654 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Von Rohr's Image-formation in Optical Instruments from the 

 Standpoint of Geometrical Optics.* — This work, whose full title is 

 given below, forms the first volume of a treatise on the theory of optical 

 instruments. It is dedicated to Professor Abbe, and the preface has 

 been written by Dr. Czapski. It is divided into ten chapters, as follows, 

 the names of the respective contributors being given in square brackets : — 



I (pp. 1-35). The claims of geometrical optics. [H. Siedentopf .] 

 II (pp. 36-82). Calculation-formulge. [A. Konig and M. von Rohr.] 



III (pp. 83-123). Abbe's geometrical theory of the optical image. 



[E. Wandersleb.] 



IV (pp. 124-207). Realisation of the optical image. [P. Culmann.] 



V (pp. 208-338). Theory of spherical aberrations. [A. Konig and 



M. von Rohr.] 



VI (pp. 339-372). Theory of chromatic aberrations. [A. Konig.] 

 VII (pp. 373-408). Calculation of optical systems on the basis of 



the theory of aberrations. [A. Konig.] 

 VIII (409-465). Prisms and prism-systems. [F. Lowe.] 

 IX (pp. 466-507). Ray limitation in optical systems. [M. von 



Rohr.] 

 X (pp. 508-547). The ray-path through optical systems. [M. von 

 Rohr.] 

 Many of the chapters are followed by collections of historical and 

 bibliographical notes. 



Diffraction-Image and Absorption-Image.f — K. Strehl has found 

 that S. Apathy's attitude towards the diffraction theory of microscopic 

 vision is not always understood, that he is even accused of " attacking 

 the Abbe theory of microscopical image formation." He states that 

 Apathy does not dispute the Abbe theory, but that he only limits it. 

 Apathy is of opinion that the ordinary microscopic image may be, as it 

 were, a superposition of three images, quite different in their nature, i.e. 

 of a diffraction-image in Abbe's sense, of a refraction-image, and of an 

 absorption-image. He ascribes the chief function to the last named 

 image. K. Strehl endeavours to make the views of himself, Apathy and 

 Abbe clear on these points. 



Michaelis, L. — TJltramikroskopische TJntersuchungen. 



Virchow's Arch./, pathol. Anat., Bd. clxxix. (Folge 17, Bd. ix.) 



1905, pp. 195-200. 

 Walker, J.— Analytical Theory of Light. C. J. Clay (London, 1904) 432 pp. 



(6) Miscellaneous. 



Optical Properties of Glasses produced by Chance Brothers.} — 

 By the courtesy of Messrs. Chance Brothers and Co. we are enabled to 

 give the following table of the optical properties of the glasses produced 



* Die Bilderzenguug in Optischen Instrumenten vom Standpunkte der geome- 

 trischen Optik. Bearbeitet von den Wissenchaftlichen Mitarbeitern an der optischen 

 Werkstatte, von Carl Zeiss, P. Culmann, S. Czapski, A. Konig, F. Lowe, M. von 

 Rohr, H. Siedentopf, E. Wandersleb. Herausgegeben von M. von Rohr. Berlin : 

 J. Springer (1904) 8vo, 587 pp., 133 figs, in text. 



t Zeitschr. wiss. Mikrosk., xxii. (1905) pp. 1-10. 



X See also Catalogue Optical Convention, 1905, pp. 2-3. 



