VOh. XLII.] PHILOSOPHICAL TRANSACTIONS. 663 



spur comes out, and separates itself from the lever, as appears by fig. 4. It 

 was necessary to make this spur moveable, and give it the figure of a square 

 rule, in order to bring it quite close to the end of the lever, or set it back, as 

 it may be necessary. For this reason the upper part of this spur ab, slides 

 along in a mortise, or groove, of the length of one foot, contrived under the 

 lever, beginning from its extremity b, to which answers the shoulder b, of 

 the spur. 



The rest of the tenant, or its principal parte, is fitted to enter into the mortise d, 

 which is the uppermost part of the foot, fig. 2, 3. They are both pierced with a 

 row of holes, through one of which must be run an iron pin, to unite them, and to 

 form the point of rest, or the hinge of the lever. Towards the other extremity a 

 of the lever, there is a piece of iron c, fig. 8, pi. l6, made arch-wise, under which 

 passes the elastic tailDf,of the rod, fastened to the sliding-pieccFG, and into which 

 catch teeth, made on the said tail, as in fig. 3, pi. 15, or fig. 6 and Q, pi. l6. This 

 iron arch ought to be very solid, because it keeps down the arm, and supports all 

 the effort of the lever. He gives to the sliding-piece fg, which is fitted to the 

 lever, the name of the bracer ; it is a groove made of one piece of wood, repre- 

 sented in its situation in fig. Q, pi. l6. This piece is hollow in the upper surface, 

 as above said, to place the luxated arm into ; this cavity is quilted, and has 3 

 girths, H, of strong leather, with buckles, to tie the arm fast and conveniently. 

 It has on its inferior surface a groove with a dove-tail, kk, to lay hold of the 

 rod of the lever, and to slide in it without being separated from it, unless it be 

 in sliding beyond the extremity b, of the lever, where it pulls out like a drawer, 

 which is easily done, if the bracer has nothing to stop it on the lever. The 

 extremity of the bracer, which answers to the thick end of the lever, is rounded, " 

 in order to enter jointly with it under the arm-pit ; the other gives hold to the 

 piece of iron de, called above by the name of the elastic tail of the bracer. This 

 latter consists of 4 parts : the fork f, which attaches itself to the inferior lateral 

 surfaces of the bracer; the spring f, which is the piece that follows next, the 

 longest and slenderest of all ; the teeth e, and the handle d. 



The use of the new Ambe. — ^The patient, being undressed down to the waist, 

 is placed in the arm-chair, as in fig. 6, pi. 1 6. Next, the lever, furnished with 

 its bracer, is raised and kept in a horizontal position, taking great care, as 

 Hippocrates recommends, to push this bracer as far as may be under the arm- 

 pit to the end of the bone of the arm, and even beyond, if possible, so that the 

 humerus, supported by the bracer in all its length, may be secure against all 

 the power of this machine, and that its violence may only act on those muscles 

 which keep this bone out of its place. Besides the quilting, which the bracer 

 is lined with, a small cushion is put on its extremity, in order to lodge stilt 



