C 540 3 
faften'd there with Soder^ the Axis 4^: laid Parallel to the Plate 
ddd,.2j[id about an iach and half abave it» - The Perpendicular 

End of the Cylinder DC was dos'd with an Objed Glafs of a 
j6th. Foot Telcfcope, 00-, and the other End AB, with a well 
polifht flat Gfafsj^j which was carefully chofento tranfmitthe 
Objed diftind enough notwithftanding its Obliquity to the 
Vifual Rays. The Ferule* were well fill'd with Cement round 
about the Edges of theGlafs, and they laid flat^d eye/^ 
where toucht the fmooth Ends of the Cylinder , that they 
might firmly refift the preflTure of the Excluded Air. 
Inftead cf a Ciftern (as in the Torricellian Experiment) 
we made ufe of the Inverted Siphon of Brafs Fig, U. MNO, 
fbdcr d to the Plate g^^. One of the fides MN ftood Perpc;i» 
dicular to the plate, and the other fide NO Enclin'd to it , and 
was fupported near the upper End O with a little prop k,!^. 
We then placd the Cylinder (as in Fig. III.) upon a Table 
which was wellfaften'd to a firm Flore ; The pipe GH was lei 
through a Hole , and the Axis laid alraoft parallel to the fides 
of the Table, and the Plate tl^id was nail'd down to it. The 
Tube of the Telefcope f f with the Eye glafs was apply'd to 
the Objedt Glafs, and a Hair fixt within it at the commdn 
Focus of both glaffcs in the Axis of the Cylinder continu'd, x. 
Upon thefloore (under the Cylinder ) we nail'd the plate ^j^^ 
with the inverted Siphon upon it , and joined M to H by the 
Infection of the Glaft Tube T. The joints were very carefully 
clos d with Cement : And then they were cover'd over with 
pieces of a bladder and wrapt hard with ftrong thread. There 
was alfo a bladder ty'd below each ;oint at and when it 
was fill'd with Water it was ty'd above it at 9; So that no 
Air could come to the Cement or infinuate it felf through it'f 
pores orfiffures if any happen'd to be left unclosed. 
It is not C I think) an unneeeffary trouble, that in this 
account of the Apparatus I have roention'd fo many minute 
Circumftances , for we found it difficult enough to exclude the 
Air , and aimoit Impoffible to difcover the very little holeg 
through which (b fubtil a fluid would freely enter and pof- 
fefs the fpaces defertedby the fubfiding Mercury. But with 
all this precaution the experiment fuccceded at laft, as i wiflit^ 
after this manner. 
We plac d the ObjcCt d ( which was a black thread Aiding 
in a little frame over a piece of white paper) in the Axis of 
the Cylinder ex continud to it % We SXfd the Pipes and Cy- 
^ i ,. Mil i^, Hi** -flind^r 
