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Remarks on some prevailing Misconceptions concerning the 

 Actions of Machines. By Edward Sang, Esq. Commu- 

 nicated by the Society of Arts for Scotland. * 



In the last paper which I presented to the Society of Arts, 

 I endeavoured to correct the common notion, that the per- 

 formance of a model is representative of that of a machine. 

 In this paper I proceed to expose the fallacy of some prevail- 

 ing notions concerning the actions of machines in general. 



The fancy that machines are capable of generating power, 

 though fostered by a very absurd proclamation from our go- 

 vernment, is now almost entirely abandoned ; and, except from 

 two or three individuals ignorant of the history and of the princi- 

 ples of mechanics, we hear of no attempts at obtaining the 

 reward offered for the perpetual motion. But another fancy, 

 differing less from this than it at first appears to do, is very 

 generally entertained. We are perpetually told of the loss 

 of force whicli arises from the obliquity of the actions of ma- 

 chines, and are called upon to examine cumbrous and ex- 

 pensive contrivances for rendering these actions direct, and 

 for regaining, or even more than regaining, the force that 

 has been wasted. If any arrangement of machinery were ca- 

 pable of destroying force, putting friction out of view, the 

 inverse action of the same machinery would be capable of ge- 

 nerating it. 



The truth is, that every machine, however ill contrived, 

 and however ill constructed, delivers over the whole, and ex- 

 actly the whole, amount of force which put it in motion. Part 

 of that force is expended in overcoming the friction of the rub- 

 bing surfaces, and in encountering the resistance of the air, 

 while the rest goes to produce the particular effect which the 

 contriver of the instrument may have had in view. 



The geometric contrivance of machines, the arrangement 

 of the parts so as to produce particular motions, has unlimited 

 scope. But in a mechanical point of view, the inventor can, 

 profitably, direct his attention only to two objects — economy 

 in the material, and labour necessary to the first construction 

 of the instrument, and the diminution, as far as is practicable, 



* Read before the Society of Arts for Scotland 9th January 1833. 



