improved human beings constructed on the crustacean instead of the vertebrate plan would have seemed quite as likely as that any marked alteration in the American locomotive could ever be introduced.

The weak point was the narrow fire-box, and the limited firegrate area, necessitating rapid combustion, no less than 50, 80, 100 pounds, and occasionally 150 to 180 pounds, of coal per hour on every square foot of grate; and to this admitted defect the American bar-truss frame contributed in some small degree.

But the immense advantages of this rigid frame over the flat slab-frame, which must be almost wholly dependent on the boiler for needful stiffness, are so great that it could never have been given up for the sake of less than 10 per cent increase of fire-grate area.

The Wootten locomotive seems to have overcome this difficulty. By raising the fire-grate above the top of the driving-wheels, room is obtained to spread it out to any desirable width; and an area of 68 to 72 square feet, 8 feet wide by 8.5 or 9 feet long, from two to four times as large as could be obtained between the drivers, is provided. The moderate rate of combustion required on this large grate is easily maintained with a gentle blast, and a variable exhaust-nozzle 4 to 5 inches in diameter gives sufficient draught for all occasions.

The result is, that inferior fuel, coal-slack, anthracite or bituminous, or lignite containing 20 per cent of water, can be used successfully, and in the vicinity of coal-mines with great economy; and higher efficiency is obtained from all grades of fuel.

Fired at two doors, and at a convenient elevation above the footboard, the grates are easily kept clean, and the fire is readily kept in a uniform state.

The large fire-box, with 151 square feet of heating-surface and a combustion-chamber, beyond a bridge-wall of fire-brick, with 32 square feet, present, all together, 183 square feet of most efficient surface, largely exposed to direct radiation from the incandescent solid fuel.

comparative

The incidental advantages are equally marked, immunity from cinders, soot, and smoke, and considerably reduced wear of furnace-plates.

But the most remarkable circumstance is, that raising the centre of gravity is said to have noticeably improved the ease of the engine on the rails, and the steadiness and smoothness of running.

The illustration offered, namely, that a stick loaded at one end can be more easily balanced on the finger with the loaded end upper

most, may not present a true analogy, but it is perhaps as nearly so as comparison with the stability of a vessel with centre of gravity high or low.

On the 1st of January, 1884, the Philadelphia and Reading Railroad Company report 171 of these engines, using waste anthracite exclusively for fuel, and that 83 per cent of the main-line coal tonnage of the previous year had been moved by locomotives using such waste fuel, resulting in a saving during the year, in that item alone, of $378,000.

The first one constructed had completed its seventh year of service, and had run 183,904 miles in coal and freight train service; yet no evidence of wear or deterioration of fire-box plates was apparent. The mean annual mileage of this engine is 26,272.

Twenty engines in all, put in service between January, 1877, and March, 1881, had each run more than 120,000 miles, 7 on passengertrains, 2 on freight-trains, and 11 on coal-trains, with a mean annual run of 33,660 miles, without showing any sensible wear of the fire-box plates.

It may be that the experience with these locomotives is yet too slight to warrant safe conclusions as to their permanent qualities; but they appear to constitute one of America's most important contributions toward the improvement and development of the locomotive of the future.

A locomotive built by the Baldwin Locomotive Works of Philadelphia, for the Central Railroad of New Jersey, designed for fast passenger service, will give a fair idea of good American practice. This engine, No. 169, one of four altogether similar, save that two had cylinders 19 by 24 inches, while this and another had cylinders 18 by 24 inches, is fully described and illustrated in "The American Machinist," New York, Jan. 7, 1882.

It has 4 drivers coupled, 68 inches in diameter; rigid wheel base; tread to tread of drivers and of truck-wheels, 7 feet 6 inches; distance from mid-point between drivers to centre of truck, 14 feet 2 inches; truck-wheels 30 inches in diameter; gauge, 4 feet 8.5 inches. A swinging bolster on the truck gives flexibility to the running gear, which carries the weight of the boiler and engines precisely as two independent four-wheeled carriages would carry it.

The fire-box is set on top of the frame, the upper bar of which slopes forward from the top of the jaws of the trailing-wheels directly towards the main driving-axle, and is joined to the after jaw of that axle-box at the middle of its height; and is 3 feet 7.75 inches wide by 10 feet 5 inches long, giving 38 square feet fire-grate area.

The fire-grate is formed of 10 water-tubes 2.25 inches in diameter outside, and 4 solid bars which can be withdrawn for cleaning out clinkers, and has a slope forward of 12 inches, the rear end being a few inches above the bottom of the water-space. The boiler has 200 tubes 2 inches outside diameter, and 11.49 feet long; 145 square feet of heating-surface in fire-box, 1,175 in flues, and 1,320 in all.

The total weight of the locomotive, in working order, is 93,000 pounds, say 41.52 tons; and normal steam pressure is 140 pounds per square inch above the atmosphere, say 10.5 atmospheres absolute. The train usually consists of five cars; namely, one baggagecar, one express-car, one Pullman drawing-room coach, and two ordinary passenger-coaches; and schedule time, 37 minutes, is easily made between Jersey City and Bound Brook, 32 miles, 52.16 miles an hour. This distance has been run in 33 minutes, say at the rate of 58.2 miles an hour.

