[ 6o8 ]• 
References to the Figures. 
Fig. i. represents the instrument independent of the 
cittern in which it is us’d. 
ABC D y is the main bar or bafis of the inftrument. 
E F, is the bar to be meafur’d, lying in two notches j 
one fix’d to the upright Standard A B, the other to 
the principal lever H I. The end E of the bar 
E F, bears againSt the point of 
Gy a ferew of ufe in examining the micrometer- 
ferew. 
The other end of the bar F bears againSt a fmall 
Spherically protuberant bit of hard metal fix’d at 
the Same height as G, in the principal lever H I. 
K, is an arbor fix’d in the bafis, which receives at each 
end the points of the Screws HL , upon which the 
lever H L turns, and Serve as a fulcrum thereto. 
O, is a flender Spring, to keep the lever in a bearing 
ftate againft the bar ; and 
P, is a check, to prevent the lever from falling for- 
ward when the bar is taken out. 
Nj is the feeler, Something in the Shape of a T, fuf- 
pended, and moveable up and down upon the points 
of the Screws I M> which, as well as L H , are So 
adjusted, as to leave the motion free, but without 
fhake. 
v. is the handle of the feeler, moveable upon a 
loofe joint at R ; So that, laying hold of it at 
the feeler is mov’d up and down without being af 
fedted by the irregular preffure of the hand. 
The extremity s of the feeler is alSo furnifh’d with 
a bit of protuberant hard metal, to render its con- 
tact 
