MicROGRAPHIA. 
‘I had feveral other Tables of my Obfervations , and Calculations, 
which [ then made; but it being above a twelve month fince I made 
them and by that means having forgot many circtmftances and par- 
ticulars , I was refolved to make them over once again, which I did 
908 
Auguft the fecond 1661. withthe very fame Tube which Iufed'the year 
before, when I firft made the Experiment ( for it being a very good 
_ one, I had carefully preferv'd it: ) And after having tryed it over and 
_ Over again; and being not well fatisfied of fome particulars,’ I, at laft, 
having put all things in very good order, and being as attentive, and 
obfervant,, as poflibly | could, of every circumftance! requifite to be tax 
ken notice of, did regifter my feveral Obfervations in this. followin: 
Fable. In the making of which, I did not exactly follow the Madthod 
that bhad ufed at firlt ; but, having lately héard of Mr. Tows#ly’s Hypo- 
thefis, Uthap'd my courfein fuch fort, as would be moft convenient for 
the examination of that Hypothefiss the event of which youhave in the | 
lnttérpareof thé lat Tables: corer) vd belod. 
The other Experiment was, to find what degrees of force were requi- 
fite to comprefs, or condenfe, the Air into fuch or fuch a bulk. 
The manner of proceeding therein was this: took a Tube about 
five foot long, one of whofe ends was fealed up, and bended in the form 
of a Syphon , much like that reprefented in the fourth Figure of the 
37. Scheme, one fide whereof AD, that was opén at A, was about fifty 
inches Jong, the other fide BC, fhut at B, was not much above feven in- 
ches long; then placing it exa¢tly perpendicular , ¥ pour in,a little 
Quickfilver, and found that the Air B C was €3 inches, or vety nearto 
feven ’; then pouring in Quickfilver at the longer Tube, I continued 
filling of it till the Air inthe fhorter part of it was contracted into half 
the former dimenfions, and found the height exaly nine and twenty in- 
ches; and by making feveral othertryals, in fevetal other degrees of 
condenfation of the Air, I found them exactly anfwer the former Hypo- 
thefis.. : ) : een 
Ee. ut having (by reafon it wasa good while fince I firft made) forgot- 
ten many particulars,and being much unfatisfied in others, I made the Ex- 
_ periment over agaifi, and, fromthe feveral tryals, collected the former 
part of the following Table : Where in the row next the left hand 24. 
figniffes the dimenfions of the Air, futaining only the pretiure of the At- 
mofphere, which at that time was equal to a Cylider of Mercury ‘of nine 
and twenty inches: The next Figure above it (20) wns chee 
-_onsof the Air induring the firft compreflion, made by a Cylinder of Ader- 
cury 5%, high, to which the preflute of the 4rmo/phere nine artd twenty 
‘inches being added s the elaftick ftrength of the Airfo compreft will be 
found 34%, Gc. : 
4 
Hh - A 
ae 
