(421 ) 
the corresponding quantities Ò and et) by 0, and 0, and by «‚ 
€, then we have, neglecting the molecules which surround a point 
immediately : 
or 
7 re 
—24r 9 9 a 
fF 7 yr r® dr sin p dp dO fo ur dp 
—2 or 
e ee „3 
~ 
peter not 
5 a r°drsin p dp dO ) 
li 
Prof. Lorentz?) has deduced, that w (his quantity a) is inver- 
sively proportional to the root of the temperature. And though both 
the way in which I have arrived at the conclusion that the ab- 
sorption is inversely proportional to the third power of the tempe- 
rature, and that in which Prof. Lorentz found that it is inversely 
proportional to the root of the temperature, are but rough approxi- 
mations yet these results differ too much, to attribute this only to 
the neglections. 
Therefore an incorrect assumption must have been made some- 
where. And if so I should doubt in the first place the correctness 
of the assumption, that for all internal motions the increase of the 
energy must be proportional to the energy of the progressive motion. 
I should therefore suppose that in collisions there are influences 
felt which cause the energy of the internal motions, which bring 
about radiation, to increase more at a rise of the temperature than 
the energy of the progressive motion of the molecules. 
Mathematics. — “On rational twisted curves”. By Prof. 
P. H. ScHoure. 
1. Let Pi, Po, Pa, 24, . « . be successive points of a given twisted 
curve &; then we may consider the centre of circle P, Po Ps lying in 
plane P; Po Ps as well as that of sphere P Po Ps P,. When the 
") Proc. Royal Acad. of Sciences, Nec, 1899. Pag. 322. 
2) Versl. Kon, Akad. v. Wet. April 1898, DI, VI, blz, 559, 
