( 178 ) 
We get these equations, when for C, we substitute + 7? and 
— q° respectively in equation (4) and when we put C,=0, and 
this proves that the solutions of (13) fulfil the condition in question. 
In a further paper I hope to prove the two following theorems: 
I. If in a region of space p and v are functions of 2, y and z, 
and v satisfies the three following conditions: 
Ist » and its differentia! coefficients with respect to wz, y and z are 
everywhere continuous ; 
2ud with the exception of some points or surfaces in this space 
dv dv dv 
Ae =qvu—4n(A B 5 
de! ap? de Ss BAe ae 
3rd the products av, yv, ev, a? > y°—— en <*—— are nowhere 
infinite ; 
then v is the potential with respect to the point «, y and 
z of an agens, the density of which is g, while the potential 
function is expressed by: 
Ae-v + Ber 
gij Se i 
Il. If the same conditions as in I hold for g and v with this 
modification that — g? is substituted for g? and Asma for A + B; 
then v is the potential with respect to point x, y and < of an 
agens, the density of which is g, while the potential function is 
expressed by 
A sin (qr + @) 
On en 
T 
Hydrography. — Tidal Constants in the Lampong- and Sabaug- 
bay, Sumatra. By Dr. J. P. VAN DER STOK. 
I. Telok Betong. 
a. From April 23,1897 to April 22,1898 tidal observations have 
been made in the Lampong-bay on the road of Telok Letong, sit- 
uated in 5° 27' Lat. S. and 105° 16’ Long. E. at the 6 hours of 8 
and 10 a. m., noon 2, 4 and 6 p. m. 
As in the eastern parts of Sunda-strait the normal (i. e. oceanic) 
tides of the Indian Ocean must show a more or less gradual trans- 
