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was done in about half an hour. As tliis afcertains 
a given ftrength of brine on taking out the cord; 
it may be fuppofed that every fibre of the cord is 
equally impregnated with fait. The cord being 
dried, it will be proper to flretch it ; which may be 
done fo as to prevent it from untwifhng, by tying 
three or four yards to two nails, againif a wall, in 
an horizontal pofition, and hanging a weight of a 
pound or two to the middle, fo as to make it form 
an obtufe angle. This done for a week or more 
in a room, will lay the fibres of the cord clofe 
together, and prevent its ftretching fo fad after being 
applied to the intfrument, as it otherwife would be 
apt to do. 
I have mentioned the fizes and principal dimen- 
fions that I have ufed ; as the indruments may as 
well be fimilarly condrudfed as otherways; but I 
do not apprehend it to be very material to agree in 
any_ thing but the drength of the brine on taking 
the cord out of it. If the cord is adapted to the 
indrument fome days before its fird adjudment, I 
apprehend it will be the more fettled. 
Adjujiment of the Hygrometer. 
The box cover being taken off, to prevent its be- 
ing fpoiled by fire, and chufing a day naturally dry, , 
fet the indrument nearly upright, about a yard from 
a moderate fire ; fo that the cord may become dry, 
and the indrument warm, but not fo near as would 
fpoil the fined linen by too much heat, and yet 
fully evaporate the moidurej there let the indru- 
ment day, till the index is got as low as it will go, 
now 
