Fig. 59.—Ross’s “Bacteriological and Histological” Microscope.
The amount of activity shown during the last few years by opticians in the manufacture of new forms of microscopes renders it somewhat difficult to keep pace with improvements, some of which are novel. A further source of congratulation is that economy has all along been studied; so much so, that the instruments in question are within the reach of persons of moderate means. Messrs. Ross and Co. have taken a new departure in this respect, and their “Eclipse” Microscope is an entirely new form of stand with a ring foot. This microscope has been produced for the especial use of students, and can be purchased for a moderate sum. It will be seen at a glance ([Fig. 60]) how steady this form of stand must necessarily be, since the centre of gravity is secured in every direction and inclination. The body-tube carries eye-pieces, numbered, of the Continental size and optical tube-length (160 mm.), for which the object glasses are adjusted, and a draw-tube extending to eight inches.
Fig. 60.—Ross’s Rigid Pattern “Eclipse” Microscope.
The fine adjustment is independent of set screws, and not subject to derangement. It is extremely sensitive and direct in action, and from its construction is equal in perfection of working to the best that can be made. Its fitting, by a new contrivance, is completely covered at all points, being thus preserved from disturbance or injury by dust.
The Eclipse is furnished with two eye-pieces, 1′′ and ¼′′ object glasses of highest excellence and large angular aperture, both adjusted to a double nose-piece, so that they focus in the same plane; and a swinging mirror and stage iris diaphragm.
In “Wenham’s Radial” Microscope the chief aim has been directed towards providing a very considerable range of effects, both in altitude and azimuth. The leading principle followed throughout in the construction of this form of stand is that of facilitating the work of the microscopist and of obtaining the maximum range of oblique illumination in all directions. This is fairly well attained by causing all the movements of inclination and rotation to radiate from the object as a common centre. Thus it has been found possible to combine seven radial motions, so that when the instrument is inclined backwards, as in [Fig. 61], or placed in the horizontal, as in [Fig. 62] or rotated from in the brass plate, a pencil of light from a fixed source shall always reach the object and pass to the objective. The stage is made to rotate completely, and its rectangular motions are effected by milled heads acting entirely within the circumference. The sub-stage is mounted on the Zentmayer system, with two centring screws, by means of which the optic axis is secured. It is also provided with rectangular and rotating motions. The coarse adjustment is that of the Ross-Jackson form—a spiral pinion and diagonal rackwork, while the fine is on an entirely new principle designed by Dr. H. Schrœder.
Fig. 61.—Ross’s Wenham Radial Microscope.