KONINKLIJKE AKADEMIE VAN WETENSCHAPPEN 
TE AMSTERDAM, 
PROCEEDINGS OF THE MEETING 
of Saturday November 30, 1901. 
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(Translated from: Verslag van de gewone vergadering der Wis- en Natuurkundige © 
Afdeeling van Zaterdag 30 November 1901, Dl. X). 
Contents : “Some observations on the resolving power of the MicHE.son echelon-spectroscope”. 
By Prof. P. Zeeman, p. 247. — “Considerations in reference to a configuration of 
SEGRE” (2nd Part). By Prof. P. H. ScHoure, p. 251. — “On the influence of dif- 
ferent atoms and atomic groups on the conversion of aromatic sulphides into sulphones”’, 
By Dr. J. J. BLANKSMA. (Communicated by Prof. C. A. LoBry DE BRUYN), p. 264. — 
“On function and structure of the trunkdermatoma”. By Prof. C. WINKLER and 
Dr. G. van RIJNBERK, p. 266. — “Contribution to the determination of geographical 
positions on the West-coast of Africa”. By C. SANDERS. (Communicated by Dr. 
E. F. van DE SANDE BAKHUYZEN), p. 274, 
The following papers were read: 
Physics. — “Some observations on the resolving power of the 
MICHELSON echelon spectroscope’, by Prof. P. ZEEMAN. 
§ 1. On a recent occasion ') I have given a few observations on 
this subject. The acquiring of some new data induces me to return 
to it in this place. 
In his “Investigations in optics” Lord RAYLEIGH *) expressed the 
wish that spectroscopists in possession of powerful instruments would 
compare the actual resolving power with that of which they are 
theoretically capable and remarked that a carefully arranged suc- 
1) Bosscua Collection of Memoirs. Archiv. Néerl. sér. IL. T. 6, p. 319. 1991, 
2) Phil. Mag. 1879, 1880. 
17 
Proceedings Royal Acad. Amsterdam. Vol. LV. 
