134 



v.— SOME SUGGESTION'S EEGAEDING 

 THE MECHANICAL DESIGN OF MICEOSCOPES. 



By Captain Frank Oppenheimer, I. M.S., M.B., 

 Ch.B., F.E.M.S. 



(Read Apr-il 20, 1921.) 



The meclianical design of the modern microscope has of late 

 been receiving increasing attention, and formed an important 

 subject for discussion at the recent Symposium held by the allied 

 scientific Societies, 



On this occasion the need for improved design was emphasized, 

 but very few definite suggestions as to the line such improvements 

 should follow were brought forward, except that the optical- bench 

 principle should be more fully applied to the higher types of 

 instrument. As one who uses the highest type of microscope 

 for critical work, and is at the same time a constant worker in 

 medical laboratories, I venture to put forward a few concrete sug- 

 gestions for alterations or improvements, some of which are intended 

 for incorporation in the highest type of instrument, and others for 

 the ordinary laboratory or standard microscope, and some of whicli 

 might be applicable to both types. It is only right to state that I 

 have not had the opportunity of having these ideas incorporated in 

 an experimental instrument owing to the prohibitive cost. 



First, with regard to concentric, rotating, and centreing motions 

 to the stage. 



As usually constructed, this is a most expensive item in 

 microscope construction, owing to the fine machining and fitting 

 required for the two concentric rings which form the bearing of 

 the rotary mechanism. It is, moreover, usually impossible to 

 compensate for wear, the consequence being that the stage drops 

 slightly when the microscope is brought to the horizontal position, 

 and a certain undesirable play is given to the upper stage as a 

 whole. 



In the design suggested the centreing and rotatory movements 

 are combined in a single simple fitting which is more or less 

 geometric, and which cannot possibly develop shake or play in any 

 direction. 



The bottom plate of the rotating stage A has attached to it 

 underneath a turned bronze ring B, in which is turned a channel of 



