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BRAIDING MACHINE.

The invention of this instrument is claimed by Aldereto, a Portuguese physician, but itsform and uses were first described by his pupil Amatus, in the year 1554. Some aresolid, and some hollow; some corrosive, and some mollifying. They generally owe theirelasticity to linseed oil, inspissa'ted by long boiling, and rendered drying by litharge.This viscid matter is spread upon a very fine cord or tubular web of cotton, flax, or silk,which is rolled upon a slab when it becomes nearly solid by drying, and is finally polishedin the same way.

Pickel, a French professor of medicine, published the following recipe for the com-position of bougies. Take 3 parts of boiled linseed oil, one part of amber, and oneof oil of turpentine; melt and mix these ingredients well together, and spread thecompound at three successive intervals upon a silk cord or web. Place the piecesso coated in a stove heated to 150° F.; leave them in it for 12 hours, adding 15or 16 fresh layers in succession, till the instruments have acquired the proper size.Polish them first with pumice-stone, and finally smooth with tripoli and oil. This pro-cess is the one still employed in Paris , with some slight modifications; the chief ofwhich is dissolving in the oil one twentieth of its weight of caoutchouc to render thesubstance more solid. For this purpose the caoutchouc must be cut into slendershreds, and added gradually to the hot oil. The silk tissue must be fine and open, toadmit of the composition entering freely among its filaments. Each successive layerought to be dried first in a stove, and then in the open air, before another is applied.This process takes two months for its completion, in forming the best bougies calledelastic; which ought to bear twisting round the finger without cracking or scaling, andextension without giving way, but retracting when let go. When the bougies are to herhollow, a mandril of iron wire, properly bent with a ring at one end, is introduced intothe axis of the silk tissue. Some bougies are made with a hollow axis of tin foil rolledinto a slender tube. Bougies are also made entirely of caoutchouc, by the interventionof a solution of this substance in sulphuric ether, a menstruum sufficiently cheap inFrance , on account of the low duty upon alcohol. There are medicated bougies, thecomposition of which belongs to surgical pharmacy. The manufacture of these instru-ments of various kinds forms a separate and no inconsiderable branch of industry atParis . MM. Feburger and Lamotte are eminent in this line.

BRACES . (BreMles, Fr.; Hosentrdger, Germ.) Narrow fillets or bands of leatheror textile fabric, which pass over the shoulders, and are attached behind and before tothe waistbands of pantaloons and trousers, in the act of wearing them, for supportingtheir weight, and bracing them up to the body. It is a useful modern invention, super-seding the necessity of girding the belly with a tight girdle, as in former times.

BRAIDING MACHINE. ( Machine a. lacels, Fr.; Bortenwerkcrstuhl, Germ.) Thisbeing employed not only to manufacture stay-laces, braid, and upholsterers’ cord, butto cover the threads of caoutchouc for weaving brace-bands, deserves a description inthis work. Three threads at least are required to make such a knitted lace, but 11,13,or 17, and even 29 threads are often employed, the first three numbers being preferred.They are made by means of a frame of a very ingenious construction, which moves bya continuous rotation. We shall describe a frame with 13 threads, from which thestructure of the others may be readily conceived. The basis of the machine consists oc

four strong wooden uprights, A, figs . 156, 157, 158, occupying the four angles °f arectangle, of which one side is 14 inches long, the other 18 inches, and the height of the #rectangle about 40 inches. Fig . 15b is a section in a horizontal plane, passing throughthe line a b of fig. 1'37, which is a vertical section in a plane passing through the centre of