ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 517 



aplanatic combination at the point corresponding to the cardioid-cusp 

 are easily followed. 



For successful use of the apparatus, Microscope objective and con- 

 denser, must be accurately centred upon each other, and the strongest 

 available light-source (arc-light or sun-light) is required. For gas or 

 electric incandescent light the paraboloid condenser, with its simpler 

 management, will suffice. 



Drawing on a Transparent Drawing-surface.* — H. Tafner points 

 out that certain difficulties attend the use in strong light of such projec- 

 tion apparatus as that of Tandler and Edinger. The strong light throws 

 such intense shadows that it is not altogether easy to trace in the out- 

 lines, especially when there is much detail. The author suggests that 

 these' difficulties may be overcome by projecting, not on to an opaque 

 surface, but on to a transparent one. He finds that a successful method 

 is to draw by means of an engraver's needle on a gelatin film spread out 

 on a matt-glass sheet. Needles of varying degrees of coarseness may be 

 used to suit the work. By the help of graphite or powdered red chalk 

 the lines may be filled in. and the picture is like a photographic negative 

 ready for copying, and many copies may be struck off by a press. The 

 author describes the details of manipulation, and explains how certain 

 difficulties can be avoided. It is also possible to transfer the gelatin 

 film to a copper-plate. 



(4) Photomicrography. 



Davis, W. S. — Photomicrography with Simple Apparatus. 



Photo Era, 1908, p. 20. 



Gar jeanne, A. J. M. — A Home-made Photomicrographic Apparatus. 



The Photograph Monthly, xvi., p. 28. 

 M arkt anne r-T urn erets cher, G. — Wesentlichere Fortschritte auf dem 

 Gebiete der Mikrophotographie uud Projection. 



Jahrb. f. Photogr. u. Reproduckt. fur d. Jahr 1909. 



Published by J. M. Eder. 

 Milse, J. R. — A Special Form of Photographic Camera for recording the Read- 

 ings of the Scales of Scientific Instruments. 



Proc. Hoy. Soc. Edinburgh, xxix. (1908) pp. 176-81. 



Monpillard, M. — Nouveau dispositif pour la microphotographie instantanee 

 de M. Briandeau a Nantes. 



Bull. Soc. franc, de Photogr., xxv. p. 73. 



Reid, J. — Photography and the Microscope; more particularly a Method of 

 Calculating the correct Exposure. Photog. Journ., xlix. p. 33. 



(5) Microscopical Optics and Manipulation. 



Measurements in the Long-waved Spectrum. f — H. Paibens and 

 H. Hollnagel give the following summary as the result of their investi- 

 gations : 1. The wave-length and energy distribution of the ultra-rays 

 of rock-salt, sylvine, potassium bromide, and potassium iodide were 

 examined by means of a quartz interferometer. 2. It was found that 

 the ultra-rays of rock-salt, sylvine, and potassium bromide were com- 

 posed of two series of differing intensity. This is perhaps also the case 



* Zeitschr. Wiss. Mikrosk., xxvi. (1910) pp. 3S4-G. 

 t SB.k. Akad. Wiss., 1910, pp. 26-52 (11 figs.). 



