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the glafs tube is fufpended in it, 
BB, the brafs dcale of three Paris 
inches divided into an hundred parts, 
CCCG, the giafs tube or great 
meafure, whofe lower and open ex- 
trémity is fecured by a brafs ferrule. 
D, the magnifier for the more c= 
curate obfervation. 
Fic, II. The fmall tube or mea- 
fure fixed in its brafs fotket. <a, is 
ar élaftic- piece of brafs, having a 
pin paffing through a hole in the 
under part of the focket, which 
pin is pufhed upwards by the elaf- _ 
ticity of the piece a, and enters in — 
a cavity’on the under fide of the 
flider, made -on purpofe to ftop it, - 
and to prevent the bended feel 
{pring from forcing the ilider en- 
tirely out of the focket. N.B. Ithink 
“3 
= ae faker may da’ very well *é 
| <2 oo Swithour® 
