Excerpt from Illustrated Price List of Microscopes, Microscopic Apparatus and Other Optical Instruments, Manufactured by R. And J. Beck, LondonThe Binocular body consists of two tubes, the one fitted in the optical axis of the Microscope, and the other oblique. At their lower end and immediately above the object-glass there is an Opening, into which a small brass box or fitting (i) slides, this box holds a prism so constructed that when slid in it intercepts half the rays from the object-glass, diverts them from their direct course, and re¿ects them into the additional or oblique tube. To the prism-box is attached a spring-catch, which, when pressed in, permits of the removal of the prism box, but this is only needed for cleaning, as, when the box is drawn back to the distance allowed by this spring, the prism in no way interferes with the field of View, and all the rays pass up the direct body, and the Microscope is converted into a Monocular one.The upper or eye-piece ends of the tubes are fitted with racks and pinion for varying the distances between the two eye-pieces, to suit the differences between the eyes of various persons, and arrangements are made for racking out one tube more than the other, to suit irregularities or inequalities between the eyes of the observer.About the PublisherForgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.comThis book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully, any imperfections that remain are intentionally left to preserve the state of such historical works.