fcerned far fmalfer Alterations of the Weight of the Air,fince 
I had the pleafure to fee the Bubie fometimes in an (equilibrium 
with the counterpoife , fometimes, when the Atmofphere was 
high, preponderate fo manifeftly, that the Scales being gently 
/v- > i ^ r»n fbnt firlfr . at which 
ftirr’d, the Cock would 
on that fide , at which 
the Bubie was hung ; and at other times (when the Air was hea- 
vier) that, which was at the firft but the Counterpoife , would 
preponderate, and, upon the motion of the Ballance, make the 
Cock vibrate altogether on its fide. And this would con- 
tinue fometimes many daies together, if the Air folong re- 
tain’d the fame meafure of gravity • and then (upon other chan- 
ges)the Bubie would regain an (equilibrium ,or a preponderance; 
io that I had oftentimes the fatisfa&ion, by looking firft upon 
the Statical Barofcope (as for diftiinftions fake it may be call'd J 
to foretell * whether in the A/mmW Barofcope the Liquor 
were high or low. Which Obfervations though they hold as 
well in Winter, and feveral times in Summer ( for I was often 
abfent during that feafon) as the Spring , yet the frequency of 
their Viciflitudes (which perhaps was but accidental) made 
them more pleafant in the latter of thefe feafons. 
So that, the matter of Fad having been made out by variety 
of repeated Obfervations, and by fometimes comparing feve- 
rall of thofe new Barofcopes together, I fhall add fome of thefe 
Notes about this Inftrument, which readily occur to my me- 
mory, referving the reft till another opportunity. 
And Firft , if the ground, on which I went in framing this Ba* 
rofiepe , be demanded, the anfwer iirfhort may be j i. That, 
though the Glafs-buble, and the Glafs-couaterpoife, at the 
time of their firft being weighd,be in the Air, wherein they both 
are weigh’d, exactly of the fame weight ; yet they are nothing 
near of the fame bulk i the Bubie, by reafon of its capacious 
cavity ( which contains nothing but Air, or fomething that 
weighs lefs than Air ) being perhaps a hundred or two hundred 
times ( for I have not conveniency to meafure them ) bigger 
than the Metalline counterpoife. %. That according to a 
Hydroftatical Law ( which you know I have lately had occafion 
to make out) If two Bodies of equal gravity, but unequal bulk 
come to be weigh'd in another Medium , they will be no longer 
li 2 
