76 
The latter two with double divisions, English measure 
and mm, each 
Fully divided Circles on plate-glass discs, with centre 
marks, for use as transposers : 
Circle 80 mm in diameter, Vi degrees 
Circle 120 mm in diameter, degrees 
Goniometer Eye-piece (No. 2), for estimating the angles 
of microscopical objects, with divided circle and glass plate marked 
with a series of parallel lines; sliding adjustment to eye-lens 
Cover-glass Gauge for the exact measurement of thickness 
of cover-glasses, thin plates etc. — The measurement is effected by 
a clip projecting from a box; the reading is given by an indicator 
moving over a divided circle on the lid of the box. The divisions 
show hundredths of a millimeter. Measures to upwards of 5 mm. 
Fig. 34. 
Cover-glass Uauge. No. 41. 
42 
Cover-glass Gauge of simpler construction ; screw with 
divided disc and arrangement for regulating the pressure; rends 
O.Ol mm 
13.— 
