I 
[^49] 
^latc is concave, is grounded upon no necfefflty 5 but 
lince the ftrudture of the internal parts will very wel 
admit of fuch a figure , and it comported pleafingly 
with a fancy I had of rendering the front of the Move- 
ment more beautiful , therefore currente rota ( as the 
Poet fpeaksj l gave liberty to my penfil to defcribe 
it in this manner. But if the hemifphere with the fi- 
gure thereon, {hall feem a piece of work too elaborate 
tor the end it ferves unto,- and for the fake of which 
the Dial-plate is form'd into that fhape : I have {Fig. 4,) 
drawn a plain which you may fubftitute in he 
roomthereof,or any other, (as it (hall pleafe the Painter) 
provided that the Axis whereon 'tis lopported, move 
freely in the hole [H)i and the lower part thereof H. 
/. may fo far preponderate to as always to keep 
the Index pendulous, with its point to the vertical 
hour. 
2. For the manner of its motion, as far forth as it 
appears outwardly, it is thus; 6". EyFig^. i. reprefentsa 
board or fhelf^ of a flrait and even furface, about 6 foot 
long, and lo thick as not to be apt to call with change 
of weather ; nor to grow Camber under a fmall weight s 
on this is the Movement plac d and here to perform its 
courfe, and therefore I call it the Stage of the Movement, 
This Stage is rais'd at the end S. about lodegr. above 
the Horizon or line of level H.E-^ but the Angle ^of its 
declivity D.E.H. is variable, as will hereafter appear i 
and although it happens in the Scheme to be 10 degrees, 
yet I would have it underftood to be indefinite at prefent, 
till I come to fhew the caufes that will determine its 
quantity. The 2 plates which form the Cafe of the 
Movement, are to be extant all round without the hoop 
{h.) iofan inch, and the edges of 'm lightly indented 5 
t\i2it'^\vXtl\iQ, Movement deicends upon the it may 
turn only, and not Aide. 
3. The ufe thereof in meafuring time, is as follows. 
Movement h^m^ placYi as high as it may, near the 
point (S,) fliall move downward towards with that 
I 2 flownes 
