During the trial, the engine pumped 28,360,162 gallons of water, at the rate of 9,105,604 gallons in 24 hours, against a mean total head - including suction, but without allowance for friction or resistance in suction-pipe and pump of 174.99 feet; and, the weight of the gallon being taken at 8.3345 pounds, the duty in footpounds, for each 100 pounds of coal, was 113,271,000.

Computed on the coal used in running, exclusive of kindling and banking fires, the duty per 100 pounds of coal was 138,035,000 foot-pounds.

The report for the year 1883 is as follows:

Ratio of ashes and clinkers to the total fuel, per cent

Total number of revolutions.

Mean head of water, feet.

Number of cubic feet of water delivered into reservoir, per

revolution..

Mean weight of 1 cubic foot, pounds.

8,518,131 × 177.45 × 23.38 × 62.331 × 100

Duty, =

2,077,139

15.5

8,518,131

177.45

23.38

62.331

106,048,000

If the proportion of ashes and clinkers had been no more during the year than during the trial of a week, the duty would have been greater in the proportion of 0.909 to 0.845, and would have exceeded 114,000,000.

STEAM-ENGINES OF MEDIUM SIZE AND MODERATELY HIGH SPEED.

We come now to the consideration of a group of engines, for the most part manufactured in advance of orders, and bought for various purposes, according to the judgment of the purchaser, with or without. expert advice.

Among the manufacturers of steam-engines thus loosely grouped together, it is eminently proper to name Mr. George H. Corliss first ; for although others, not a few, now rival him in certain special qualities, some do this by avowed appropriation of his inventions, no longer protected by patents; while all, no less in the United States than elsewhere throughout the world, are indebted to principles of

which he was among the first to discover the transcendent importance, and to mechanical combinations, or their equivalents, which he was the first to invent.

It must be unnecessary to attempt, in this place, any description of the characteristic features of the Corliss engine. Il a fait le tour du monde. His releasing valve-gear has been criticised by Professor Releaux and by others, as mechanically imperfect; but these criticisms seem not to be well-founded.

No one, it is presumed, objects to intermittent motion in the escapement of a watch, or in the lock of a gun, nor yet in the tripping mechanism of a pile-driver. The advantages of this motion in closing a steam-valve at cut-off are so weighty, and the inconveniences of it, if indeed real, are so slight, that it may well be considered practically perfect up to 70 or 80 revolutions per minute. For speeds much above these, it seems to be ill-adapted.

The wrist-plate, giving a rapid motion to the valves in opening and in closing, and a period of comparative rest at the extremities of its throw, attains, by means mechanically unobjectionable, all that has been sought in vain from impracticable cams.

The valve itself, a cylindrical slide, has established its durability and its tightness by the experience of a generation of men.

Mr. Corliss, as the head and front of the Corliss Steam-engine Company, stands toward the public in a twofold relation: first, as an engineer, prepared to design and construct steam-engines for special service; and, second, as a manufacturer of steam-engines for sale, to be used for various purposes, without special adaptation to any. In the first relation, he nicely adapts all the parts of his mechanism to the attainment of the end in view; and such engines as we have considered are examples of the result.

In the latter relation, the result will depend on the judgment and skill of the purchaser when he is his own engineer, and on the skill of his engineer when he employs one. Engines too large or too small for their load, supplied with water-clogged steam from illarranged or inadequate boilers, or run at unsuitable speeds, or with leaky pistons and mal-adjusted valves, will give no satisfactory results, although manufactured by Mr. Corliss.

These remarks are general, and are applicable to all competent steam-engine manufacturers, with a degree of force proportioned to the real excellence of their respective engines under most favorable conditions.

A Corliss engine at the Lancaster Mills, Clinton, Worcester County, Mass., was tested in February, 1884, under the direct super

vision of Mr. George W. Weeks, agent of the mills, a member of the American Society of Mechanical Engineers, well known to the writer, who vouches for his candor and intelligence.

This is what is usually called a "double engine," that is, a pair of engines, right and left hand, with a fly-wheel and shaft in common, and cranks set at right angles. The dimensions are: diameter of cylinders, 26 inches; length of stroke, 5 feet; fly-wheel, 39 feet in diameter, 6 feet belt-face; air-pump, 34 inches in diameter, 12 inches stroke.

The cylinders are not steam-jacketed. Steam is supplied by five return-tubular, externally fired horizontal boilers, 60 inches in diameter outside of the smaller courses, with 76 flues, 3.25 inches outside diameter, and 19 feet 8 inches long; set with overhanging smokebox, the front flue-sheets being about in the plane of the arch-fronts.

Heating-surface

1345 × 5 = 6725 square feet 28.5 × 5 = 142.5 square feet

Fire-grate area

Ratio of heating-surface to fire-grate area

Vacuum, in pounds per square inch below atmosphere.

Steam-pressure in boiler, in pounds per square inch above atmosphere,

Mean speed of engine in revolutions per minute

Mean piston-speed, feet per minute. . .

Clearance, in terms of volume swept through by the piston

47 to 1

87.

