64 On the Fallacies oftlie Rotatory Steavi- Engine. 



and uniformity to the crank-engine — and there is a radical fault 

 inherent in the very nature of rotatory mechanism, from which 

 it follows that the rotatory engine can never be rendered 

 either an economical or a durable machine. We have further 

 shewn that, even if the rotatory engine could be made econo- 

 mical and durable, its very nature renders it imsuited to the 

 great purposes of steam navigation and inland locomotion, — 

 objects to which it has been considered peculiarly applicable. 

 We deemed it an appropriate and instructive conclusion to our 

 inquiry, to examine into the action of the crank, for the pur- 

 pose of discovering what those remarkable qualities are which 

 have given to the crank of the common steam-engine, its un- 

 rivalled superioi'ity as an element for the production of circular 

 motion, and a degree of perfection unattainable by any other 

 mechanism. We have seen that well-constructed crank steam- 

 engines are daily pei'forming duty, which is within ten per cent, 

 of the theoretical maximum of possible effect — of absolute per- 

 fection — that this practical perfection arises from the simplicity 

 of the crank, from its wonderful adaptation to the nature and 

 laws of matter and of circular motion in connection with recti- 

 lineal motion — from its reduction of errors either in construc- 

 tion, adjustment, or management, so as to work well without 

 the absolute necessity of greater intelligence, expertness, and 

 precision, than belongs to ordinary workmen ; and from the 

 compensating nature of the arrangements of its structure, by 

 which it is accommodated, in a remarkable degree, to the ne- 

 cessary imperfections of all human mechanism. 



It is my earnest desire, that this exposure may have the ef- 

 fect of inducing some of my ingenious countrymen to direct 

 their exertions for the advancement of the arts and industry of 

 Scotland, to other and more promising subjects of invention. 

 A wide field is open to their exertions in the useful applications 

 of the mechanical powers of the common steam-engine to the 

 wants of growing civilization, and to the improvement of the 

 condition of the human race. Let them direct their exertions 

 to these objects, with the same industry and unity of purpose 

 which they have already displayed in the pursuit of the fasci- 

 nating fallacy of a rotatory steam-engine, and they will one day 

 be reckoned in the glorious list of those who have been the be- 

 nefactors of their kind, and the ornaments of Scotland. 



