204 Transactions of the Socidij. 



I recommentleJ this plan, who as yet has adopted it ; bnt be is so 

 far satisfied with the results that he tells me he shall continue to 

 do so. Hence I hope that an instrument which allows objectives to 

 be thus tested easily, and with ample illumination, may produce 

 some improvement in this respect. Micro-photographs of lines of 

 print are excellent tests for this purpose. 



Finally, I wish to thank those who have aided me in my 

 experiments. To the Kev. P. K. Sleeman, Mr. Adolf Schulze, 

 and several others who do not wish their names mentioned, I am 

 indebted for trial of previous lantern Microscopes. Mr. T. Sebastian 

 }-5azley, Mr. T. Curties, Mr. Washington Teasdale, and Mr. Crisp, 

 have kindly furnished me with objectives, the two former with 

 large and valuable collections. To Dr. Carpenter I have been 

 indebted for both objectives, for valuable advice as to an assortment 

 of test-objects and what ought to be made visible in them, and for 

 some of his own slides for my earliest experiments. ]3ut to no one 

 are my obhgations greater than to Mr. A. Topping, who has 

 given much personal eflbrt to supply such slides as were deemed 

 desirable, and who in particular, when he knew that I had in vain 

 endeavoured for months to procure the section of a fly's eye 

 sufficiently minute in detail, made it his special study to prepare 

 one for me in time for the meeting on November r2th. It is not 

 that such slides as some he thus prepared are specially easy to 

 show ; in some respects the contrary is the case, and a coarser 

 slide would be easier ; but the labour in preserving the utmost 

 detail has been considerable. I am glad to report that Mr. Topping 

 found in such a task something of the same personal fascination I 

 found in my own ; since others may find similar advantage in pro- 

 curing, not only from his hands, but doubtless from others also, 

 similar high-class work for special purposes.* I must not forget to 

 add that from Dr. Maddox and Mr. Crisp I also received timely 

 bibhographical help regarding certain points — especially the con- 

 cave amplifier (which is by the way a very ancient lantern 

 expedient) — concerning which I particularly wished to know what 

 had been done by others. 



I hope ere long to have an opportunity of testing what this 

 lantern ]\Iicroscope will perform with the electric arc. The small- 

 ness of the radiant, as well as its greater brilliancy, will give this 

 a great advantage with high powers; and if any of the lamps 

 obtainable will keep steadily in focus, I have every reason to 

 believe that almost anything can be shown up to 5000 diameters. 



* A blow-fly's proboscis thus prepared for me, was pronounced by one of the 

 most able photo-micrographers in England, to be mncli the best he had tried, out 

 of dozens, for photographic purposes ; and exquisite photographs were sent nie of 

 it upon a very large scale. 



