454 PHILOSOPHICAL TRANSACTIONS. [aNNO 1740. 



The dimensions of the pieces of lead were, the greatest length 23^^ inches, 

 the mean breadth 4-^, and the depth or thickness 4 inches. 



The Description and Draught of a Machine for reducing Fractures of the Thigh. 

 By Mr. Henri/ Ettrich, Surgeon. N° 459, P- 562. 



This machine consists of no more than a wheel and pinion, with their axles; 

 the roch, or snagged wheel, being herein accounted as part of the great wheel, 

 fixed in a light frame of about 2 feet long, (see fig. 1, pi. 10) the whole not 

 exceeding the weight of 1 5 pounds ; and when taken to pieces, by unscrewing 

 the frame-pieces, may be packed up in a common rush-basket, belted to the 

 side, and conveyed to any distance. The room it takes up in working is not a 

 full yard, and it may be set up and fixed for use in a few minutes. In using 

 this machine, the surgeon needs only one assistant ; whereas, in most other 

 methods, their number is most troublesome and ipconvenient : the business of 

 this assistant is only to mind the surgeon's orders, and move the winch accord- 

 ing to his direction. When the extension is sufficient, the engine stays itself, 

 and continues the tension of the limb, by the assistance of this roch, or toothed 

 wheel, whose teeth are cut fine enough to stay the engine at every line of an 

 inch, and which is fixed on the back of the aforesaid great wheel, both to the 

 cross by the help of screws, and on its arbor by having its centre squared out, 

 so as to fix tight on it, and so near the frame as only to allow a bare clearage : 

 its teeth, standing counter to the former, admit the spring or catch, fixed on 

 the inside of the frame, to slip over its vertex, without interruption; but in a 

 reverse rotation, or when the engine is about to come up, it flies into the spaces, 

 and stops it. The upper part projects about an inch from the frame, so that 

 being pressed on by the finger of one hand, the inferior part is elevated above 

 the range of the teeth, to admit the coming up of the engine, which is to be 

 directed by the other hand being applied to the winch in any degree. This 

 engine has its power so commanded, that it may be used without restriction, 

 from the most robust to the most tender frame, as it acts and exerts its power 

 in proportion to the resistance made. This extension is made deliberately, 

 steady, equally, and in one continued line, without the least variation. And, 

 in oblique fractures of the thigh, where the bones are apt to ride, and there- 

 fore require a continued extension in a certain degree, to prevent the limb's 

 shortening after the cure, such a machine must be of excellent service; having 

 the property of increasing or decreasing the extension at pleasure, and to be 

 perfected without the least jar or tremor. 



The necessary appendages are bands, by which the engine extends the limb. 



