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REMARKS.

A. Some crushing took place before shearing.
B. Slight crushing took place before shearing.

C. In the second test one of the wedges slipped and did not bear on the whole length of the key.

E. Inasmuch as these keys were only deep, they tipped slightly in the key way.

H. In the first test there was a defect in the keyway of the pulley.

DISCUSSION.

Prof. Jas. E. Denton.-I want to ask the author of the paper how far he was certain that the unplaned samples which were found stronger than the planed samples varied in size, principally, in fixed cross section.

Prof. Lanza.*-Replying to Prof. Denton's question, I will say that the unplaned specimens were cast in very carefully made rectangular moulds, and their variation of section was certainly very small.

Although the areas are doubtless not exact to the ten thousandth of an inch, it was thought best to give the decimals just as they were obtained by the students, by multiplying the two dimensions together.

*Author's closure under the Rules.

CCCXIX.

THE COST OF POWER IN NON-CONDENSING STEAM

ENGINES.

BY CHARLES E. EMERY, NEW YORK.

(Member of the Society.)

In the years 1864 to 1868 the writer, then an Assistant Engineer in the U. S. Navy, was engaged in experimental duty at the Novelty Iron Works, N. Y., under the general direction of Chief Engineer B. F. Isherwood, then Chief of Bureau of Steam Engineering, U. S. N., and Horatio Allen, President of the Novelty Iron Works, N. Y., Commissioners under authority of the United States to make a series of experiments to assist in determining the limitations of the economical expansion of steam under practical conditions, and other collateral questions relating to the general subject. The results were never published under Government authority, but a general table was handed by Mr. Isherwood to Mr. R. H. Buel, who introduced it into the articles on "Steam Engineering," prepared by him for Appleton's Cyclopædia of Mechanics and the American edition of Vol. II. of Weisbach's Mechanics. The information is, however, in such shape as to be of little service without discussion and analysis by some one acquainted with the objects to be accomplished and the details of the work. The experiments were applicable only to steam engines of the forms then in most general use, and therefore did not include investigations with compound and triple compound engines at the very high pressures since found practicable. The writer having been connected with the work almost from its inception, felt that there were a number of questions which could be settled by further experiments, and perhaps become the basis of commercial value, and a little time before the Government experiments were abruptly brought to a close by a change of administration, he arranged with the Novelty Iron Works for the construction of a small experimental engine designed primarily to determine the quantity of steam which could be secured by lining a steam cylinder with a non-conducting material. The

pressures of 25, 40, 60, 80 and 100 pounds, and show that cost of a horse power in pounds of water per hour decre rapidly from full stroke or 1 at the right to a minimum at a Į of cut-off, which is shorter as the pressure is increased, that after passing such minimum the cost rises rapidly as cut-off is still further increased.

Curve H of the series designated No. 2 represents the c lated quantity of water required per indicated horse power hour in a non-condensing engine using 80 pounds steam pres at different points of cut-off. The calculations take into cons ation the weight of steam required to fill the cylinder to the f of cut-off and also that required to supply the heat transm into work, but make no allowance for cylinder condensation losses by clearance or for deficiency in work due to insuffi area of passages, or to a back pressure in excess of the at pheric pressure.

Curve G is a similar curve based on the additional condition the clearances and ports equal 1-20th of the piston developm

Curve D is the same as D in series No. 1, and its pos above the curves G and H shows the relative extent of the l at different points of cut-off due to cylinder condensation other causes not included in the calculated results for a engine of about 5 horse power.

The curve F was originally interpolated in the position sl from such information as was available at the time to show probable cost of, using steam at 80 pounds pressure in an er developing about 100 horse power. Later experiments show for conditions stated the curve should more nearly approach curve G.

These curves well illustrate methods commonly adopted to termine the influence on the general results of varying conditi The law affecting each condition can only be ascertained s factorily by making a series of experiments varying that condi and keeping all others constant. For instance, in this partic case the weight of steam required in the small engine at var degrees of expansion was obtained by varying the cut-off keeping the steam pressure and revolutions constant, the la requiring a variable resistance which was obtained with a l fan-blower. The outlet was closed, as the resistance was to decreased so that less air was displaced, or just the cont movement to that which would have been required had the ble

pressures of 25, 40, 60, 80 and 100 pounds, and show that cost of a horse power in pounds of water per hour decrea rapidly from full stroke or 1 at the right to a minimum at a po of cut-off, which is shorter as the pressure is increased, that after passing such minimum the cost rises rapidly as cut-off is still further increased.

Curve II of the series designated No. 2 represents the cal lated quantity of water required per indicated horse power hour in a non-condensing engine using 80 pounds steam press at different points of cut-off. The calculations take into consi ation the weight of steam required to fill the cylinder to the p of cut-off and also that required to supply the heat transmu into work, but make no allowance for cylinder condensation, losses by clearance or for deficiency in work due to insuffic area of passages, or to a back pressure in excess of the atm pheric pressure.

Curve G is a similar curve based on the additional condition 1 the clearances and ports equal 1-20th of the piston developme

Curve D is the same as D in series No. 1, and its posi above the curves G and H shows the relative extent of the lo at different points of cut-off due to cylinder condensation other causes not included in the calculated results for a s engine of about 5 horse power.

The curve F was originally interpolated in the position sh from such information as was available at the time to show probable cost of. using steam at 80 pounds pressure in an en developing about 100 horse power. Later experiments show for conditions stated the curve should more nearly approach curve G.

These curves well illustrate methods commonly adopted to termine the influence on the general results of varying conditi The law affecting each condition can only be ascertained s factorily by making a series of experiments varying that condi and keeping all others constant. For instance, in this partic case the weight of steam required in the small engine at var degrees of expansion was obtained by varying the cut-off keeping the steam pressure and revolutions constant, the la requiring a variable resistance which was obtained with a b fan-blower. The outlet was closed, as the resistance was to decreased so that less air was displaced, or just the cont movement to that which would have been required had the bl

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