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NOTICES OF BOOKS. 



Principles of Microscopy. By Sir A. E. Wright, M.D. 

 (Dublin), E.R.S.-, Hon. D.Sc. (Dublin), Hon. F.R.C.S.I. 

 10 x 6| in. 250 pages, with many illustrations. London: 

 Archibald Constable and Co., Ltd. Price 21s. net. 



This most valuable work is a treatise upon the microscope, 

 both simple and compound, considered from a purely optical 

 standpoint. The tyro might well, after glancing casually 

 through its pages, replace it upon the bookshelf under the impres- 

 sion that it was something beyond his possibilities ; but let him 

 commence at the beginning and conscientiously follow the 

 author's demonstrations, and he will be surprised at the vast 

 amount of valuable information which he can thus acquire with 

 the expenditure of a very moderate amount of intellectual effort. 

 The subject is treated in a thorough and systematic manner, and 

 is neatly divided and subdivided to facilitate reference. There 

 is an air of business-like earnestness about the whole work which 

 cannot fail to produce a favourable impression upon those for 

 whom it is intended — those, in the author's own words, who 

 desire to master the scientific principles of microscopy. 



A noteworthy feature of this work is the insertion of a large 

 number of experiments, most of them capable of being performed 

 with nothing more than the most homely apparatus ; and every 

 experiment has for its purpose the demonstration and forcing 

 home of some point which might otherwise be overlooked or 

 forgotten. A simple but very effective one, for example, is that 

 shown on Plate II. e, where a pattern of white discs upon a 

 black ground is seen as black discs upon a white ground by 

 bringing the eye beyond its range of accommodation. (This is 

 reversed in the description of the experiment — a matter, however, 

 of little consequence.) 



In connection with these experiments there is affixed to the 

 cover of the book a little pocket which contains a neatly mounted 

 grating of 400 lines to the inch, w r hich enables the student, 

 without further outlay, to personally verify many of the facts 

 concerning diffraction, a subject which has been brought so promi- 

 nently before microscopists by the theories of Professor Abbe. 



The work includes eighteen plates, mostly diagrammatic, and 



