The Microscope. Its History, Construction, and Application 15th ed. / Being a familiar introduction to the use of the instrument, and the study of microscopical science

by Jabez Hogg

COVER-GLASS GAUGE.

Zeiss has gone a step further to lay the microscopist’s ghost of the cover-glass. He invented a measurer ([Fig. 121]) whereby the precise determination of thickness of glass-covers can be obtained. This measurement is effected by a clip projecting from a circular box; the reading is given by an indicator moving over a divided circle on the lid of the box. The divisions seen cut round the circumference show ¹⁄₁₀₀ths of a millimeter. This ingenious gauge measures upwards of 5 mm.

This necessary and important digression has led me away from the consideration of the achromatic objective, and to which I shall now return.