416 Notes. 



The instrument is the joint invention of Messrs. Ashe and 

 Finlayson, and was designed to suit the special requirements of 

 the latter in his examination and comparison of food materials, 

 meals, starches, and fibres ; also for use in the medical pro- 

 fession for those engaged in research work, such as the comparison 

 and identification of bacteria and disease germs of every kind. 

 Hence the name " Comparascope," which has been given to the 

 invention. 



It consists of a vertical pillar fixed in a heavy case. To this 

 pillar is clamped at any required height a horizontal bar, which 

 carries at one end an objective, and at the other a mirror capable 

 of universal motions, whilst between the two there is a stage or 

 slide-clip, which traverses the bar by a rack-and-pinion movement 

 for focussing purposes, as the position of the objective is required 

 to be a fixture. 



On the nose-piece of the Microscope is screwed a fitting con- 

 sisting of a tube an inch long, with a hole in the middle of one 

 side. Inside this aperture is fixed a reflector of tinted glass, 

 worked to a perfect plane on its upper surface. It is placed at an 

 angle of 45° to the axis of the tube, beyond which it does not 

 extend, in order to allow free passage for the light from the primary 

 objective. 



A prism might be employed, but a reflector is more simple — in 

 fact the inventors in their early experiments used a Becks' vertical 

 reflector, with a prism turned to project the light upwards instead 

 of downwards, and they found the result was quite satisfactory. 



For use with high powers and wide-angled lenses a condenser 

 will necessarily have to be employed to illuminate the secondary 

 objeetive, and this is best effected by attaching a condensing system 

 to the movable stage, instead of giving it independent movement 

 on the same bar. 



In use the instrument is very simple, and there is no difficulty 

 in getting the fields equally illuminated, and if the lenses are 

 duplicates, the definition and magnification should be the same. 



