mBke FarofcopUal Ohterv^tions in feveral parts o£ England {\i 
not in forrain Countries alfo j J 
* Some v^kreofhAve heen ftnce ^od to alEft them, to do fo, prefcn^ 
•Si^itS^I^Si"'"' of my Friend, „i,h the 
neceffary Inftruments : The decla- 
red reafon of my defiring this Correfpondence was ( among 
other things) that by comparing Notes, the Extent of the At* 
mefpherical Chanoes , in point of Weight, might be the better efti-* 
mated. But not having hitherto received fome account^ 
that I hoped fofj I lhall now, without ftaying for them,intimatc 
thus much to you: That it will be very convenient, that the 
Obfervers take notice not only of the day 5 but, as near as they 
can 5 of the Hoare wherein the height of the Mercurial Cylinder 
is obferv'd: Bor I have often found, that within lefs than the 
compafsof one day, or perhaps half a day, the Altitude of it 
has fo confiderably vary a, as to make it in many cafes difficult, 
to conclude any t^hing certaiQly fram Ohferv^tipjis-, \ that agree 
but in theday. \ .^^i,^ ,.,. 
It wiil berequifite alfo, that the Obftr vers give notice of 
the Scituation of the place ^ where their Barometers ftand, not 
only, becaufe it will affift men to Judge, whether the Inftrur 
Bientswere duely pcrfe(9:ed, but principally , becaufe, that 
though the B^2r<?/ro/^5 be good ( nay, becaufe it is fd ) the Ob- 
fervations will much difagree^ even when the Atmofphere is 
in the fame ftate^ as to Weight , if one of the Inftruments 
ftand in a coi>fiderably higher part of the Co.untrcy, thaa thb 
other. 
To confirm the foregoing admonitions, I muft now in- 
form you, that, having in thefc parts two Lodgings,thc one ac 
Oxford, which you know ftands in a bottom by the Thames fide, 
and the other at a place,four miles thencCjleated upon a mode* 
raiG MiH, 1 found, by comparing two 5<«ro/?o^ipj', thkt I made,, 
the one zt Oxford, the other at Stanton St. 5^^)&;2/,that5though thfe' 
fermer be v-ery good, aud have been noted for fuch, during' 
fome years, and the latter was very carefully fiU'd 5 yet by- 
reafon, that in the Higher phcc^ the incumbent part of the^^- 
mofphere muft be lighter, than in- the Lmer^ there is almoft al- 
ways: 
