5Q THREE MECHANICAL STR.UCTU RliS. 



tongue, it now remains to mention the advantage to be de- 

 rived from them in a profeffional view ; and, although this is 

 Uot dire6lly in the line of the purfuits of this learned Society^ 

 . yet, fo ftrongly is it conneded with humanity, that it cannot ba 

 laid to be foreign to them, or undeferving their attention. 

 Great benefit of The information derived from thefe cafes, enables us to 

 this knowledge attempt with fafety, the removal of any part of the tongue 

 cancer? ° which may have taken on a difpofition to become cancerous. 



As this difeale in the tongue always begins in a very fmall 

 portion of that organ^ it is, in the eafly ftage, more within 

 the reach of removal than when in any other part of the 

 body ; and, as the glands of the tongue are independent of 

 each other, the cancerous difpofition by which one of them is 

 attacked, does not fo readily communicate itfelf to the others ; 

 and ^he part may be removed, with a greater degree of fe- 

 curity againft a future recurrence of the difeafe, than in 

 other cafes where this malady attacks a portion of a large 

 gland, the whole of which may be under the influence of 

 the poifon, long before there is any appearance of its being 

 difeafed. 



IX. 



Properties of 

 the wheel and 

 axie. 



A compound 

 barrel or roller, 

 by which the *^f 

 purchafe may be /^V 

 greatly aug- 

 mented. 



Account of Three Mechanical Stru6iures not commonli/^otked or 

 hurxihy in which the EffeSi isproduced by the Difference between 

 the ASiionsof Two fimple hijlruments of the fame Defcription; 

 namely, 1. a compound Barrel and Winch ; 2, a compound 

 Screw, and'3. a compound Pump. W. N. 



In the fimple mechanical engine, called the wheel andaxfe^ 

 or barrel and winch, the advantage of the power over th-e 

 weight is known to be as the radius of the wheel or winch is to 

 that of the axle or barrel. If it were, therefore, propofed to 

 increafe that advantage, the handle mufl: either be made longer 

 or the barrel more flender; neither of which can practically 

 be done beyond certain limits in the ufual form; becaufe the 

 handle might be too long for management, or the barrel too" 

 flight to fupport its burthen. The celebrated George Eckhardt 

 is, I believe, the inventor of the conftrudron, Plate III. 

 2. in which the part A of the barrel is larger than the 



part 



