184 Transactions of the Society. 



amongst microscopists, and now it remains only to the sons of the 

 late Mr. Hugh Powell The distinguished man whose name I have 

 just mentioned was amongst the first of the Fellows of this Society, 

 and long before the year 1840, he had become celebrated for his 

 microscope-stands and lenses. His name will always be remembered 

 as that of a designer and maker of first-class high-power objectives, 

 and as a conscientious maker of the ordinary powers. The follow- 

 ing obituary notice has been already published, and it expresses the 

 merits of Mr. Powell : — 



" In 1834 he was awarded a silver medal by the Society of Arts 

 ' for a stage for a Microscope.' In 1840 he succeeded in making 

 an achromatic object-glass of 1/16 in. focal length, which the late 

 Professor Quekett, in his treatise on the Microscope, stated was ' the 

 first that had been seen in this country ' ; and in 1841 the Society 

 of Arts awarded him a silver medal 'for his mode of mounting 

 the body of a Microscope.' Mr. Powell was the first optician in 

 England to construct object-glasses on Amici's ' immersion ' system. 

 A 1/25 in. was made by Mr. Powell in 1860, a 1/50 in. was per- 

 fected in 1864, and a 1/80 in. in 1872. The more recently de- 

 veloped formula of the ' homogeneous immersion ' system was the 

 subject of special attention on the part of Mr. Powell and his 

 brother-in-law and partner, Mr. Lealand, but failing health com- 

 pelled him to rely upon the eiSbrts of his son, by whom object- 

 glasses on this formula having the highest apertures on record 

 have been constructed. Mr. Powell was among the earliest on the 

 roll of Fellows of the Society at its foundation in 1840." 



Microscopical science has also to deplore the death of a very 

 able and most distinguished practical optician in the United 

 States. Mr. Eobert B. ToUes has left a name in America and 

 Europe which will always be mentioned with respect. He was a 

 skilled objective-maker of the first class, and like most men of his 

 mental and artistic calibre was a quiet and unassuming gentleman. 

 ToUes was always ready to avail himself of discoveries and seized 

 at once upon the value of the lenses with large numerical apertures, 

 and he also speedily availed himself of the improvements of the 

 homogeneous-immersion principle. He was not, as one of his 

 friendly biographers states, entitled to the credit of showing the 

 practicability of this system. It was Amici, Stephenson, and Abbe, 

 as I stated in my first Presidential Address, who established the 

 homogeneous-immersion system. Tolles, however, developed the 

 apertures of high-power objectives and produced admirable results, 

 being the first to manufacture combinations of lenses of high 

 amplification and suited to the immersion system in America. 



The last obituary notice relates to Henry Dallmeyer, who 

 was so well known in the sister sciences of astronomical and 

 photographic optics. Mr. Dallmeyer left Germany in 1849 



