Report on the Progress and State of Applied Mechanics. 229 



working that inventors have sought to increase the efficiency of the 

 steam ; and amongst the earUest of those who were successful in doing 

 so, may he mentioned Hornblower, Woolf, and other makers of Cornish 

 engines; but your reporters must observe, that if they were to name 

 all those engineers who have given pi-oofs of skill and ingenuity in the 

 manufactui-e of steam engines, the list would be as bulky as the whole 

 of this report. 



87 (a). The most promising method of increasing the eflB.ciency of 

 the steam beyond that which has hitherto been attained is that called 

 SUPEE-HEATiNG ; that is, raising the temperature of the steam beyond 

 the boUing point corresponding to its pressure, and thus enabling it to 

 exert a given force through a greater space than an equal weight of 

 saturated steam would do. 



87 (b). To give an idea of the present condition of the steam engine, 

 it may be stated, that in the most economical class, single-acting pump- 

 ing engines, the duty of one pound of coal is not uncommonly 1,000,000 

 foot-pounds, and has sometimes been raised as high as 1,200,000 ; that 

 in locomotive engines, ordinary land engines, and ordinary marine 

 engines, that duty varies from 200,000 to 500,000 ; that in the most 

 economical class of double-acting land engines, the duty is about 700,000, 

 and that the same result has been attained in marine engines by recent 

 improvements ; and that one of your reporters was lately present at an 

 experiment on a marine engine, in which a duty of 1,945,000 was 

 realized. 



88. The EFFICIENCY OF THE MECHANISM depends on accurate work- 

 manship and proportions, in the same manner with that of machines in 

 general. 



89. A STEAM TURBINE or momentum-wheel, invented by Mr. Gorman 

 of this city, was for some time used at the City Saw Mills. It is much 

 to be desired that some precise experiments should be made on the 

 efficiency of this kind of engine. 



90. Electromagnetic Engines depend, as to their efficiency, upon 

 the law of the transformation of energy in another shape. They can 

 be made to have a considerably greater efficiency than heat-engines ; but 

 they are less economical, owing to the much greater cost of the mate- 

 rials consumed by them. 



91. In the Trains of Mechanism by which power and motion are 

 transmitted from prime movers to the points where the useful work is 

 performed, one of the most important objects to be attained is the 

 diminution of the lost work to the least possible amount, through the 

 reduction of friction and the avoidance of shocks ; and that is accom- 

 plished by accurate workmanship, by adjustment of the strength of 



