[■ 200 ] 
denotes perfcd dry; and the numbers Increafe with 
the degrees of moidure to loo, which denotes per- 
fect wet. 
On comparing them for feme time, when hung 
up near together in a paOage or dair-cafe, where they 
would be very little atfedted by fire, and where they 
would be expofed to as free an air as podible in the 
infide of the houfe, 1 found that they generally were 
within one degree, and very rarely differed tw^o de- 
grees ; but, as thde comparifbns necefiarily took up 
ibme time, and were frequently interrupted by long 
avocations from home, it was fome years before I 
could form a tolerable judgement upon them. One 
thing I loon obferved, not altogether to my liking ; 
which was, that the flaxen cords, which I made ufe 
of, feemed to make lo much refidance to the entry 
of fmall degrees ot moidure (Inch as is commonly 
experienced .within doors in the dtuation above- 
mentioned) that all tlie clianges were comprized 
within the fird 30 degrees of the fcale ; but yet, on 
expofing them to the warm deam of a wadi-houfe, 
the index quickly mounted to 100. I was there- 
fore delirous of impregnating the cords with fome- 
thing of a faline nature, which daould difpofe them 
more forcibly to attract moidure ; in order, that 
the index might, with the ordinary changes of 
moidure in the atmofphere, travel over a greater part 
of the fcale of 100: howto do this in a regular 
and fixed quantity, was the fubjedf of many ex- 
periments, and feveral years interrupted enquiry. At 
lad, I tried the one here- after deferihed, which 
feemed to anfwer my intentions in a great mealure; 
and though, upon the whole, it does not ap- 
pear 
