APPENDICES OF THE SKIN. 89 
none of those inequalities of surface by which hairs are cha- 
racterized. 
If a quantity of wool be spread upon a table, covered 
with a linen cloth, and pressed down, in different directions, 
it is obvious that each hair will begin to move in the direc- 
tion of its root, as if it had been rubbed between the fingers. 
The different hairs, thus moving in every direction, become 
interwoven with each other, and unite into a continuous 
mass. ‘This is the felt with which hats are made. Curled 
hairs entwine themselves with one another more closely 
than those which are straight, though flexible, as they do 
not, like these, recede from the point of pressure in a 
straight line ; and hence hatters employ various methods to 
produce curl in the short fur of rabbits, hares, and moles, 
which they employ. This is accomplished, chiefly, by ap- 
plying the solution of certain metallic salts to the fur, by a 
brush; so that, when the hairs dry, the surface which was 
moistened, contracts more than the other, and produces the 
requisite curve. 
Hair which has been pulled from the skin, is not so fit 
for felting as that which has been cut by the shears. In 
the former case, the bulb, at the base, offers considerable re- 
sistance to the motion of the hair. This is the reason why 
even the short furs are cut off by sharp instruments. 
Although straight hairs do not form so close and conti- 
nuous a felt as curled hairs, from their tendency to procede 
in a straight line, in the direction of the root; yet this pro- 
perty is of great advantage to the hatter. He spreads over 
the surface of his coarser cloth, a quantity of fine straight 
fur; and, by pressure, these fine hairs move inwards in the 
direction of their roots, and thus form a coating; the base 
of the hairs being inserted in the cloth, while the extremt- 
ties are free. 
