108 REPORT OF THE CALIFORNIA EARTHQUAKE COMMISSION. 
siderable increase in intensity at 13" 58.3", but it is not evident what it refers to. The 
time of the long waves is very doubtful. 
The instrument is an ordinary Milne horizontal pendulum with the beam pointing to 
the east; to the supporting column a second pendulum is attached pointing south; this 
is about 10 cm. long and carries a weight. A long light beam carrying the diaphram is 
attached at right angles to this pendulum, so that the two records are made side by side 
on the same photographic paper. The diaphrams are cut down to a width of 6 or 7mm. ; 
and the slit in the box, thru which the light passes, is closed at intervals of 2 mm., so that 
a series of white lines appears on the record. One of these white lines lies almost in the 
center of the record of the north component. 
Mauritius is slightly misplaced on the map (plate 1); it should lie in the southeast 
angle between the lines marking 20° S. latitude and the red north-south line, thru the 
antipodes of the origin and practically touching these two lines. 
