45 Mr. SMit ATONES Obfervailons on the 
be turned in the place where the divifions will come, that any 
conical pin, that is to ferve as an index, let drop into the divi- 
lions or holes, may not, by reaching through this thin plate., 
abut upon the wood, rather than upon the fides of the holes t 
and thus this hoop is made into a wheel of 1440 equal divi~ 
lions, moveable round upon its own axis, whereon it was 
formed. 
Againft the time that this is compleated, there muft be pre- 
pared a flat circular plate or wheel of brafs, the rim of which 
ihould be of about 3I inches breadth, and about two-tenths of 
an inch in thicknefs when finifhed, to make a dividing plate.; 
the external diameter of this is to be fuch, that when laid flat 
upon the furface of ithe mahogany platform, its extreme edge 
will exceed the diameter of the hoop by about half an inch all 
round* There muft alfo be prepared brafs arms (fuppofe eight in 
number) of an equal fubftance with the outer rim, and all con* 
ne&ed with a circular plate in the middle ; and, the whole of 
this work being framed beforehand, is to be let on flat upon the 
mahogany platform ; whofe face is fuppofed to be turned truly 
flat, and fufficiently affixed with fcrews : in this fituation, the 
outward edge is to be turned, and the outward face of the rim 
turned flat. The center plate , which may be about twelve inches 
diameter, is alfo to be turned as flat as poffible, and a center 
hole, of about half an inch diameter, to be very carefully turned 
therein. 
A piece of clean, ftraight-grained, wellfeafoned mahogany, of 
about two feet long, three inches thick, and five or fix inches 
broad, is then to be well , affixed to fome part of the general frame 
of the lathe, which muft now have its pofition altered, fo that the 
platform will become horizontal ; and therefore the frame fhould 
be 
