300 SUMMAKY OF CURRENT RESEARCHES RELATING TO 



G-reenough Binocular Microscope.* — F. Emich describes a method 

 by which he has succeeded in increasing the magnifying power of 

 binocular Microscopes of the Greenough type without diminishing their 

 advantages. It is well known that without the use of very strong 

 oculars it is difficult to get a magnification with this instrument higher 

 than 50 to 60 diam. The author, however, has designed an objective 

 in a special mount large enough to fit over the noses of the two tubes. 

 Although there is a certain weakening of illumination, the efficiency 

 of the instrument is practically unimpaired, and very satisfactory results 

 have been secured. The firm of C. Reichert have constructed the 

 special objectives for him with focal lengths of 12 and 8 mm. 



With ocular ii the magnifications respectively attained are 90 and 

 150 diam., and with ocular iv, 125 and 210 diam. With ocular v 

 magnifications of 190 and 320 diam. would be reached, but the author 

 has not, so far, had occasion to use them. The special objectives are 

 slid on in the usual way and can be conveniently exchanged. As an 

 example of his results, the author mentions his observations of Brownian 

 movement obtained in a damp chamber with a drop of hydrochloric acid 

 and piperidin. Illuminated by an arc-lamp and viewed through a dark- 

 ground condenser, the object forms a beautiful image. 



Luminescence Microscope : its Construction and its Applica- 

 tions, f — In this monograph of upwards of fifty pages H. Lehmann 

 deals very fully with the Luminescence Microscope. The author divides 

 his article into six chapters, and we reproduce his table of contents. 



I. The Principle of the Luminescence Microscope. — Luminescence. 

 Luminescence analysis. The U-V filter. The U-V filter-lamp. The 

 Luminescence Microscope. (Pages 418-22.) 



II. The Development of the Luminescence Microscope: Historical. — 

 A Kohler's U-V Microscope : fluorescence observations with bright- and 

 dark-ground illumination. The author's experiments with U-V filter 

 and dark-ground illumination. Eeichert's fluorescence Microscope. 

 Principle of the new Luminescence Microscope and its advantages. 

 (Pages 422-27.) 



III. Theoretical. — On the image theories of self-luminous objects 

 and non-self-luminous objects. Lommel's law of emergent rays. 

 Review of refraction-polarization of luminescent light. Test of the law 

 of emergent rays by new modes of demonstration. New theory of 

 marine light. Discussion of the appearances in the luminescence Micro- 

 scope. (Pages 427-44.) 



IV. Experimental Arrangements for Visual Observation.— The light- 

 source. The illumination system. The U-V filter and the supplementary 

 filter. The euphos cover-glass. The Microscope. Arrangement for 

 illumination with visible light. Abbe's microspectral ocular. Engel- 

 mann's microspectral photometer. Observation through the analyser. 

 The phosphoroscope. (Pages 444-55.) 



V. Experimental Arrangements for Photography. — Photography on 



* Zeitschr. wiss. Mikrosk., xxx. (1914) pp. 487-9 (1 fig.). 

 t Zeitschr. wiss. Mikrosk., xxx. (1914) pp. 418-70 (1 pi.). 



