C 1808 ) 
f^acua, the Mercury then in the Gage (landing at 29 inches 
h i Upon dropping the firft quantity of Powder, ( by 
a quantity is to be underftood fomcthing more than a 
Grain weight) its Explofion made a Defcent of the Mer- 
cury in the Gage about an Inch, undulating very little. 
The fecond quantity being let fall^ the Mercury fubfided 
about ^of an Inch 7 and !fo fdr fci'eral qaantities foHov/- 
ing it defcended by pretty ecl^ii^rStages, till it had fain 
about 6 or 7 Inches ^ and it was obferv'd, upon every 
quantity fir*d, the Undulations of the Mercury jn<?reas'cL 
But > rfter it h^^^ fubfided 6 01: 7. Incht:sJrOrB^i? ^ nthal 
feWt-aldefcents of it i became kftv vei.yj liitle or upthihg;^ 
e^irfeeHteg i aii Inchf ialtho the Quantities fir'j wt-re equd 3. 
but ftill the Undulations encreas'd, and the Explofioqii 
Bfcanifeftly did fo too ; Till at laft thcRjeceiver feem'd Ip-^ 
l^ingrcat da^nger of being blown up by a Ht^gle Quantity, 
the ttnd ulationk of the. Mercury b4ingt]he;n augrqentedlQ 
i or 7 hichesi - Ni^vv 26:cQuantitifs' -or-gi2 Orpins hayjog 
been fir'd upon the Iron, and the Mercury in the Gag^ 
fain to 1:2 ^0 I diligently attended to obferve the Gage, 
which in 7 minutes had afcended 2 Inches I, the next 5 
minutes it aroTe but'once Irjch and fo left fUcceffively 
every 5^ minutes, that in an hour and 17 minutes it had' 
attain-d bur to ^ i vjpcheg^ th^e,Irop. nqt being quite cc^d. 
At 9 the fame nigi;it I ob(erved thVdage, and found the 
Mercury elevated to a jlrfclies^q:, precifc^ mom at 
9 it had attaitfd ib 22 r, and i?ivContintfd air that day, 
the Iron then being reducd to the tetiiperjture of the 
outward Air. So that from 12 4 to 21 i feems to be the 
weight or fpring of heat equal to about f of an Atmo-^ 
fphere of Air, whiA; would prefs the Mercury upon the 
upper part of the Gag^, but equal to fiich a degree of 
heat as was then^opmain d infj; the Receiver^ _^^'heiji thp 
Gage was fain tt^nM7l ii Tile j^maining fpace. fiyon^ 22^^ 
Jb 29-2: is luppbsy to betfiilpf%f4 aiid 
a^twers^ to about Cf>^ p€ ihe^ Recipients whole C^on- 
tent^. 
