280 the president's address. 



assure you that the selection of something suitable is not easy ; 

 and here, again, I am bound to admit that I have left the 

 customary paths, of which I hope you will approve when you 

 hear my reasons for so doing. You all know that it has usually 

 been the habit of the President to take for his subject the par- 

 ticular one with which he is most familiar j but I think you will 

 agree with me that, as a general rule, doing this has made a 

 rather dull evening for a great many of those present, simply 

 from the fact that only a limited number can take a genuine 

 interest in the special subject selected. T think special subjects 

 require special lectures, and then those not interested in the 

 particular line of research can silently steal out of the door — as 

 I see them gracefully doing sometimes — and catch early trains 

 home or seek more congenial environment. 



It is not easy to ascertain who first designed the short-tube 

 microscope, with its correspondingly corrected objectives, although 

 I believe it was Oberhaeuser, in France. Personally, my first 

 introduction was somewhere in the very early 'seventies ; but, of 

 course, on the Continent it Avas in existence long before this, and 

 I have a copy of a picture of one made in 1857. 



When first introduced into England, the short-tube stand and 

 its objectives were not well received by the majority of micro- 

 scopists. This arose from the fact that it was an unwritten 

 law — like that of the Medes and Persians, which altereth not — 

 that all, or very nearly all, the magnification of the object should 

 be performed by the objective, and as little as possible by the 

 ocular. Well can I recollect, several years ago, a learned man 

 writing to me concerning the construction of a certain piece of 

 experimental apparatus, to the effect that it was much the same 

 as if you " used the eye-piece to contribute anything more than 

 the smallest increment in the final magnification of the object 

 with the microscope," and was consequently not of good 

 design. 



Every one in this room knows from experience, that if the tube 



