KONINKLIJKE AKADEMIE VAN WETENSCHAPPEN 

 • TE AMSTERDAM. 



PROCEEDINGS OF THE MEETING 

 of Saturday January 26, 1907. 



(Translated from : Verslag van de gewone vergadering der Wis- en Natuurkundige 

 Afdeeling van Zaterdag 26 Janunri 1907, Dl. XV). 



COlsTTEirTS. 



A. F. Holleman and G. L. Voerman: "«- and /3-thjpphenic acid", p. 514. 



J. D. van der Waals : "A remark on the theory of the '^-surface for binary mixtures", p. 524 . 



W. A. Wijtiioff : "The rule of Neper in the four-dimensional space". (Communicated by 

 Prof. P. H. SCHODTE), p. 529. 



P. H. Schodtb : "The locus of the cusps of a threefold infinite linear system of plane cubics 

 with six basepoints", p. 534. 



W. J. H. Moll-, "An investigation of some ultra-red metallic spectra". (Communicated by 

 Prof. W. H. Julius), p. 544. 



F. Schuh : "On the locus of the pairs of common points and the envelope of the common 

 chords of the curves of three pencils", (2nd Communication. Application to pencils of conies). 

 (Communicated by Prof. P. II. Schoute), p. 548. 



F. Schuh : "The locus of the pairs of common points of four pencils of surfaces". (Commu- 

 nicated by Prof. P. H. Schoute), p. 555. 



C. II. Wind, A. F. II. Dalhuisen and W. E. Ringer: "Current-measurements at various 

 depths in the North-Sea", (1st Communication), p. 566. (With one plate). 



F. SCHUH : "The locus of the pairs of common points of n-f-1 pencils of (n — 1) dimensional 

 varieties in a space of n dimensions". (Communicated by Prof. P. II. Schoute), p. 573. 



H. G. van de Sande Bakhuyzen: "On the astronomical refractions corresponding to a dis- 

 tribution of the temperature in the atmosphere derived from balloon ascents", p. 578. 



H. Zwaardemaker: "An investigation on the quantitative relation between vagus stimulation 

 and cardiac action, an account of an experimental investigation of Mr. P. Wolterson", p. 590. 



Erratum, p. 598. 



35 



Proceedings Royal Acad. Amsterdam. Vol. IX. 



