piece ED moving round' abobt the Center i?-, by which ra 
ih^ Sight mny beremov'd either towards R or F. 
EF is 2 RmU hAndon to the two Rulers GGy which Rulers 
fcrvc both to keep the fquire Frame SSSS perpendicular^ and by 
their Aiding through the fquare holes TT'j they ferve to ftay the 
5/^k,either farther from or nearer to the faidFrame-, on which 
Frame is ftackon with a Httle wjix the paper 0000^ whereon 
the Piflure is to be drawn by the Pen I, This Pen I. is by a 
(mdWBra^'handle r.fofixc to the Ruler BB, that the point I, 
may be kept very firm, fo as alwayes to touch the Paper, 
HH, is a Ruler , that is ahvayes, by means of the fmall 
{kmp aaaahhb.by mov'd HorizontalljtOi Parallel to it felf ; at 
the end of which is ftock a fmall Pin^whofe head P is the Sights 
which is to be mov'd up and down on the out-lms of any 
Objed, 
The Contrivance of the Strings is this. The two Strings 
aM, bhh, are exadlly of an equal length. Two ends of them 
are faftnd into a fmall Leaden ^^ig^^ ^^which is mov'd in a 
Socket on the back fide of the Frame, and ferves exadlly to coun- 
terpoife the i^/z/^r^Z/j being of equal aw^i^^ with it. The other 
two ends of them are faftn d to two fmall Pins H,B^ after they 
have beenroled about the fmall Pnlkp N,MM. LL. KK^ by 
means of which Pulleys li the Pen I. be taken hold of and mov'd 
yp and down the Paperj the Strings moving very eafily^ the Ruk 
will always remain in an Hmzontal^ofnion. 
The m inner of Uiing it is this : Set the Infirument on a 
Tableland fix the Sight A, at what height above the Table^ and 
at what diftance from the Frame SSSS^ you pleafe. Then^ look- 
ing through the Sight y^^and holding the Pen I, in your hand, 
move the Head of the Pin P. up and down the Out-lines of the 
X)bje<a5 and the point 1. will defcribe on the Paper. GOOO, the> 
Shage of the ObjedtXo traced. 
