. Bulletin. Science. Supply cy/inc/e 32 - foot c/f'amefe patjdte wheel. Figure 5.—Conjectural reconstruction of arrangement of driving gear in the Ericsson. Reporters at tlie trial run rode on the pistons. A remark of Thomas Ewbank, sometime Patent Commissioner, became more and more per- tinent as the acrimonious debate over the success or failure of the caloric engine continued. "Why theorize, argue and quarrel for months about the weightof a piece of metal," said Mr. Ewbank, "when the scales are at your elbows?" '* A Prony friction brake dynamometer, although difficu
. Bulletin. Science. Supply cy/inc/e 32 - foot c/f'amefe patjdte wheel. Figure 5.—Conjectural reconstruction of arrangement of driving gear in the Ericsson. Reporters at tlie trial run rode on the pistons. A remark of Thomas Ewbank, sometime Patent Commissioner, became more and more per- tinent as the acrimonious debate over the success or failure of the caloric engine continued. "Why theorize, argue and quarrel for months about the weightof a piece of metal," said Mr. Ewbank, "when the scales are at your elbows?" '* A Prony friction brake dynamometer, although difficult to apply to the ship's engine, could have been used on the so- called 60-horsepower test engine that Captain Erics- son built before proceeding with the Ericsson's engine. '= The scales are no longer at our elbows, and I have found no complete nor entirely consistent set of data; but I have made a calculation based upon data that were published at the time,'^ making such assumptions as now appear reasonable and in every case weighting my assumptions in favor of the engine. The result, at nine revolutions per minute of the paddleshaft, is ^^ Journal of the Franklin Institute, 1854, vol. 38, p. 33. 55 A Prony brake, used to test a rotary steam engine, is described and illustrated in Appletons' Mechanics'" Magazine and Engineers' Journal, 1852, vol. 2, pp. 26, 91. Such a brake was shown at the Mechanics' Fair in Boston and was reported in North American Review, January 1840, vol. 50, p. 227. 36 The most complete listing is in Appletons' Mechanics' Maga- zine and Engineers' Journal, 1853, vol. 3, pp. 39-40. about 250 horsepower. My calculation is shown on pages 59 and 60. A comparison, of sorts, can be made with the reason- ably corroborated performance figures for marine steam engines. The resistance of the Ericsson, in the speed range considered, probably varied more nearly as the cube of the velocity, as Prof. William Norton of Yale University asstimed in his calculati
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