1900] MICKOSCOPICAL JOURNAL. 295 



3. That the gauges for standardizing eyepieces be the 

 internal diameters of the draw-tubes ; the tightness of the 

 fit being left to the discretion of the manufacturers. 



4. That the following four sizes of the internal diam- 

 eters of the draw-tubes be adopted : 



R. M. S. No. 1 .9173 inch r^ 23-300 mm. 

 R. M. S. No. 2 1-04 inches = 26*416 mm. 

 R. M. S. No. 3 1-27 inches = 32-258 mm. 

 R. M. S. No. 4 1-41 inches = 35-814 mm. 



5. That a set of plug and ring gauges of all the above 

 sizes be kept in the Society's rooms, and that the public 

 on payment of a small fee be allowed to inspect them. 



6. That the Society acknowledges with thanks the as- 

 sistance received from many firms in reply to circulars. 



NOTES. 



1. The substage guage adopted is that which has been 

 used by the English trade for many years past, the vari- 

 ation amongst different makers being not more than a 

 few thousandths of an inch. 



2. R. M. S. No. 1 is the Continental gauge. 



3. R. M. S. No. 2 is the mean of the sizes used by 

 the English trade for students' and small microscopes. 



4. R. M. r. No. 3 is the mean of the sizes used for 

 medium-sized binoculars and others of a similar class. 



.5. R. M.S.No. 4 is the maximum size for long binoculars. 



6. In all probability the eyepiece cap, and apparatus 

 to be used above the eyepiece, will be standardized in a 

 few weeks. 



Tlie above requires practically no comment. That the 

 Royal Microscopical Society is the fit and proper body to 

 arrange such a matter is beyond dispute, and if the in- 

 fluence of its Council and members is not sufficient to 

 cause the matter to be taken up by manufacturers, then 

 nothing further can be done, but we venture to hope that 



the labors of the sub-committee will not be fruitless. An. 



of Microscopy. 



