80 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



with blackened inner surfaces, the mirror being set obliquely in one of 

 its sides. The box has a lid for the adjustment of the image, and later- 

 ally a catch for the insertion of the plate. The plate must be laid on a 

 frame of corresponding size whose under surface can be raised or lowered 

 to the height required for the image. In arranging the adjustment a 

 piece of white paper the size of the plate is first laid in the frame. The 

 insertion of the actual plate must naturally be performed in complete 



Fig. 12. 



darkness. The light-exposure depends on the light-strength and magni- 

 fication, and varies from fractions of a second up to two seconds. The 

 author finds that with this apparatus very useful photomicrographs can 

 be taken. 



(5) Microscopical Optics land Manipulation. 



Exercises in Scientific Microscopy.*— Part 2 of this series has now 

 been published, and has been compiled by H. Ambronn and H. Sieden- 

 topf . It is exclusively devoted to Abbe's theory of the Microscopic 

 image. All the usual grating experiments with their effects on pleuro- 

 sigma angulation are collected and described in such a form that they 

 may be easily followed by the student. The experiments are copiously 

 and clearly illustrated. 



Ainslie, M. A. — Microscopical Measurement of Magnifying Power: Measurement 

 of Numerical Aperture. 



[Two very practical and interesting letters on the above subjects.] 



English Mechanic, xcviii. (1913) pp. 60 and 111. 

 Orueta, Domingo de — La luz ultra-violeta y sus aplicaciones en microscopia 

 con un resumen de los trabajos hechos en el laboratcrio del autor durante el 

 ano 1911 y primer semestre de 1912. 



[The author gives a very complete account of ultra-microscopical methods 

 and of the results obtained.] 



Reprinted from the Bevista de la real Academia de ciencias 

 exactas, fisicas y naturales de Madrid (1913) 92 pp. (14 pis.). 



* Ubung. zur Wiss. Mikrosk. Leipzig : S. Hirzel, Heft 2, 28 pp. (39 figs.) 



