294 THE AMERICAN MONTHLY [Oct 



Universal Sizes. 

 Annual of Microscopy, London, Eng. 



In the year 1882 the Royal Microscopical Society ad- 

 vised that standard sizes for the diameters of eye-pieces 

 should be fixed, and those recommended were : — For large 

 microscopes 135" diameter, and for small instruments 

 .92" diameter. The latter has become practically univer- 

 sal, and is now used by nearly all the Continental and by 

 many British manufactures in students' microscopes. The 

 larger size never really became a standard one, and makers 

 have created sizes exclusively their own, without, from a 

 microscopist's point of view, a good and sufficient reason. 



It may be that they have felt that trade would be re- 

 tained in their own hands if they used exclusive sizes, 

 but the day for this has gone by, and the exigencies of 

 the microscopist must have precedence over the commer- 

 cial rapacity of the microscope maker. It has, in fact, in 

 recent years, been surprising that no co-operation has 

 taken place so as to bring this state of things to an end. 



We have hitherto regarded the Continental makers as 

 beyond the pale of conversion to any standard system, 

 and many people rubbed their eyes when it was announced 

 at a recent meeting of the Royal Microscopical Society, 

 that Reichert had supplied the universal size of substage 

 fitting to a new model of microscope that was exhibited. 

 Not many days after this it was hinted that the sub-com- 

 mittee of the society had under consideration the stand- 

 ardization of the substage and of the internal diameter 

 of the draw-tubes of the microscope, and at their meet- 

 ing on December 20th, the following resolutions were 

 adopted by the Council : — 



1. That the standards adopted by the Council in 1882 

 be withdrawn. 



2. That the standard size for the inside diameter of 

 the substage fitting be 1-527 inches = 38-786 mm. 



