.52 



On a Quick-acting Adapter for Microscotical Objectives. 



By E. M. Nelson. 

 {Read September 2, 1882.) 



It is obvious to everyone that the present method of screwing 

 or unscrewing objectives is a very tedious one. 



To remove this objection I have thought of several devices 

 which I was obliged to abandon because they would not be inter- 

 changeable with existing arrangements. 



The plan which I now bring before you has no such objection. 

 It was suggested to me by the method employed by the French in 

 closing the breech of their breech -loading ordnance. It consists in 

 simply cutting away three portions of the Society's screw in the 

 nose piece and three similar portions in the objective. To fix on 

 an objective it is merely necessary to push it home in the nose- 

 piece and give it one- sixth of a turn to the right ; a similar turn to 

 the left will as readily release it. 



In order that these altered nose-pieces and objectives may be 

 made interchangeable with one another, all that is required is that 

 similar portions of the screws shall be cut away. 



To insure this I have had a template made by Messrs. Powell 

 and Lealand, which I have much pleasure in presenting to the 

 Club. 



A mark should be made on the objective to shew the proper 

 position for its insertion in the nose-piece. 



I propose that this mark be made on the front of the nose-piece, 

 and a similar one on that side of the objective which is to be placed 

 in a line with the front of the nose-piece at the time it is in- 

 serted. 



ADVANTAGES. 



This arrangement appears to me to possess the following ad- 

 vantages : — 



The rapidity with which objectives may be changed. 



It can be applied without interfering with existing arrangements. 



It can be made interchangeable. 



