Fig. 79.—Students’ Petrological Microscope.
A polariscope having prisms of large size is supplied with it, the analyser being fitted in the body, and the polariser in the under-stage fitting. The latter has a divided circle and a spring catch at every quarter circle. By removing the polariser and withdrawing the analyser, for which provision is made, the microscope can be used for purposes of ordinary research. A Klein’s quartz plate is fitted beneath the analyser, also in the body of the microscope.
The stage, which has a glass surface, rotates concentrically, and has a divided circumferential edge reading by the verniers. The eye-piece has cross webs to the diaphragm, and when it is desired, an analyser, having a divided circle fitted with a calc-spar plate, can be used above the eye-piece, and condenser lenses attached to the polariser for stereoscopic purposes. All the fittings have the universal thread, and are interchangeable.
Fig. 80.—Swift’s Histological and Physiological Microscope.
Messrs. Swift’s Microscopes.
Messrs. Swift’s Microscopes have a well-established reputation for quality and good workmanship, and therefore can in no way suffer by comparison when placed beside those of other opticians. One of the characteristics of Messrs. Swift’s microscopes—and this runs through the whole series—is that they are all made to a standard gauge, so that the several parts of the instruments, as well as their accessories, are interchangeable; the cheaper forms, with those of the first quality and finish. Should the student, then, start with a No. 1 model, he can at any time build it up, as it were, with the accessories designed for a No. 3 or 4, that is, for an instrument of double the price he started with. The optical centre is preserved throughout the whole series of microscopes.
Fig. 81.—Swinging Leg Attachment of Swift & Son’s Four-Legged Microscope Stand.
The tripod foot has, it appears, taken the place of some of their other forms of instruments, while their four-legged tripod, if it can be so designated, is a novelty of quite an unusual character.