I was recently in Cincinnati for the purpose y, of getting a pair of my rotary engines manu- g factured for my own use, it Mitchelsville, to ? be applied to a merchant flouring mill, and o' also one for a gentleman of Grason County, Q Texas, for a saw-mill. But failing to make any satisfactory arrangements to get them ;, made, I procured reciprocating engines for 2 the purposes specified. Embarking in the = flouring mill business ([ think permanently) I shall probably abandon all further attempts to introduce my plan of rotary engine. Could they be properly made, and the facilities for their manufacture be of the best order,, and well systematized, their cost would be less 1 than that ot other engines of equal power, and for many purposes I would strongly recom mend them. The want of capital, to thus es tablish their manufacture, is an effeetual bar rier to my further progress in the business. Being well satisfied that my rotary is the world's last hope, and that any material de viation from my plan, as at present m atured will prove abortive, I feel a strong sympathy for those, not in possession of my experience, who are attempting to invent and mature a rotary steam engine. They will have much to learn, and their knowledge will cost them too dear. An attempt to excel, materially, the reciprocating engine, in point of economy, by substituting a rotary, is chimerical. I claim for my engine cheapness, compactness, and uniformity of action, and economy in the use of steam, equal to the reciprocating engine. Its objectionable features, in its present state of maturity, are not of any prominent charac ter ; the most obvious of which is its liabili ty to derangement by expansion and contrac tion of metal, and the yielding or displace ment of adjusting screws employed in main taining the steam wheels in their proper po sition. To a person experienced in running one, these difficulties are of small moment. J. A. STEWART. Mitchellsville, Tenn., March 9, 1853.