Angular Model Microscope.

This microscope is of a new and original type. The design renders it possible to embody new and striking features which make it a universal instrument suitable for almost every kind of work both visual and photographic, with a maximum degree of ease of manipulation and comfort in working.

The rigidity obtained by fixing the body on the combined limb and base of the instrument gives a freedom from flexure and vibration not hitherto reached with the ordinary forms of microscope. This gives a great advantage not only for photography but for observation with high powers or for the examination of objects in fluid.

With the ordinary microscope the operator finds considerable discomfort when the instrument is vertical, but with the Angular microscope the body is inclined at a convenient angle, so that he may be in a natural position when working.

The stand itself is always vertical and the stage horizontal, so that fluids or specimens in liquid can be placed in troughs or dishes upon the stage. A further advantage of the stage and substage being kept in a horizontal position is that the immersion fluids of an oil immersion object glass, and more particularly of a dark ground illuminator, have no tendency to run.

The method of interchangeability of the various bodies and the photographic camera is an important improvement. They fit by means of a dovetailed slide in the top of the main limb casting, giving complete rigidity in fixing, but can be changed with great rapidity. A specimen can be examined either with the monocular or binocular body, or when the combined monocular and photographic body is in use the camera can be instantly slid into the optic axis and a photograph taken without refocussing or disturbing the adjustment of the microscope.

The focussing adjustments do not operate upon the bodies of the microscope or upon the slides which carry them. The weight of these is taken direct upon the limb and base of the instrument. The fine adjustment operates only a collar carrying the object glasses, so that no undue weight is carried by the fine adjustment, and an extremely efficient motion is obtained. The coarse adjustment moves the stage and its focussing slide has a clamp so that it may be regulated or actually fixed. These points are of the greatest importance in photography, obviating any tendency for the focussing adjustments to settle during a long exposure.

The binocular is of the most efficient type, suitable for use with all powers and having its tubes inclined to each other at the correct angle of convergence as described on page 45. It is provided with adjustment for the accurate setting of the interocular distance. It gives the greatest comfort in working and the definition given is critical.

The angular microscope, beside having the advantages referred to for ordinary work and for biological or medical research, is specially adapted for use with all forms of opaque and vertical illuminators. With such illumination it is desirable to fix the illuminating system, which is possible with this microscope, the focussing being effected by movement of the stage. Where research

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