328 Ee-cnt Microscopic Literature. 



KECEXT MICROSCOPIC LITERATURE.* 



Ix the last annual address of the President of the Microscopi- 

 cal Society of London, Mr. Brooke stated, " that no for€ 

 microscope that was exhibited (at the International Exhibition) 

 was at all comparable, either in the convenience of its mechani- 

 cal or the perfection of its optical arrangements, with the instru- 

 ments of our best makers/' This has been the case pretty 

 uniformly since the application of the achromatic principle to 

 the construction of the microscope ; but it is only recently that 

 our opticians hare successfully competed with the French in the 

 useful task of giving a serviceable, though second or third-rate 

 instrument, at a low price. At present, it would appear that if 

 optical and mechanical excellence, both carried to the highest 

 degree of perfection, be sought for, they will be found in the 

 workshops of our own great makers; while no foreign artist whose 

 productions we have seen appears to give so much for a little 1 

 money as can be obtained in the educational and student's 

 microscopes of Smith and Beck, Pillischer, Baker, Parkes, and 

 many others whose names are familiar to all who have paid 

 attention to this branch of manufacturing industry and scien- 

 tific skill. Almost the only feature in foreign instruments 

 which Mr. Brooke commends to the attention of English 

 is the correction of certain objectives for immersion in water, a 

 form of construction in which M. ilartnack, who exhibited in 

 the French Dep excels. Mr. Brooke tints 



upon these : — "A plate of water should intervene 



the objective and the c -glass of the object. 



From the increj ility of transmission of the oblique 



plate of water, the quantity of light uh 

 comdition of illumination is obviously increas 

 i!c With a ,\tii objective of moderate angul 



, which is corrected f"i- immersion in water, I bi 

 I think, in some i: obtained better definition than 



by any oth< i aarks it will be 



that the film of water makes a small angled glass work like 

 a Lai , and although there may be some pare occasions 



in which the plai preference, it cannot be bo gene- 



rally useful or advisable as that which our opticians have so 



ill (Mil. 



Mr. I as ] >r. I ' 



did long ago, on the question of[angular aperture, which, he 



* L'Eludiant M Par Arthur Chevallier. Paris: Delahaye. 



Preparing and Mounting Mi Objects. By Thomas Daries. llard- 



wicke. 



of Microscopical Science. No. sir. Churchill. 



