Microscopic Measurements

Abstract

IN elementary biological classes the measurement of microscopic objects is useful for training in accurate observation and for the intelligent use of the various parts of the microscope. In this connexion it may be pointed out that the estimation of the vertical distance between objects in microscopic preparations helps greatly in the realisation of solid forms and of the information which may be obtained from superimposed optical sections. The estimation can be made very simply by the use of a microslip carrying on one side a short line of transparent red, and on the other a similar line of green, glass ink. The lines cross each other and form an ‘X’ when one looks vertically through the slip. From the thickness of the slide at X, ascertained with a coverglass-micrometer, and the number of revolutions of the milled head of the fine adjustment of the microscope, which are required to pass from the level of the focus of the red to that of the green line, the pitch of the screw and the value of the movements of the fine adjustment are obtained.