.969 40.25 1272.39 126.44 70 £82 29.845 25 490.875 78.540 40.5 1288.25 127.23 10 78.540 31.416 25.25 500.741 79.325 41 1320.25 128.80 32.201 25.5 510.706 80.110 41.25 1336.40 129.59 32.986 26 530.930 81.681 41.5 1352.65 130.37 95.033 26.25 541.189 82.467 42 1385.44 131.94 11.25 99.402 35.343 26.5 551.547 83.252 42.25 1401.98 132.73 11.5 103.869 36.128 27 572.556 84.823 42.5 1418.62 133.51 12 113.097 37.699 27.25 583.208 85.608 43 1452.20 135.08 12.25 117.859 38.484 27.5 593.958 86.394 43.25 1469.13 135.87 12.5 122.718 39.270 28 615.753 87.964 43.5 1486.17 136.65 13 132.732 40.840 28.25 626.798 88.750 44 1520.53 138.23 13.25 137.886 41.626 28.5 637.941 89.535 44.25 1537.86 139.01 13.5 143.130 42.411 29 660.521 91.106 44.5 1555.28 139.80 14 153.938 43.982 29.25 671.958 91.891 45 1590.43 141.37 14.25 159.485 44.767 29.5 683.494 92.677 45.25 1608.15 142.15 14.5 165.130 45.553 30 706.860 94.248 45.5 1625.97 142.94 15 176.715 47.124 30.25 718.690 95.033 46 1661.90 144.51 15.25 182.654 47.909 30.5 730.618 95.818 46.25 1680.01 145.29 |