This section is from the book "Cassell's Cyclopaedia Of Mechanics", by Paul N. Hasluck. Also available from Amazon: Cassell's Cyclopaedia Of Mechanics.
In making an American breast collar for a horse, assuming that the trace buckles are l 1/2. in. wide, the body of the collar cut straight should be 2 1/4 in. wide and 3ft. long, the lay 11 in. wide to fit the buckles, with the ends turned in for chapes so that the front of the buckles will be level with the end of the body. Put a lining in the chapes and two good loops, or one long loop, behind the buckle; the lay can then be cut of a wavy pattern from loop to loop in the centre, or it can be left straight. Then make four bearers the same as for breeching, but with four breeching dees instead of two dees and two rings; |-in. buckles will do for them; put one on each side between the buckle and loop, and the two others 4 1/2 in. from them towards the centre of the collar, and stitch the lay, loops, and bearers down. Now cut two or three thicknesses of thick fawn serging or a piece of thick felt and cover it with thin patent cowhide or basil, and see that it is the same size as the body both in length and width, joining the cover in the centre underneath and turning it in at the ends, then stitch to the body all along both sides; or stitch in with the lay and do away with this second stitching.
Now cut the shoulder strap to hold it up 2ft. 10in. long and slit it 1 ft. at each end; finish up and punch the slits, and put two rings or large dees on each side of the centre close by the end of the slits for the reins to run through for driving purposes-. If for cart work, it must be made stronger all through and coarser. The sizes given are for gig purposes; for a pony, the measures must be altered in proportion. If necessary, a small dee can be placed in the centre of the collar for putting a martingale billet in, the other end going to the bellyband between the horse's legs.
 
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