ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



635 



poised. The form of the glass prism and the autocollimation of the 

 rays are shown in fig, 160. 



Modification of Rousselet'g Compressor. — At the meeting of the 

 Society held on June 20th, Mr. G. H. J. Rogers, of Maidstone, exhibited 

 a modification of the Eousselet compressor, the chief feature of which 



Fig. 164. 



consisted in the employment of two indiarubber bands in suitable 

 grooves to keep the glass in position, instead of having it cemented. It 

 was claimed that this saved trouble and time in the event of the glass 

 being broken. Fig. 163 shows the instrument open ; A A are the india- 

 rubber bands; BB the grooves to receive the bands; in fig. 164 the 

 instrument is shown closed. 



Marktannee-Turneretscher, G.,F.K.M.S. — Bemerkungen fiber Lichtquellen 

 fur Projectionsapparate und mikrophotographische Zwecke. (Observations on 

 Light Sources for Projection Apparatus and Photomicrographic Purposes.) 



[The author reviews the various kinds of available artificial light and especially 

 Liesegang's ether jet.] 



Laterna Magica, xvi. (1900) April, pp. 17-26 (1 fig.). 



(4) Photomicrography. 



Oheyney, J. S. — Photomicrography. 



[A practical treatment of the subject.] Micro. Bull, June 1900, pp. 17-9. 



M arkt ann er- Turn ere t scher, G. — Fortschritte auf dem Gebiete der Mikro- 

 photographie und des Frojectionswesens. (Progress in the Department of Photo- 

 micrography and Projection.) 



[A deacriptive catalogue of the chief novelties pertaining to the subject collected 

 from international scientific journals for past year.] 



J. M. Eder's Jahrb.f. Plwtog. it. Beproductionstechnik f. 1900. 

 (Also as a separate pamphlet, 18 pp. and 8 figs.) 



(5) Microscopical Optics and Manipulation. 



Abbe's Refractometer. — This instrument, first designed by Prof. 

 Abbe in 1874, has lately undergone some improvements by Dr. Pulfrich.* 

 The optical improvement consists in removing the polish from the plane 

 "of the under part of the double prism and replacing it by a frosted 

 surface. It is found that the effect is to obliterate the troublesome 

 images of adjacent objects which were apt to obtrude themselves into the 

 field of view and distract the observer. The Zeiss firm recommend the 



* See Zeitschr. f. Instrumentenkunde, 1898, pp. 107-12 (5 figs) 



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