Proceedings of the P olytechxic Associatiox. 831 



that eno;ines, which in the opinion of the educated engineer, possess 

 many of the elements considered necessary for economical workings, 

 do not have those elegant, moving details, which fix the attention of 

 the amateur, and delight the eye of the skillful mechanic. Business 

 men seek only to sell, and therefore push into chief importance such 

 points as the purchaser can see and understand. 



Statements are made also regarding actual performance, but they 

 cannot be considered impartial, because the trials up.on which they are 

 founded are made by interested parties, with no competition present. 

 A¥e have therefore to conclude that the purchaser of a steam engine 

 has to base his selection almost exclusively upon the excellence of 

 simple, mechanical details ; and having done this, if the engine works 

 well, and especially if it does better than the old neglected one, with 

 its worn out boilers, he is entirely self-satisfied, and ready to sign a 

 recommendation to the public of the engine which he has selected, 

 thereby benefiting the manufacturer, and flattering his own vanity. 

 But little true progress can be made in this way, as each manufacturer 

 and purchaser knows little more than the result of his own experi- 

 ence. 



To bring the steam engine to a high standard of efficiency, accu. 

 rate, comparative trials should be publicly made of every different 

 system of construction. This would be most satisfactory, if it could 

 be done in the same place, doing the same work, under the same cir- 

 cumstances. This would require the erection of costly experimental 

 fixtures, which could be done by private enterprise for expected gains, 

 or by the combination of several wealthy manufactm'ers, or, better, 

 still, by some scientific organization. The majority of cases must, 

 however, be reached by trying the steam machinery in the actual 

 performance of the duty for which it has been purchased. We desire, 

 then, in our present inquiry, to ascertain methods and means to test 

 the power and economy of the steam engine in a strictly scientific 

 manner, which shall be above criticism, and also under the practical 

 circumstances of every day use. 



We propose first to mention some of the terms in general use on 

 the subject, then to discuss the ways and means employed to measure 

 the power and its cost, and afterward to select proper units of com- 

 parison and point out the manner of their practical application. 



A steam engine is simply a heat engine. The heat evolved by the 

 combustion of fuel is imparted in the boiler to water, separating and 

 agitating its molecules, and thus forming steam. The steam exerts 