Three miles upon the route have been run in 2 minutes and 24.5 seconds, and frequently covered in 2.5 minutes; and a single mile has been run in 45 seconds, timed between mile-posts with a stopwatch. These times correspond to speeds, for three miles, of 74.74 miles and 72 miles an hour; and, for a single mile, 80 miles an hour. The same builders made in 1883, for the Cantagallo Railway, Brazil, three locomotives, bearing the numbers 28, 29, and 30, of 431 inches gauge, weighing 40.5 tons in working-order, which draw trains weighing 40 tons up a grade of 8.3 feet in 100 (438.28 feet per mile), with a succession of reverse curves of 131 feet radius, — 43.8 degrees per 100 feet, by ordinary adhesion alone.

These engines have cylinders 18 by 20 inches; 6 driving-wheels, connected, 39 inches in diameter; wheel base, 9 feet 6 inches; boiler 54 inches in diameter, with 190 flues 2 inches outside diameter and 10 feet 9 inches long, and side tanks carried on the locomotivę.

The most notable change that has been made in the American locomotive in the past twenty years has been a gradual increase of weight. On the Pennsylvania Railroad, since 1867, locomotives of the same class have increased in weight from 33 to 35 tons, up to 41 to 45 tons, in working-order. All their engines have air-brakes applied to the driving-wheels, and all their passenger engines are equipped with scoops for picking up water while running.

All their boilers are made of open-hearth steel, fire-boxes included; rivets and stay-bolts of iron. All have water-grates made inch thick.

of tubes 13 inches diameter outside, and

All locomotives have flexible running-gear, by means of the swinging bolster truck. A perfect system of standard dimensions

and interchangeable parts for engines of the same class, greatly reduces the delay and cost of repairs.

Perhaps the most thorough test of locomotive performance in ordinary work, considered merely as a steam-boiler, and a double steam-engine, ever made in the United States, was carried out by Mr. John W. Hill, in July, 1878, on the Cincinnati, Hamilton, and Dayton Railroad, upon a Baldwin engine, No. 36, drawing a train of 35 loaded box freight-cars, and a caboose-car, weighing in the aggregate 649 tons, and with the mean dead load of engine, tender, coal, and water, 50 tons, 699 tons, or 1,565,583 pounds.

A very complete and well-digested account of this test appears in the Journal of the Franklin Institute, Philadelphia, for April and May, 1870; and only a very brief abstract of results can be reproduced here.

At the time of the test, the engine had been out of the builders' shop 22 months, and had run 55,471 miles, and was taken with only ordinary examination and adjustment. The distance from Cincinnati to Dayton, 57.7 miles, was divided into three runs: Cincinnati to Hamilton, 24.7 miles; Hamilton to Twin Creek, 15.9 miles; and Twin Creek to Dayton, 17.1 miles.

The first run was nearly level for about 6 miles, then rose by a nearly uniform grade of 18.2 feet per mile, to a summit 182.14 feet above the starting-point, and then descended 88.15 feet in 8.8 miles to a point 93.99 feet higher than the starting-point, making the mean grade for the 24.7 miles 3.81 feet per mile.

The aggregate curvature on this first run was 315 degrees 32 minutes 15 seconds, a mean of 12 degrees 46 minutes 29 seconds per mile, divided among twelve curves, chiefly of 1 degree, having a mean radius of 5,032 feet.

The second run presented a nearly uniform grade of 6.68 feet per mile, rising 106.26 feet in 15.9 miles, making the total net ascent in 40.6 miles, 200.25 feet. The aggregate curvature on this second run was 105 degrees 15 minutes, a mean of 6 degrees 37 minutes 10 seconds per mile, divided among three curves of 1 degree, and one of 0 degree 50 minutes, having a mean radius of 6,115 feet.

The third run rises with a nearly uniform grade of 3.84 feet per mile, 65.61 feet in the 17.1 miles, gaining an altitude of 265.86 feet above the starting-point in 57.7 miles, a mean (net) of 4.608 feet per mile. The aggregate curvature on this third run is 256 degrees 54 minutes, a mean of 15 degrees 2 minutes 28 seconds per mile, divided among six curves, mostly of 1 degree, having a mean radius of 4,831 feet.

Considered as a whole, the route presented an aggregate curvature of 677 degrees 41 minutes 15 seconds, a mean of 11 degrees 44 minutes 42 seconds, per mile, with a mean radius of 5,124 feet.

The first run was made in 1 hour and 26 minutes, at the rate of 17.23 miles per hour; but the first 15.9 miles occupied about 1 hour and 7 minutes, a speed of about 14.2 miles per hour, and the 8.8 miles down grade was made in about 19 minutes, nearly double, 27.8 miles per hour.

a speed

The second run heavier in grade but easier in curvature-was made in 42 minutes, at the rate of 23.67 miles per hour, an increase of speed of 37.4 per cent, obtained at great cost of fuel.

The third run occupied 50 minutes, at a speed of 20.5 miles per hour. The whole distance, 57.7 miles, was run in two hours and 58 minutes, running-time, at a mean speed of 19.45 miles per hour.

Sets of diagrams were taken from both ends of both cylinders at regular intervals of 2 minutes, 40 sets during the first run, 20 during the second, and 21 during the third run. Twelve selected sets of these diagrams are published, and show excellent valveadjustment.

Every diagram-324 in number was separately computed for power, and expenditure of steam, the power ranging from 725.94 indicated horse-power on up grade at high speed, to 30.64 indicated horse-power on down grade, at low speed; and the results are tabulated separately for each cylinder, and for each run. A condensed summary is subjoined.