Beport of Suferixtexdent. 73 



and the mean speed during the experinieuts with the two hirge 

 engines was substantially the same. The exact ditterence may lie 

 calculated for the hypercritical as follows: One engine used li)05.5 

 pounds of water per hour and the other 20(*T.T pounds, or six tenths 

 of one per cent, "moi-e than the lirst. ISTow, the speed of the meter 

 was at least required to he doubled or increased one hundred per 

 cent to produce the diiierence in rate of two and a half per cent. So, 

 since one hundred is to .0 as 2.5 is to .015, tJie difference in the rate of 

 the meter duriiKj the tioo OKjltie txperiinents wan Jif teen thomandths 

 of one per cent. 



An alleged misunderstanding in regard to taking into considera- 

 tion the amount of fuel burned makes it necessary to discuss this 

 point fully. 



It was at first intended to measure only the dynamometer power 

 and the water pumped into the boiler, so as to ascertain the amount 

 of steam required to do the useful work. The reasons for this were 

 that the indicated power would include the necessary friction of the 

 engine, which could not bo made available for a useful purpose, and 

 the judges decided that the water could be measured during a short trial 

 much more accurately than the coal. The boiler had forty-tives(|uare 

 feet of grate surface, and the trials could conveniently last but eight 

 hours, so any error of judgment in estimating the quantity of fuel 

 on tlie grate bars or the cleanliness of the fires at the beginning or 

 end of the trial would be a large per centage of the whole (quantity of 

 coal consumed. (See exhibit B.) The iiulicator power would, how- 

 ever, contirm the dynamometer power, and so also the coal burned 

 should be proportioned to the water used, for water always takes up 

 the same quantity of heat when evaporated from the same tempera- 

 ture, and like quantities of coal of the same quality will always fur- 

 nish the same heat, and therefore evaporate the same (juantity of 

 water, which evident fact has been proved l)y the published record of 

 numerous lengthy experiments. 



In the original draft of the regulations of the trial (exhibit C), in 

 order to form a ground for obtaining these confirmatory results if 

 desired, it was stated that the engines might be indicated and the 

 coal might be weighed. I>efore being signed l>y the judges, arrange- 

 ments were made to indicate the engines and the fact was expressly 

 stated in the regulations, while the wording us to tlie coal was not 

 changed. On the contraiy, l»y authni-ity of the judges, the attention 

 of the exhiljitors was called to the instruments used durln;j' the trials 