13.02

52.71

527.1

.0239

The test was continued four days, and sets of diagrams were taken six times each day, three times in the forenoon and three in the afternoon. The first set was taken soon after starting the engine, at 6.50 to 6.58 A.M.

The second set was taken between 8.06 and 9.34 A.M.; the third, between 9.48 and 11.12; the fourth, between 2.02 and 3.06 P.M.; the fifth, between 2.48 and 3.44; and the sixth, between 4.03 and 4.48. The least power observed was 641.90 horse-power, the greatest 703.35, a range of only about 9 per cent. The means for the respective days were : —

There were burned under the boilers from 6 o'clock of the evening preceding the first day of the test, to 6 o'clock P.M. of the last day, when the test ended, 57,000 pounds of coal, which yielded 4,600

pounds of dry ashes and refuse, leaving 52,400 pounds of combustible.

Ratio of ash to coal, 8.07 per cent. The hours run were 11 hours each day, 44 in all.

Coal per hour, pounds

Coal per hour, and per indicated horse-power, pounds

Combustible per hour, pounds

Combustible per hour, and per indicated horse-power, pounds

1,295.45

1.93

1,190.91

1.77

A test of the evaporative efficiency of the boilers and coal, not simultaneous with the engine-test, but some time before, gave an actual evaporation of 10.58 pounds of water per pound of coal burned; or, corrected, by estimate, for water blown off during the day, and water pumped in at night, 10.07 pounds.

Computed from the indicator-cards, the quantity of water "visible ' as steam was equal to 8.67 pounds for each pound of coal burned during the test, which would indicate the presence of 13.9 per cent of the feed-water in the liquid form in the cylinder.

The number of diagrams taken may be thought too few to give assurance of the true mean of the power during the 44-hours' run; but if the smallest mean be taken, that for the third day (663.51 indicated horse-power), the coal consumption per hour and per indicated horse-power becomes 1.95 pounds, against 1.89 pounds if the largest mean-power, that for the first day (684.13 indicated horsepower), be taken.

Again, if we take the smallest power observed during the four days, at 4.03 to 4.05 P.M. of the second day, 641.90 indicated horsepower, and compare the result with that obtained by using the largest observed power, at 9.31 to 9.34 A.M. of the first day, 703.35, we have respectively 2.02 and 1.84 pounds per indicated horse-power and per hour, each differing from the mean, 1.93, only 4.5 per cent.

Upon the basis of 10 pounds of water evaporated under actual conditions, for each pound of coal burned, we have 19.3 pounds of feed-water per indicated horse-power and per hour; and by the indicator cards, 16.73 pounds; so that, of the feed-water supplied to the boilers, 86.7 per cent was accounted for by the indicators, and 13.3 per cent was present as liquid water. (Published in "Cotton, Wool, and Iron," Boston, Mass., Feb. 9–16, 1884.)

During the year ending April 26, 1884, the coal burned in the furnaces of these boilers, supplying steam for all purposes, including 3,070 hours actual running-time of this engine, at 670 indicated horsepower, as computed from numerous indicator diagrams, amounted to

1,967 tons, equal to 4,406,080 pounds, which gives 2.14 pounds of coal consumed in the mill, for all purposes, for each indicated horsepower exerted one hour.

It may be thought that too much space has been given to this test; but it is so good an example of valuable work within the reach of nearly all users of steam-engines, that it has been thought well to bring it to notice in this manner.

The Putnam Machine Company, Fitchburg, Mass., were among the earlier manufacturers of an excellent class of automatic cut-off, horizontal engines, of medium speed and moderate power.

Being well described in Tolhausen's Uhland, it will be unnecessary to describe them here. By the use of double-seated poppetvalves and an ingenious combination of cams and levers, the cut-off is controlled by the governor; and an excellent distribution of steam is effected, with satisfactory uniformity of speed.

The writer has occasionally tested an engine of this construction, 12-inch cylinder, 30-inch stroke, during a period of 17 years, and always found it tight, and in perfect order, almost without repairs. This valve-gear is not well adapted to speeds higher than 90 or 100 revolutions per minute.

Charles H. Brown & Co., also of Fitchburg, by means of gridiron slide valves, actuated by cams and levers, and detaching mechanism controlled by the governor, obtain very prompt and full admission, almost instantaneous cut-off, and free release, and produce indicator diagrams almost ideally perfect.

In point of mechanical execution and finish, the Brown engines are singularly beautiful, and in all the higher qualities of design and proportion they are excellent. This engine, also, is described in Tolhausen's Uhland.

The Fitchburg Steam-engine Company, also of Fitchburg, Mass., a newer enterprise, is now making an automatic cut-off engine of much higher order than the small vertical engines described in Tolhausen's Uhland.

They make a peculiar form of centrifugal governor placed on the crank-shaft; a kind of governor which has gained great favor within the last ten years, and assumed a multitude of forms. We shall again have occasion to speak of this governor.

In the form under notice, which is excellent, the eccentric is guided in its transverse motion across the shaft, by means of a sort