102 SUMMAKY OF CUKRENT RESEARCHES RELATING TO 



(5) Microscopical Optics and Manipulation. 



Common Basis of the Theories of Microscopic Vision, treated 

 without the Aid of Mathematical Formulae.* — J. Eheinberg explains 

 in four chapters the principles underlying the formation of a micro- 

 scopic image. These chapters were intended to form the commencement 

 of a little book dealing fully with each of the various theories of micro- 

 scopic vision, which have been, at any time, propounded, and the author 

 considers that their publication at the present time may be opportune, in 

 consideration of the interest recently aroused in the subject by Mr. J. W. 

 Gordon's paper.y The great feature in Mr. Rheinberg's paper is a 

 method of showing and explaining the action of a diffraction grating by 

 successive stages, beginning with two slote only. There are numerous 

 clearly drawn diagrams. The chapters are headed : (1) Elementary 

 Considerations ; (2) The Image of a Lens ; (3) Diffraction and Dif- 

 fraction Gratings ; (4) On Obliquity of Incidence and Cones of Light. 



Steinheil and Voit's ' Handbuch der Angewandten Optik.'J— This 

 important handbook on applied optics is less known in England than it 

 deserves to be. The first volume, which is the only portion as yet 

 published, contains some 814 octavo pages, 7 lithographic plates as well 

 as numerous illustrations. It is intended as an exposition of the methods 

 of calculating optical systems, and for their application to simple and 

 achromatic lenses. It consists of 5 chapters and 4 appendices. The 

 contents of the chapters are : (1) Reflection and Refraction of Light, 

 pp. 1-32 ; (2) Fundamental Peculiarities of a Dioptric System, pp. 33- 

 54 ; (3) Conditions for an actual Lens-System and Enumeration of 

 Mistakes to be avoided, pp. 55-66 ; (4) Computation of a Lens and 

 Discussion of its Image Errors, pp. 67-143 ; (5) Achromatic Objectives 

 of Two Lenses, pp. 144-206. The four appendices, which are partly 

 due to Dr. Seidel, deal with the mathematics of geometrical optics, and 

 include various tables of reference. 



Hauswaldt, H. — Interferenzerscheinungen an doppeltbrechenden Krystall- 

 p]atten im convergenten polarisirten Licht photographisch aufgenommen. Mit 

 einem Vorwort von Th. Liebisch. Magdeburg, 1902. 



Strbhl, K. — Strenge Theorie der Lupe. 



[The author gives some notes and explanations on M. G. Quesneville's 

 Nouvelle Theorie ale la Loupe (Paris, A. Hermann, 1902). They concern 

 the magnifying power of loups, Microscopes, and telescopes.] 



Zeit.f. wiss. Mikr., XIX. (1902) pp. 32-4 (1 fig.). 

 Thompson, S. P.— Some Experiments on the Zonal Aberration of Lenses. 



Arch. Neerland. [2] VI. (1901) p. 747. 



(6) Miscellaneous. 



Cantor Lectures, 1902 : Glass for Optical Purposes.§— The lecturer, 

 Dr. Glazebrook, devoted the first of the series of four lectures to an 

 explanation of the defects of a lens (spherical aberration, astigmatism, 

 coma, distortion, chromatic aberration), and of the chemical com- 

 position of optical glass. The second lecture showed how the defects 

 were rectified in a modern microscopic objective. The third lecture 

 dealt similarly with a photographic lens ; and the fourth with telescopic 

 objectives and combinations of telescopic and photographic lenses. The 



* Zeitschr. f. wiss. Mikr., xix. (1902) pp. 1-32 (35 figs.). 

 t This Journal, 1901, pp. 353, 475. . % Leipzig, B. G. Teubner, 1891. 

 § Journ. Soc. of Arts, Nos. 2601-7, Oct. and Nov. 1902 (59 figs.). 



