94 Transactions of the American Institute. 



This pump is very efficient for drainage and circulating pur- 

 poses, "vvhere large masses of water are to be moved. It is simple 

 in construction, with no parts liable to wear or get out of order; 

 and we recommend it for a first premium. 



The foregoing comprises all of the cases m which a practical 

 trial was made of the articles exhibited. The results show that 

 such a trial should be made of all machinery entered for compe- 

 tition. The mere professional opinion of a judge is not conclu- 

 sive to others, as every man's judgment is necessarily influenced by 

 the comparatively narrow field of his own experience. Nothing 

 can be satisfactory and conclusive but the result of practical experi- 

 ments; these are convincing to all. 



As these trials are the first ever made under the auspices of the 

 American Institute, we desire to call attention to the general plan 

 pursued. 



Every person who buys a steam engine of any kind desires to 

 get his work done for the least possible cost; therefore, with all 

 reliable machinery, the question is to know the cost of useful work 

 in pounds of coal. All experiments which do not ascertain this 

 fact are worthless. Experience has proven that for short experi- 

 ments the best way to ascertain the cost is to measure the quantity 

 of water fed into the boiler in a given time to maintain the water 

 level. This eliminates all errors due to unequal filing, and the 

 number of pounds of coal of average quantity required to evapo- 

 rate the feed-water is easily estimated. 



Next, the useful work must be in some way measured. This is 

 shown in a pump by the quantity of water discharged agiiinst 

 pressure. In an ordinary steam engine it should be measured by 

 a dynamometer upon the shafting, as the net power can only be 

 calculated approximately from indicator diagrams. In the pump 

 trials the indicator was used in connection with the records of water 

 evaporated by boiler and water discharged by the pump. 



The table shows, therefore, the cost of the indicated horse-power 

 and of the useful work; it also indicates the particular fault of 

 each pump. 



For example, the engine with the tightest piston gives the most 

 economical result by the indicator, and the worst result of all in 

 useful work; showing that the power was absorbed in friction and 

 in passing the water back and forth by a leaky pump piston. 

 Another pump fell behind in the water delivered per horse-power, 

 but gained in economy of steam sufficient to overbalance the loss 



