54 On HYGROMETERS. 
fall out; and to make it keep in, I lengthened it by adding 
to each end.a little coat of fealing-wax. 
I continued in England more than ten years, and during 
all that time after the firft change, I perceived no alteration. 
The magnets had the fame freedom in their box, and the 
little fhutter continued with the added fealing-wax to fit 
its grooves, till fome weeks after my fecond return to A- 
merica. 
As I could not imagine any other caufe for this change 
of dimenfions in the box, when in the different countries, 
I concluded, firft generally that the air of England was 
moifter than that of America. And this I fuppofed an ef- 
fe&t of its being an ifland, where every wind that blew 
muft neceflarily pafs over fome fea before it arrived, and 
of courfe lick up fome vapour. [afterwards indeed doubt- 
ed whether it might be juft only fo far as related to the city 
of London, where I refided; becaufe there are many caufes 
of moifture in the city air, which do not exift to the fame 
degree in the country; fuch as the brewers and dyers 
boiling caldrons, and the great number of pots and teaket- 
tles continually on the fire,. fending fourth abundance of 
vapour; and alfo the number of animals who by their 
breath continually increafe it; to which may be added, 
that even the vaft quantity of fea coals burnt there, do in 
kindling difcharge a great deal of moifture. 
When I was in England, the laft time, you alfo made for 
mea little achromatic pocket telefcope, the body was brafs, 
and it had a round cafe, (I think of thin wood) covered 
with fhagrin. All the while I remained in England, 
though poflibly there might be fome fmall changes in the 
dimenfions of this cafe, I neither perceived nor fufpected 
any. There was always comfortable room for the tele- 
feope to flip in and out. But foon after I arrived in Ame- 
rica, which was in May 1775, the cafe became too {mall 
for the inftrument, it was with much difficulty and vari- 
ous contrivances that I got it out, and I could never after 
get 
