180 REPORT—1899. 
than at any other observing station) with a marked bi-diurnal effect, as 
shown by Bessel’s interpolation formula, which for the months of October 
1898, to March 1899, is 
2/’-61 sin (9+ 295°°47’) + 0-73 sin (204+ 331°-57’) +030 sin (304 272757’), 
indicating a possible connection with the atmospheric pressure; the 
formula for the diurnal variation of which is 
0:0108 in. sin (04+ 49°32’) +. 0:0285 in. sin (29+4+163°2’) 
+0:0020 in. sin (39+ 26°4’), 
(6) That rapid changes in the vertical occasionally occur on a large 
scale, notably on 1898 December 5, 6 and 7, and 1899 January 7, and 
February 10 and 11. 
On December 5 (see diagram) after a dry period for a few days, a very 
heavy cloud formed at about 11 a.m. ; its eastern edge was clearly defined, 
and extended for about a mile to the Eastward ; shortly after noon very 
heavy rain began to fall at and to the west of the Observatory. The 
effect on the seismograph is seen in the accompanying diagram. 
Fig. 1. 
oS0 
7-30 Dec. 5 1898 V/ Yj 
: Wge Jabulations A 
MMMM 
(c) That air tremors occur every night, in spite of every precaution to 
ensure copious ventilation, and the prevention of convection currents. 
They begin at sunset with small movements, which rapidly become larger, 
but, although of variable amplitude during the night, do not show a marked 
maximum: they finally die away at sunrise. As a general rule the 
tremors are greatest when the fall of temperature during the night is 
greatest ; but this is not always the case. 
(¢) That on almost every day the westerly movement of the boom 
exceeds the easterly, indicating a gradual sinking of the land west of the 
instrument. 
We must conclude that this movement is only local, for if the whole 
island tilted in this way as a rigid body, land would appear on the east 
coast, which was previously submerged, and vice versd on the west coast, 
and up to now I have been unable to obtain evidence that such a thing 
has taken place. 
(c) That the earthquake effects are comparatively small, as will be 
seen from an inspection of the accompanying list. This makes us question 
whether it is possible for the ocean to act as a damper to earthquake shocks. 
hen records are forthcoming from Honolulu we may learn more of 
this subject. 
Beside the above five phenomena, there is another interesting point to 
