480 
from Cabinda and was lighted at night by an acetylene lamp with 
reflector. 
For the coordinates of the signal with respect to the observa- 
tion-pier I found by the measurement of azimuth and distance 
Ly=— (para > Saad Ay eee 07.24 
thus Signal Matuba gv —=— 5°17'6".2 4 == — 12° 10'7".4 
On Sept. 25, 1913 at Cabinda J] made a time-determination by 
means of 8 Ceti in the east and a Ophiuchi in the west. The 
telescope was twice pointed on each star in each position of the 
instrument, at mean zenith distances of 59° and 57° respectively. 
As correction of the Honwü chronometer I found: 
by & Ceti + 0'5435919 
« Ophiuchi 55.46 
Mean + Oh54m35s35 
On Sept 27 I then determined the azimuth of the signal by means 
of the greatest digression of r Ophinchi (the observation of that of 
0 Ceti failed) and found, counting from the north through the east etc. 
Azimuth Signal Matuba 21 = 353° 55' 26".1. 
From this and from gy’ — y = — 16'16" 1 Lealeulated from ArBRECHT 
and from ScHois in complete agreement: 
A’ —2= — 1' 43".65 
from which 
Longitude Cabinda Obs. P. = — 12°11'51".1 = — 0'48"47:.4 . 
An error of 30" in the azimuth causes in the longitude one of 
O'14 only. 
Physics. — “Note on the model of the hydrogen-molecule of 
Bour and Desire’. By J. M. Burgers. (Communicated by 
Prof. H. A. JuorENTz). 
(Communicated in the meeting of June 24, 1916.) 
Miss H. J. van Leeuwen has recently published a paper containing 
some notes on DegBijm’s calculation of the dispersion formula of 
hydrogen, which calculationis founded on the well-known model of the 
H,-molecule'). In that paper it is demonstrated that some of the 
vibrations which occur in DeBIJE'’s calculations are unstable, and 
methods are discussed by which the stability of the model may be 
ensured. 
1 These Proc. (1916) Vol. XVIIL p. 1071. 
