C o N T E N T S. XV 



LORENTZ (ii. A.) presents a paper of A. Pannekoek : "Some remarks on the 

 reversibility of molecular motions." 4-2. 



— Electromagnetic phenomena in a system moving with any velocity smaller than 

 that of light. 809. 



MAGNETIC DISTURBANCE (The daily held of). 313. 



MAGNETIC FIELD (On the doublc refraction in a) near the components of a quadruplet. I'J. 



MAGNETIC ROTATIONS (lavestigation of a sonrce of errors in measurements of) of the 



plane of polarisation in absorbing solutions. 760. 

 MANOMETER- and piezometertubes (The calibration of). 532. 

 MARTIN (k.) presents a paper of J. H. Bonnema : "A piece of lime-stone of the 



Ceratopyge-zone from the ihitch diluvium." oil). 



— presents a paper of I'rof. El"g. Dubois : "Deep boulder-clay beds of a latter 

 glacial period in North-Holland." 340. 



Mathematics. J. de Vries : "On complexes of rays in relation to a rational skew 

 curve." 12. 



— W. A. Versluys : "The singularities of the focal curve of a curve in space." 17. 



— Jan de Yries : "The harmonic curves belonging to a plane cubic curve." l'J7. 



— J. VAN DE Griend Jr. : "Eectifying curves." 208. 



— Extract of a letter of V, Wtlliot on the work of D. Bierens dk Haan : 

 "Theorie, propriétes, formules de transformation et methodes d'évaluation des 

 iutégrales dt'tinies." 226. 



— J. C. Kluyver : '-Series derived from the series -2" '-^^ . 305. 



m 



— P. H. ScHOUTE : "Centric decomposition of polytopes." 366. 



— r. H. ScHOüTE : "Flicker's numbers of a curve in S^." 501. 



— Jan de Vries : "On systems of conies belonging to involutions on rational 

 curves." 505. 



— Jan de Vries : "Fundamental involutions on rational curves of order five." 508. 



— W. Kaptevn : "On the dilierential equation of Monge." 620. 



— VV. A. Versluys : "The singularities of the fucal curve of a plane general curve 

 touching the line at intinity ff times and passing s times through each of the 

 imaginary circle jjoints at intinity." 621. 



— W. A. Versluys: "On the position of the three points which a twisted curve 

 has in common with its osculating plane." 622. 



— L. E. J. Brouaver ; "On a decomposition of a continuous motion about a fixed 

 point of S^ into two continuous motions about of -S'^'s," 716. Observation ot 

 Dr. E. Jahnke. 831. 



— Ered. Schuu : An equation of reality for real and imaginary plane curves with 

 higher singularities." 764. 



— P. H. SciiouTE : "Regular projections of regular polytopes." 783. 



— L. E. J. Brouwer : "On symmetric transformation of >S., in connection with 

 Sr and Sir 785. 



