THE president's ADDRESS. 185 



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 differing 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 

 correction collar, it is necessary that such an ideal instrument 

 as I am projecting should be fitted with a draw-tube capable of 

 considerable extension by rack and pinion. The substage also 

 should, I think, receive more attention than is now generally 

 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 re- 

 membered that the substage of a full-sized stand has to support 

 and focus, without tremor or oscillation, a considerable weight 

 of apparatus. My own substage, for example, fitted with an 

 achromatic condenser, which, by the way, is always in position, 

 weighs not less than 1 lb. 6 oz. Unless, therefore, the mechanism 

 which sustains and moves this load be substantially and accu- 

 rately constructed, it is obvious that the strain will inevitably 

 disarrange the necessarily delicate adjustments of the instrument. 

 In my opinion, which has not been formed without con- 

 sultation with experienced workers in this metal, it is in the 

 construction of the substage and the apparatus supported thereby, 

 as well as in that of the double or triple nosepiece, that 

 aluminium, as a much lighter substitute for brass, seems to 

 promise to be useful. That substages, and indeed complete 

 microscopes of great perfection, can be made of this metal, or 

 rather of one of its alloys, has been abundantly shown by 

 Messrs. Swift at one of our recent meetings ; and although 

 opinions may differ as to the advisability of constructing any 

 but a portable stand, like the one shown by Mr. Swift, 

 exclusively of aluminium, it will, I think, hardly be contended 

 that anything but advantage could result from the use of this 



* The instrument I refer to is Powell & Lealand's No. 1 Stand. This 

 is the type to which all recent improvements in English stands have 

 approximated, as far as I am aware. 



