The leading dimensions of boiler and engines are given below. Fire-box, 63 inches long, 34.5 inches wide, 60.5 inches high. Barrel, 10 feet 8 inches long, 48 inches in diameter. Flues, 138, 2 inches outside diameter, 11 feet long. Heating-surface, square feet fire-box, 93.85, tubes 794.82, front tube-sheet 10.00, aggregate 898.67.

Fire-grate area, 15.09 square feet; ratio of heating-surface to fire-grate area, 59.65 to 1.

Engines cylinders, 16-inch diameter, 24-inch stroke; pistonrods, right-hand 2.75 inches, left-hand 2.8125 inches diameter; mean net area of pistons, right-hand 198.09 square inches, lefthand 197.91 square inches; clearance in terms of stroke, .076.

Gauge, 4 feet 8.5 inches; diameter of the four driving-wheels coupled, 61 inches; driving-wheel base, 8 feet; whole length of wheel-base, 22 feet; total weight of engine with two gauges of water, 32.24 tons (72,220 pounds). Weight on driving-wheels, 20.02 tons (44,840 pounds).

The consumption of water above given includes all that was blown off at the safety-valve, and used at the whistle and gauge cocks, and in experiments with a calorimeter. Allowing for these losses, Mr. Hill estimates the quantity used by the engine cylinders in producing power, at 30.02, 31.05, and 29.72 pounds per indicated horse-power per hour, respectively, for the three runs.

At all events, the performance of the engines considered by themselves was highly satisfactory. The coal was Pittsburgh No. 2, screened and picked, supposed to be the best available at Cincinnati.

With a pressure at release of 44 to 45 pounds, and a back-pressure on the pistons of 5 to 6 pounds per square inch above the atmosphere, the loss by unconsumed coal blown out at the smoke-stack must have been considerable, and may have been, as Mr. Hill estimates, 20 per cent, or more. But this only sets in a clearer light the inadequacy of the fire-grate area.

With a grate as in the Wootten engine, four and a half times as large, the highest rate of combustion would have fallen, with equal coal-consumption, from 172 to 38.2 per square foot of fire-grate per hour, and might well have been reduced, through increased economy, to 20 pounds.

On a portion of the first run, from observation 12 to observation 31, the engine ran, in 38 minutes, 8.8614 miles up an incline nearly uniform, of 18 67 feet per mile, equal to 1 in 283, gaining an elevation of 165 44 feet, at the rate of 14 miles per hour.

The total weight of the train at this point was a little over 700 tons, say 1,568,000 pounds, and the absolute lift in 38 minutes was, when reduced to dynamic horse-power,

The mean indicated horse-power during this same period of 38 minutes, deduced from 19 sets of diagrams, was 312.37. The difference, 312.37 206.87 = 105.5, which is 33 77 per cent of the gross indicated horse-power, represents all the resistances of train and engine other than the dead lift.

Mr. Hill estimates the internal resistances of the locomotive, from experiments made with it when run without load, åt average speed, —“diagrams taken as fast as possible,” as equal to 33.384 indicated horse-power, which, divided by 312.37, gives 10.66 per cent; and the additional frictions of the engine, due to the load, at 5 per cent of the remainder, and .05 (100 — 10.66) 10.66) 4.46. The sum, 10 66 + 4 46 = 15 12 per cent, represents the engine resistances; and this subtracted from the gross resistances, 33.77 per cent, leaves 18.65 per cent of the mean indicated power for trainresistances proper, other than the dead lift, equal to 28.16 per cent of the power expended in the dead lift itself.

=

This is undoubtedly too little, as it gives only 2.414 pounds resistance per ton, say If we assume that the descending grade

1

927.9

compensates for an equal height of ascending grade, we have 93.99 fect rise in 24.695 miles, and the co-efficient of resistance becomes All the data of the three runs are brought

1

6.62 per ton, say
338.4
together in the following table:-

The total resistance of the locomotive, ascertained by experiment to be equal to 33.38 indicated horse-power, which is 9.9 per cent of the mean total indicated power (337.17 indicated horse-power), is made up of two parts: first, the resistance of the wheels on the rails, 1 which, at its mean value, 6.688 pounds per ton 334.9

