OF ARTS AND SCIENCES. 147 



this country has furnished to the common stock, — such as the 'Odon- 

 tography ' of Professor Owen, the ' Researches into the Structure of 

 Shell ' carried out by Mr. Bowei'bank and myself, the ' Physiological 

 Anatomy ' of Messrs. Todd and Bowman, the first volume of the ' His- 

 tological Catalogue ' by Professor Quekett, and the ' British Desmideae ' 

 of Mr. Ralfs, — we find sure reason to conclude that these researches 

 must have been made with the instrumentality of lenses, which would 

 in the present day be regarded as of very limited capacity. — I hope 

 that, in these remarks, I shall not be understood as in any way desirous 

 to damp the zeal of those who are applying themselves to the perfec- 

 tionizing of achromatic objectives. I regard it as a fortunate thing for 

 the progress of science, that there are individuals whose tastes lead 

 them to the adoption of this pursuit ; who stimulate our instrument- 

 makers to go on from one range to another, until they have conquered 

 the diflaculties which previously bafiied them ; and then apply them- 

 selves to find out some new tests, which shall offer a fresh difficulty to 

 be overcome. But it is not the only, nor can I regard it as the chief 

 work of the microscope, to resolve the markings upon the Diatomaceae, 

 or tests of the like difficulty ; and although I should consider this as the 

 highest object of ambition to our makers, if the performances of such 

 lenses with test-objects were any fair measure of their general utility, 

 yet as I think that I have demonstrated that the very conditions of 

 their construction render them inferior in this respect for the purposes 

 of ordinary microscopic research, I would much rather hold out the 

 reward of high appreciation {ive have no other to give) to him who 

 should produce the best worMng microscope, adapted to all ordinary 

 requirements, at the lowest cost." ' 



" Notwithstanding the approval of those, as Dr. Carpenter says, 

 ' who have most successfully employed the microscope in physiological 

 investigations,' I do not hesitate for a moment to declare, that nothing 

 could be more pernicious to the best interests of science than these re- 

 marks. It is unfortunate that such mistaken views should be displayed 

 on this subject, where so great confidence has been placed, — by one, too, 

 whose elementary works on physiology have raised the belief, among 

 many, that he is perfectly conversant with those very tissues which re- 

 quire the nicest and most rigid microscopical investigation. 



" The illustrations which I have given, of the great value of highly 

 corrected lenses in the study of minute structures, are sufficient, I 



