204 THE AMERICAN MONTHLY [Juae 



ing more than coarse and fine movements to the body, 

 simple square stage and sliding bar ; but they possessed 

 the very obvious advantage that they were capable of be- 

 ing built up into instruments of great completeness, ac- 

 cording to the wish or means of the purchaser, and hav- 

 ing been originally designed accordingly, they were not 

 overbalanced by subsequent additions. Thus a mechani- 

 cal stage, with universal movements, a rack-and-pinion 

 focussing substage, with centering and rotating adjust- 

 ments, could be adapted, binocular bodies could be added 

 if desired, and all other apparatus required by the most 

 accomplished microscopist. I believe that I am not 

 awarding praise unfairly when I say that the firm of Ross 

 & Co. were the first to introduce this excellent plan, which 

 was subsequently adopted for a brief season by most of 

 the other London opticians. I purposely bring into 

 prominence what is now — unfortunately, as I think — ^a 

 matter of ancient history, because lam confident that the 

 present rage for a so-called complete microscope of the 

 small Continental pattern will eventually pass away. I 

 believe, further, that at no distant date the instrument for 

 the study, as distinguished from the laboratory, will be a 

 solidly built English stand of full dimensions, mounted 

 on a heavy tripod base, and dilfering little in general 

 form from that type which many of us in this Club know 

 so well how to appreciate. To meet the present fashion 

 of constructing objectives without correcting collar, it is 

 necessary that such an ideal instrument as I am project- 

 ing should be fitted with a draw-tube capable of consid- 

 erable extension by rack and pinion. The substage also 

 should, I think, receive more attention than is now gen- 

 erally devoted to this important part of the stand. It 

 should be much more substantially constructed, and its 

 movements should be more delicate and steady than is the 

 case at present with any but the most costly instruments. 

 It must be remembered that the substage of a full-sized 



