ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 10.~> 



Edee, J. M. — Jabrbuch fur Photographie und Reproduktionstechnik. 



[The " Separat-abdruk " from the above summarizes with its usual com- 

 pleteness the most important progress made during the year.] 



Halle : Wilhelm Kuapp. 



Linder, P. — Mikro-photographische Aufnahmen von lebenden Objekten in der 

 Rune und in der Bewegung. Muschau, 1910, p. 787. 



(5) Microscopical Optics and Manipulation. 



Interference Phenomena in Polarized Light.* -- These three 

 volumes, l>y the late Hans Hauswaldt. together form the most com- 

 plete black-and-white photographic record of polarization phenomena 

 that has ever been produced, and which it is very unlikely will ever be 

 surpassed. The work has been done with characteristic German 

 thoroughness. Neither brains, time, nor money have been spared. 

 This statement will be understood when it is remembered that the 

 various crystal sections used were prepared by Steeg and Reuter, the 

 apparatus employed was made by Carl Zeiss, and the description of the 

 same was written by Siedentopf, of ultra-microscope fame. 



The first volume consists of some thirty-three full-sized autotypes 

 showing the stanroscopie figures produced by plates of various thick- 

 nesses, and cut at different obliquities to the axis, in white ami sodium 

 light, of such typical uniaxial crystals as calcspar, nitrate of soda, 

 apatite, zircon, quartz (including amethyst), and such biaxial crystals as 

 arragonite, mica, gypsum, topaz, and sugar. 



The illustration given shows one of these plates. Fig. 1, pi. III., is 

 the figure giveu by a plate of apatite, cut normal to the axis of the crystal, 

 in sodium light and between crossed nicols ; whilst tig. 2, pi. III., shows 

 the same plate combined with a quarter-wave mica, to show the test for 

 negative crystals. Figs. 3 and 4, pi. III., show similarly the figures giveu 

 by a plate of zircon — a positive crystal. 



The second volume, containing eighty plates, is a very interesting 

 one. It gives, in the first place, the different figures obtained in con- 

 vergent sodium light — the X.A.'s employed being O'GSG, 1"168, and 

 1'70 — in such crystals as calcspar, topaz, gypsum, etc. These figures 

 are followed by others showing the effect of using practically mono- 

 chromatic lights of different wave-lengths in calcspar and brookite. 

 The mica combinations of Rensch and Xorrenberg, the spectrum 

 analysis of the colours produced by double refraction, and the figures 

 produced by various shapes of glass, stressed in different ways, are finally 

 dealt with. 



The third volume, of seventy-two plates, deals largely with the 

 phenomena produced by circularly polarized light, twin crystals, etc. 



Enough has been said to indicate the complete nature of the work 

 done by Hauswaldt. This, as will be seen, is not so remarkable for the 

 originality of the problem, attacked as it is for the thoroughness with 

 which work so often attempted by others has been done. Indeed, until 

 colour-photography becomes practical for this class of work, it would be 

 labour in vain for anyone to attempt to rival the work of Hauswaldt. 



* Interferenz-Erscheinungen an doppeltbrechenden Krystallplatten im kon- 

 vergenten polarisirten Licht. By Dr. Hans Hauswaldt. Magdeburg, 1902 (33 pis.) ; 

 Op. cit., 1904 (66 pis.) ; Op. cit., 1907 (80 pis.). 



