

Rotatory Steam- Engine. 269 



his engines possess over the common ones, I have only to add, 

 that like many others not professionally occupied with the science 

 of mechanics, I had my doubts as to the superiority of his inven- 

 tion ; and it was not until I had the experience of ocular demon- 

 stration, confirmed by the judgment of people versed in steam- 

 engines, that my prejudices were removed ; but having witnessed 

 the engines he mentions in his letter to you, at work, and hearing 

 the favourable report of all parties, I now confess myself a com- 

 plete convert. The chief objections urged against these engines, 

 is the fear of greater wear than in others. Now this has been 

 quite satisfactorily proved to be even less. The engine at Messrs. 

 Grimshaw's, (a twelve-horse power,) after working all last summer, 

 and driving all the machinery of the printfield, day and night, (for 

 there was no supply of water to drive the wheel,) was taken 

 asunder, and the sliding valves and water cylinder examined, when 

 no apparent wear or tear was visible, although during the entire 

 period it had never been fresh packed. This was the first engine 

 made of the kind, except the model one at the foundry. It was 

 warranted equal in power and durability to an engine of twelve- 

 horse power on the old construction, and die time of payment left 

 to Messrs. Grimshaw's discretion. They are now so well satisfied 

 that they have paid for it, and so they well might, as it does not 

 require more than half the fuel necessary for one of the best engines 

 on the old principle! The sixteen-horse engine to which Mr. 

 Rider alludes, is at Messrs. Bell's Bleach-works, Ballyclare, where 

 it affords the greatest satisfaction. The twenty-horse engine is at 

 Messrs. Alexander's flour-mills. It drives three pair of mill stones 

 with a full feed of grain, and could readily drive a fourth pair, did 

 the connecting machinery answer, with a pressure of from four to 

 six inches on the mercurial gau^e. In fact, the real power of 

 these engines is yet unknown, and the multifarious advantages at- 

 tending them are such as to demand the serious attention of all 

 manufacturers, and others who have machinery to drive. 



I am sure you will feel great pleasure in giving publicity to this 

 invention through your widely circulated Journal, it being one of 

 the greatest importance to the arts and manufactures; and which, 



