DE W.. 
‘rough; for he fourid that niuch dew fell upon what tie calle 
fe Hee afperum, and plumbum ae ro Neue: fe tu i 
ru 5 
It. Mr. ne ‘Fay, at Pats: made’ the. following exneri- 
ments.” He placed a oo faucer in the 
plate, and ee ng t 
its middle:a filver dith, eae refemblin ing: tl 
faucer. I this he expofed to the peaieos air, and foun 
that the china fee was ee with déw, whilit the fives 
plate, which extended four inches round it, = net moiftened 
in the leaft. Alfo the china plate was covered’with @ con- 
fiderable aad of dew, whilft the filver difh in the middle 
of it was quite 
Fa ays in order to determine whether the nature 
velle lace ive: the 
was furrounded ae a filver ferril, the nee ota which was to 
prevent any a of dew. to i ‘furface, whi 
aced the filver ane, his apparatus dn tae been’ expofed 
= feveral fucceflive nights, he conft fou 
principally abor 
— dim Jinithed i in fize 
from the centre, and le 
gait dry all round the oe ar the g¢ 
7. Dr. Watfon, bifhop o ners “ie foie: ‘experie 
ments performed by himfelf, the refult of which coincides 
with that of pe prec = paragraph. ‘ By means,” he 
fays, “of a e bees-wax, I faftened a pales very 
near, but not aie ecaugions to the fide of the glafs ; and, 
fetting the glafs. with its mouth downwards on the grate, it 
prefentiy became covered with vapour, except that part of 
it which was har the half-crown., Not only the ee 
e from vapour, but it had hinder d any 
_ on cane giafs whieh was near it ; ae: was a ie 
ing of glafs ie candine the half-crown, ie the ofa 
a of an inch, which was quite dry, as aa as aia part 
of the glafs which was immediately under the half-crown ; - 
feemed as if the filver had repelled the water to that diftan 
e effect as: the iaiecceas ie 
the form 
tuation was. more r 
be . pea to enumerate 
A mueh more ex She feries of experiments on this 
fue the ok of which is ed yee Fs of ogi 
as a few years ago inftitute ts fu 
s foll He found ca when plates- of 
when the other fide of the glafs is expofed to 
which is oppofite to the a remains perfeGly dry. Ifthe 
be again covered w h glafs, it will lofe i “effe@ in 
e 
ee the depofition. : 
, - Thefe eget imedter may be very conveniently made on 
ae glaffes ‘of : felons when moifture is attaching itfelf to 
either of its {urfaces. remarks that it often 
plat fixe 
: oe on-a window, soci a ‘a larger quantity at meifture 
« 
ord : bout half. hy. 19. 
er ale taal ne Mr. Pr on . “that. when 
han ’ Blals;: stile the aes oppofite to an 2 external plate 
-g and ifthe humidity 1s depofited. from a 
he vince pears che internal plate is alfo more moiftened, 
while us external penta remains dry-; oth thefe cireum- 
with the fame refult. A {mall 
ducé8.again a cen 
ae ae ee ye cae 
ot eee until. ae. ae chcknel eee half. ai an 
re Gilt. paper, with its. metallic ne expoled, acts 
asa metals oa sii the: pepe only is expofed, it has no 
effect. 
ae ch plate of metal, on which moifture would have 
been ‘aepiiited 13: fixed. at a fmall: aiftanee from: the glafs, the 
moifture is tranéfette to the’ furface ¢ of the glafs ‘rnmediately 
u  the-ar If this plate is’ vara 
e fuiface remote. froin the glafs, the effect re- 
mais; hut" 5P on the fide nekg the “glafs, it is deftroyed. 
"78: Phe: ox ydation’ of ‘metals renders them alfo unfit for 
é , are expofe 
pofited only ig Feneipart which ‘are above the furface of the 
fluid. But in ail cafes when the baa is too sg 
the refults are-cGafu ed.” 
order, to, speduee ‘thefe facts to. fome general law, 
the meta {"is placed on the 
war mer. fide of the glafs, the humidity is depofited more 
ioufly either on ee or on ae furface of the glafs in 
its peathoue urhged 5 bu wkhat w ‘na it.is on the colder fide, 
it. neither receives aes lity, or permits its pie on 
the , glafs, “hat: a coat of g rnifh deftro 
efficacy of the metal, but that a an. “additional plate oe feel 
oe 
. The quantity of water which falls upon the furface ‘of 
de. ea arth i in the form of dew, has s:by no means been afcer- 
than the dew that falls in the nig ei s near 
26 ounces from a circular area of a foot diameter. If 180 
grains of dew, falling in.a night on fuch an area, h is 
whic 
113 fquare inches, be equally a: on the Gres, 
180 
equal to 
its depth will be 25th part of an inch, a 
—. 
He likewife found the depth of dew in‘a winter’s night to 
be the 
3-28 inches depth. But the quantity, w 
srapontel in a fair fummer’s day from the fame fur ee 
8 ‘ein 
5 
bp 
