862 SUMMARY OF CURRENT RESEARCHES RELATING TO 



W. T. Suffolk. May 1.1, The Structure of Mosses, by Dr. E. Braith- 

 waite. 



We are glad to find that this experiment is at last to be tried. 

 That it should be done has been for several years the strong wish of 

 many of the members. As, however, it was found that the suggestion 

 gave offence to leading officials of the Club, it was not further 

 pressed, in the hope that at some future time the force of events would 

 enable the question to be dealt with on its merits and apart from, any 

 personal predilections one way or the other. 



Hogg on the Microscope.* — A new (10th) edition of this book 

 (bearing the date of 1883) has just been issued. It is now so well 

 known from the numerous editions through which it has passed, 

 extending over a period of nearly thirty years, that it is superfluous 

 to describe its general plan. The new edition bears the marks of 

 extensive revision, especially in the parts relating to the Microscope 

 proper, which have in fact been nearly rewritten. 



It is almost unnecessary to say that the book contains that without 

 which no treatise on the Microscope is now complete, viz., an explana- 

 tion of the Abbe theory of microscopical vision, and of the pons 

 asinorum of the old school of microscopy — the aperture of objectives. 

 Pages 69 to 80 are devoted to the most succinct and at the same time 

 complete statement of the latter subject that has yet been printed. A 

 similarly succinct statement of the principles on which homogeneous- 

 immersion is based is given in pages 82 to 86. A chapter has been 

 added on the application of the Microscope to mineralogy and spectro- 

 scopic analysis and the examination of potable water. 



By a slip the preface omits to mention that more than fifty of the 

 new woodcuts were lent by the Council of this Society, having 

 originally appeared in this Journal. 



The author may be congratulated on the issue of the new edition 

 and on the fact that his book has so long maintained so large an 

 amount of popularity. 



Wright's Experimental Optics.f — This is also a book on which 

 the author may be very much congratulated, as in our view it is by far 

 the most useful work on its subject to which the general body of 

 microscopists can refer. It is written throughout from an experimental 

 point of view, and the author's endeavour (to use his own words) has 

 been " to place clearly before the mind of the reader, through something 

 like a complete course of actual experiments, the physical realities 

 which underlie the phenomena of Light and Colour. As helps, there 

 are solely employed simple mechanical analogies, and a few diagrams, 

 explained in language which it is hoped may be found in reality 

 simple and clear though not intended to be childish or to debar any 

 private student from the healthful exercise of now and then consider- 

 ing what the writer means." We think that the author's explanations 



* Hogg, J., ' The Microscope : its History, Construction, and Application.' 

 New (10th) ed., xx. and 764 pp., 8 pis., and 356 figs. (Svo, Routledge, 1883). 



t Wright, L. , ' Light : a course of Experimental Optics, chiefly with the 

 Lantern.' xxiv. and 367 pp., 8 pis., and 190 figs. (Svo, Macmillan, 1882). 



