VOL. IX.] PHILOSOPHICAL TRANSACTIONS. J 37 



tan all sorts of leather as well at least as bark alone. This material being gotten 

 in its proper season, it must be very well dried in the sun, and more so than 

 bark ; then housed dry, and kept dry for use ; and when it is to be used, the 

 greater wood may be shaved small, or cleft fit for the engine described below ; 

 and the smaller to be bruised and cut small by the same engine : which done, 

 it must again be dried very well on a kiln, and then ground, as tanners usually 

 do their bark. Such wood as is to be used presently after getting it, will re- 

 quire the more drying on the kiln; otherwise it will blacken and spoil all the 

 leather. Where oak is scarce, thorns may indifferently well supply its place. 

 Birch prepared and used instead of oak, is very fit for soal-leather. As these 

 ingredients will tan better than bark alone, and that with far less charge; so 

 may this invention save the felling of timber when the sap is up ; which causes 

 the outside of the trees to rot and grow worm-eaten ; whereas, if the trees had 

 been felled in winter, when the sap was down, they would have been almost all 

 heart, as they call it, and not so subject to worms. Besides, this invention 

 will greatly improve the value of underwoods. 



The Description of the Engine ahove-mentioned, for Beating and Cutting the 



Materials of Tanning. 



This machine is represented in pi. 6, fig. 4, 5, 6. It consists of a long square 

 wooden block, and of some pieces of iron, to be fastened on it and used about 

 it, viz. an anvil, a hammer, an iron holding the wood to be bruised and cut, 

 and a knife to cut the same. Oak or elm is accounted best for the said block, 

 the dimensions whereof are these: AB, in fig. 4, the length of the block, about 

 4 feet. CD, the breadth thereof, 3 5 or l6 inches. EF, the depth, 8 or 10 

 inches. The iron pieces are: GHIK, in fig. 4, a square cavity to receive a 

 plate of iron, serving for an anvil, to beat and bruise the tanning materials on; 

 which is to be about 4 inches deep, 9 inches broad, and 12 inches long. 

 LMNO, in fig. 4, the iron for clasping and holding fast the materials, to be 

 bruised and cut; which must lie across the engine, about the middle of the said 

 piece of timber ; and it may be about 3 inches broad. P, Q are two hooks at 

 one end of it; which are turned upwards, and must be hooked into the loops of 

 the two hinges that are let in and fastened to the side of the engine RS, in such 

 manner, that this clasping piece may have liberty to be a little raised, for putting 

 the tanning materials under it. At the other side T, in fig. 5, is a single hook, 

 likewise turned upward, to hang a weight upon, whilst the stuff is bruising on 

 the anvil, or cutting by the knife. The button, in fig. 4, serves to take up 

 this piece by : aaaa, on the other side of the block, in fig. 5, are the places for 

 the 4 feet to set. this engine upon, which are to be of a convenient height to 



VOL. II, T 



