100 
ORIGINAL COMMUNICATIONS. 
{a.ai) Boards 12 by 18 inches, with battens on the ends. 
(b.b.) Straps passing under the lower board to make the 
pressure by being rolled around the spindle c. These straps 
are of very strong woollen webbing, such as the saddlers use 
in the construction of reins, &c. 
(c) Spindle of iron, with a ratchet wheel in the centre, hav- 
ing holes in which to place the end of the handle d, in order 
to turn it around. The spindle is protected by strips of wood, 
and partly let into the upper board. An improvement on this 
plan is represented at e. The spindle is made of hard, tough 
wood, with a brass tube, bearing the ratchet wheel, driven on 
the middle, through which the holes for turning it are made. 
The straps instead of rolling up in four places, are rolled up 
in two, one at each end; the ends of the straps being merely 
tacked on to the wood of the spindle. In this form the straps 
may be two or three inches wide. In the iron spindle the 
ends of the straps are wedged into holes cut on each side of 
the collar, represented as at c. The ends of the spindle are let 
into the batten on the upper board, and are kept from flying 
out of place, when pressure is exerted, by small moveable 
plates of iron, (as at f,) which turn on a screw at one end and 
fit under the head of another screw at the other end. 
