52 the president's address. 



of an early collodion photo-micrograph of the " Proboscis of 

 the Blow-fly " is to be found on Plate VII. of Vol. I. of the 

 Microscopical Journal (as the Royal Microscojrical Journal was 

 then called). This was in the year 1853, and, all things being 

 considered, it was an exceedingly creditable performance, and 

 Mr. J. Delves deserved high commendation for his courage in 

 making the attempt in question. Some years passed before 

 very much work was done, or any real improvement made, 

 although there were several attempts, — the difference between 

 the chemical and visual foci of the objectives being so trouble- 

 some on the one hand, while, on the other, their manufacture 

 and computation were so poor, even in the preferred colour 

 for which they were corrected, that, given the overcoming of 

 the focus trouble, the actual image produced on the plate left 

 very much to be desired. This was due to so much outstanding 

 aberration of all kinds, which caused a fogging of the final picture, 

 and one peculiarity was that this fogginess seemed so much more 

 in evidence in the print than when viewing the object by the eye 

 through the same objective. When, however, the genius of Pro- 

 fessor Abbe led him to introduce his apochromatic objective, a 

 system so perfected as to bring three colours to actually the same 

 focus, photo-micrography started off with leaps and bounds. The 

 immediate introduction of the semi-apochromatic, with its very 

 perfect image in the preferred colour for which it was corrected 

 and the discovery of the orthochromatic plate, gave still further 

 impetus to the microscopist who desired to photograph his speci- 

 mens. Several workers now began to make sturdy attempts. 

 Those who succeeded in obtaining really satisfactory photographs 

 made public the results of their labours, and books commenced to 

 appear upon the subject to help those who desired to join their 

 ranks. Perhaps one of the very earliest written was that by a 

 Past President of this Club, Mr. T. Charters White. It was an 

 excellent little book, but it only dealt with low-power work. I 

 well remember having once spoken to Mr. Charters White upon 



