( »op? ) 
and my felf, the Redangle E H G, wherefbever taken, 
proved always equal to it felF, to as great an accuracy as 
could be expeded, when the Planes were opened to any 
confiderable Angle : But when the opening was very 
fmall, the inequalities of the Planes, though the bed f 
could procure, bearing a greater proportion than be- 
fore to the diftance between them, occafion’d a fenfi- 
bie variation. Which, by the way, 1 take to be the 
reafon, why the Ordinates found by the late Mr Huivks’ 
ke, in examining the Curve produced in a contrary (i* 
tuation, upon dipping two Glafs Planes fo join'd into 
5p)rit of Wine, do not anfwer to thofe of the Hyper- 
bola. 
Exp. IV. Fig> 8. A B is a perpendicular Sedion 
through two Glafs Planes join’d at A, and open’d to a 
fmall Angle at B. C reprefents a pretty large drop 
of Mercury, the larger the better, which being made 
to defcend as far as C, by holding the Planes in an e- 
red pofture, with the end A downwards, retires from 
the contad of the Planes to D, upon inclining the Planes 
towards an horizontal Situation ^ and the diflance C D 
becomes greater or lefs, as the Planes are more or lefs 
inclin’d towards the Horizon. 
A drop of any Oily or Watery Liquor moves the 
contrary way, as has been fliewa by the late Mtr Hawks- 
hee. 
Exp. V. Fig. 9. A B is a Tube open at both ends, 
and a Foot or two in length, whofe lower part is 
drawn out into a fine Capillary at Bi This Tube being 
fill’d with Mercury, the whole Column of Quickfilver 
will be fufiain’d in it, provided the Capillary Tube 
at B be fufficiently fmall. But if the Mercury in the 
end B be fuffer’d to touch any other Mercury, it runs 
all out of the Tube if, without letting it touch any 
other Mercury, a fmall part of the end B be broken off, 
I o F X the 
