2162 Journal of Applied Microscopy 



A New Changing Nosepiece. 



So many different styles of nosepieces, objective changers, etc., have been 

 devised that it may appear superfluous to add another to the Hst. 



The nosepiece illustrated has, however, advantages which, I believe, are suf- 

 ficient to warrant its finding a place among practical laboratory appliances. 



For petrographic, metallographic and photographic work a readily change- 

 able nosepiece which will not interfere with the manipulation of the specimen 

 or the mechanical stage is desirable. 



This form of nosepiece has been produced in a number of varieties, with 

 portions of the thread cut away, in the form of a lathe chuck, with spring fork 

 to clutch a ring screwed to the objective, and the sliding wedge form objective 

 changer. 



In the first two forms the objective cannot be placed in position without 

 raising the body tube, except when changing low power objectives. In the third 

 form there is little security and the objectives are not liable to center. In the 

 last the only real objections are the expensive construction, the weight, and the 

 need of a special box to contain the objectives fitted with the slide pieces. 



The nosepiece illustrated consists of a circular 

 case, one end provided with the society screw thread 

 for attaching to a microscope (a clamping ring is fitted 

 to the thread so that the nosepiece may be brought to 

 the proper position), and at the lower end the case is 

 cut away at one side to permit the passage of the rings 

 carrying objectives. Thege rings are designed in a 



^. . ^, . manner not only to admit of ease in placing them in 



Changing Nosepiece. _ , •' ... 



position, but also to ensure centering of objectives. 



The lower surface is flat, whereby the rings can be easily placed or displaced. 



The upper portion is conical on the outside, and fitting, as it does, the inside 



adjustable bearing of the nosepiece, the ring is brought to a fixed center. 



The adjustable bearing is inside the case and is forced down upon the ring 

 by means of a stiff spring. The raising of this bearing is accomplished by a 

 lever, in an inclined slot, ending in a knob on the outside of the case ; this im- 

 parts a rotary motion to the adjustable piece and is superior to a straight up and 

 down movement. 



All parts of the nosepiece must be carefully made and adjusted, and it is pre- 

 sumed that the objectives have been centered and made parfocal with each 

 other; otherwise good results cannot be expected. 



The objectives can be placed in the optical axis by pressing the small lever 

 to one side and sliding the objective, with ring attached, into the clutch; upon 

 releasing the lever the objective is centered by the conical objective part being 

 forced into the conical rim of the nosepiece by the spring of the inside bearing. 



Objectives made parfocal will remain so when used on this nosepiece, and 

 the objectives can be changed without raising the body. 



The nosepiece is light and small, and not at all in the way when manipulat- 

 ing the specimen. The rings are so small that objectives can be kept in the 

 boxes regularly supplied with them. W. L. Patterson. 



