3&4

BOOK IX.

piece keeps the ends of the bow distended, and is placed a cubit distant fromthe head of the bellows ; the ends of this piece are mortised into the endsof the bow and are joined and glued to them ; its length without the tenonsis a foot, and its width a palm and two digits. There are, besides, two othervery small pieces glued to the head of the bellows and to the lower board,and fastened to them by wooden pegs covered with glue, and they are threepalms and two digits long, one palm high, and a digit thick, one half beingslightly cut away. These pieces keep the ends of the bow away from thehole in the bellows-head, for if they were not there, the ends, forced inwardby the great and frequent movement, would be broken.

The leather is of ox-hide or horse-hide, but that of the ox is far preferableto that of the horse. Each of these hides, for there are two, is three and ahalf feet wide where they are joined at the back part of the bellows. Along leathern thong is laid along each of the bellows-boards and each of thebows, and fastened by T-shaped iron nails five digits long ; each of thehorns of the nails is two and a half digits long and half a digit wide. Thehide is attached to the bellows-boards by means of these nails, so that a hornof one nail almost touches the horn of the next; but it is different with thebows, for the hide is fastened to the back piece of the bow by only two nails,and to the two long pieces by four nails. In this practical manner they putten nails in one bow and the same number in the other. Sometimes when thesmelter is afraid that the vigorous motion of the bellows may pull or tearthe hide from the bows, he also fastens it with little strips of pine by means ofanother kind of nail, but these strips cannot be fastened to the back pieces ofthe bow, because these are somewhat bent. Some people do not fix thehide to the bellows-boards and bows by iron nails, but by iron screws,screwed at the same time through strips laid over the hide. This methodof fastening the hide is less used than the other, although there is no doubtthat it surpasses it in excellence.

Lastly, the head of the bellows, like the rest of the body, consists of twoboards, and of a nozzle besides. The upper board is one cubit long, one and ahalf palms thick. The lower board is part of the whole of the lower bellows-board ; it is of the same length as the upper piece, but a palm and a digitthick. From these two glued together is made the head, into which, when ithas been perforated, the nozzle is fixed. The back part of the head, whereit is attached to the rest of the bellows-body, is a cubit wide, but three palmsforward it becomes two digits narrower. Afterward it is somewhat cutaway so that the front end may be rounded, until it is two palms and asmany digits in diameter, at which point it is bound with an iron ring threedigits wide.

The nozzle is a pipe made of a thin plate of iron ; the diameter in front isthree digits, while at the back, where it is encased in the head of the bellows,it is a palm high and two palms wide. It thus gradually widens out, especiallyat the back, in order that a copious wind can penetrate into it; the wholenozzle is three feet long.