( 5354 ) 
— 
4 1 EE I 1 
n—8 Wen Sarde aken ask 2n-l 
(n — 5)? (e= IS 20.0. A NI ee 
| 
| 
(n — s)s (n — s-+1)s Nn — 1)s 2n — 1) | 
t 
and this differs from zero, it being the product of all possible dif- 
ferentes of the s+7 numbers nen — att, 7°. 2 n— 15 ene 
and no equal ones appearing among them. 
According to the final result obtained in this way the character- 
istic numbers of the locus of the centre of hyperspherical curva- 
ture Zj for the normal curve N;, are respectively 
2n—1, èn, 4n—7, 5n—138, Gn—21,.... 2n—1, 
~ 
from which ensues that they do not change if taken in reversed order. 
In particular we find for 
N= 
De 
n= 
n= 
n= 
n= 
n= 
n= 
n=1 
Bo 
KG 
pk 
Mo S 
Be 
oy 
9 
15, AT 
21, 18, 13 
2: 27, 25, 21, 15 
. . 17, 24, 29, 32, 33, 82, 29, 24, 17 
. 19, 27, 33, ‘a 39, 89, 87, 33, 27, 19. 
“ 
wo N 
ho 
Or 
Ù 
hi 
4 
Or 
do 
“I 
SOON ADAH Wo WO 
MB 
MS 
ht 
Or 
me 
“I 
ew ™ 
With this the table inserted in the preceding paper referring to 
the general rational skew curve of minimum degree can be compared. 
Physics. — “Equations in which functions occur for different values 
of the independent variable”. By J. D. VAN DER WAALS JR. 
(Communicated by Prof. J. D. VAN DER WAALS.) 
S 1. Let us imagine an electric vibrator at a distance r from a 
reflecting plane. If we wish to construe the equation of motion of that 
vibrator at the moment ¢ we shall have to take into consideration 
that forces act on the vibrator, which it has given out itself and which 
have then been reflected by the plane. These forces are determined 
