OF THE MICROSCOPE. 3? 



stead of joining the body at aright angle, as in the Ross mode), 

 and many of those made after the so-called Continental pattern. 

 The special advantages of this model are great steadiness and 

 the fact that in common with the form next to be described, it 

 affords abundant room underneath the stage for those accessory 

 methods of illumination which are indispensable in the highest 

 class of work. It is almost impossible to attach to the smaller 

 patterns of the Continental model a convenient sub-stage, carry- 

 ing polarizer, achromatic condenser, paraboloid, etc., while the 

 model under consideration is specially designed to receive these 

 important accessories. 



Tiie Ross Model. The distinguishing characteristic of 

 this model is the mode in which the body is supported. By re- 

 ferring to Plate III, it will be seen that the body is attached at 

 its lower end to a transverse arm, which in turn is supported 

 by a stout bar, which is moved up and down by means of a rack 

 and pinion. This movement constitutes the coarse adjustment, 

 the fine movement being effected by means of a lever which is 

 concealed in the transverse bar, and acts upon the nose-piece. 



So far as mere questions of convenience and adaptability to 

 different kinds of work is concerned, this model is all that can 

 be desired, and as made by Ross & Co., the workmanship is so 

 perfect, and the finish so exquisite, that it has long maintained 

 a high position in public favor. It has, therefore, had numerous 

 imitators, and has probably been copied more extensively than 

 any other model in existence. At the recent Centennial Exhi- 

 bition there were microscopes on this model from the most 

 widely scattered localities. Canada was represented by two 

 microscopes made after this design. Unfortunately, however, 

 this model is one of the very worst that a poor workman can 

 attempt to imitate, for unless the workmanship is far above the 

 average, the results are execrable. The reason for this is 

 very obvious. The body, being supported only at the lower 

 end, every vibration causes the upper end to swing through 

 a comparatively large arc, and hence any motion arising from 

 looseness in the joints is multiplied a hundred fold. And even 

 when the joints are firm and without shake, any vibration com- 

 municated to the table on which the instrument stands, is 



