698 MYRON L. FULLER 
site of Kingston, and seriously damaging smaller areas built on the 
limestone reef. In the 200 years following this great shock the island 
was shaken from time to time by minor disturbances, some of which 
were of some intensity, but no record seems to have been kept until 
the latter part of the last century. The records available to the writer! 
covered the period from February 19, 1880, to November 25, 1906, 
during which 163 shocks were felt. Their distribution, which is 
shown in the accompanying table, indicates a maximum in the autumn 
and winter months with a minimum in the spring and summer months. 
The activity shown in the last column is computed by assuming that 
two shocks of Intensity I are equal to one of Intensity II, and that 
two of Intensity II equal one of Intensity III. In other words, I 
equals one, II equals two, III equals four, IV equals eight, etc. 
From the table it will be noted that the activity is 198 in the night 
hours (6 P.M. to 6 A.M.) as compared with 150 in the day (6 A. M. 
to 6 p.m.). The principal activity is from 2 to 5 o’clock in the 
morning with a lull at daybreak followed by a marked increase in 
the activity from 7 until 9. From 9 until 1 there are very few shocks, 
but from 2 to 4 the number is again high, after which it drops to a 
very low point from 5 to 7 o’clock. In the evening there is a strong 
rise between 8 and 10 o’clock, after which there is a falling off until the 
2 to 4 o’clock period the following morning. This early morning period 
of activity (2 to 4 A. M.) corresponds with one of the minima of the 
diurnal variations of barometric pressure. The forenoon period of 
low activity, from 9 to 11, corresponds with the forenoon maximum; the 
afternoon period of intensity, from 2 to 4, with the corresponding 
barometric minimum. Up to this point the disturbances agree with 
that postulated by the advocates of greatest activity during barometric 
minima with least activity during the maxima. The evening 
period of barometric maximum, which according to theory should be 
a period of minimum activity, however, is in reality one of great 
activity, while the least activities of all are found at daybreak and 
sunset when theoretically they should be of intermediate activity. 
These variations are not confined to the Jamaica earthquake, but 
have characterized others, especially the New Madrid earthquake 
of the Mississippi Valley in 1811, the record of the shocks of which 
* Maxwell Hall, published in the local press, February 18, 1907 