amounts to

17.23 indicated horse-power, equal to 5.11 per cent, leaving 16.15 indicated horse-power, equal to 4.79 per cent of the total mean indicated horse-power, as the sum of the internal frictions of the engine when propelling only itself and its tender, 49.174 tons, at mean velocity. The respective speeds were: for part of the first run, No. 13 to No. 31, ascending grade 18.21 feet per mile, 14 miles per hour; for the entire first run, ascending 182.14 feet, then descending 88.15 feet, net rise 93.99 feet, mean grade 3.809 feet per mile, 17.23 miles per hour; second run, ascending grade 6.683 feet per mile, 22.67 miles per hour; third run, ascending grade 3.837 feet per mile, 20.496 miles per hour. The mean speed, mean net rising grade 3.809 feet per mile, was 19.431 miles per hour. These figures indicate that the rolling resistance of this train was less than it is given in D. K. Clark's tables, than which nothing is more likely. But this whole subject has been too little studied, and the writer has devoted to this trial more time than he could have done if it were not almost alone in this field.

Some examples of locomotive performance, which the writer has taken no little pains to verify, will close this portion of our subject.

Locomotive No. 137, Boston and Albany Railroad, built in the repair-shop of the company at Boston, under the charge of Mr. George H. Colby, division master mechanic, was placed in service April 23, 1883, and after running seven days to Worcester, 44 miles and return, making 616 miles, was put, on April 30, into regular express-train service between Boston and Springfield, making the round trip in 6 hours, about 3 hours each way. The distance, commonly called 100 miles, is, by measurement, 98.63 miles, making the round trip 197.26 miles. She continued in this service until July 10, 1884, 14 months and 11 days, say 438 days, with the loss of only 2 days for trivial repairs, — in one case, the tightening of an eccentric, but made some extra runs, so that her mileage was in all 87,190 miles, making her daily mean for the 438 days 197.65 miles, at the rate of 72,192 miles per annum; and for the 436 days of actual service, 198.11 miles. On the 10th July, 1884, she was taken into the shop; and in the four days, July 11, 12, 14, 15, without any work on nights or on Sunday, her tires were turned, her valves faced,

and all parts were put in perfect order, including painting and varnishing all over; and on the 16th she resumed her regular service.

The road is very crooked, and presents curves of 573 feet radius (10° curves); and although the western end of the route is only 60 feet higher than the eastern end, the rise to the summit, 57.25 miles from Boston, is 893 feet, and the descent thence to Springfield, in 41.38 miles, is 833 feet, making the mean rising grade, going west, 15.5 feet per mile, and going east, 20.13 feet; and there are several inclines, 3 to 5 miles in length, of 38 to 60 feet per mile. The train comprised 2 baggage and express cars, 4 sleeping-cars, and 3 to 5 first-class long passenger-cars, usually weighing and often exceeding 300 tons, say 672,000 pounds, locomotive and tender included. From May 1, 1883, to July 1, 1884, a period of 14 months (427) days), this engine has a record of 84,596 miles, 427 round trips, with a total consumption of coal equal to 1,965.625 tons, 4.603 tons per round trip, 52 pounds per mile, 0.1733 pounds per ton per mile, 1,718.6 pounds per hour, and a mean per hour, on each square foot of grate up grade and down grade of 95.48 pounds. The power could not have been less, as a mean, than 340 indicated horse-power, rising at times, probably, to 600; and the mean consumption of coal was about 5 pounds per indicated horse-power and per hour.

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The oil used for lubrication, in the same period, was 1,120.5 gallons, equal to 75.51 miles per gallon; and the cost of oil and waste was $622.55, equal to 0.736 cent per train-mile, and repairs would not bring the aggregate up to 1 cent. Coal was taken at Boston for the round trip. At the exorbitant price of $5 per ton, the cost of fuel per train-mile was about 11.6 cents, and per mileton, 0.039 cent. There are seven engines of this description now in use on this road, and others in construction. The leading dimensions are as follows: Cylinders, 18 inches diameter, 22 inches stroke; 4 driving-wheels connected, 68.75 inches diameter, 100 inches centre to centre; total wheel-base, 22 feet 4 inches. Boiler, wagon-top, barrel 52 inches diameter outside of small courses, inch thick, fluesheets inch, fire-box & inch, all Nashua Company's steel; 221 semisteel tubes, 2 inches outside diameter, 10 feet 10 inches long between tube-sheets, inch apart; fire-grate area, 18 square feet; heating surface, in fire-box 130 square feet, flues inside 1,140 square feet, total 1,270 square feet. Total weight, 87,000 pounds (38.839 tons); weight on drivers, 55,000 pounds (24,554 tons); normal pressure, 160 pounds per square inch above the atmosphere, say 11.88 atmospheres, absolute.

The "Pacific," built by the Lawrence Machine Shop, of which