LOCAL VARIATIONS AND VIBRATIONS OF EARTH’S SURFACE. 63 
The following list of waves recorded on— 
May 17, 1873 | May 8, 1876 | May 15, 1879 | May 27, 1882 
$s 1874 * 11, 1877 », 14, 1880 » 14, 1883 
9 12, 1875 » 10, 1878 Oe Fee bo | » 13, 1884 
May 18, 1885 
will show you that May never passes without some disturbance in 
the ocean of the same character as csi which we attribute to 
earthquakes; that is, periodic waves, whose interval is about 
twenty-five minutes. With the diskaietetisies which usually comes 
fro 
which came that enormous sea wave that was still 36 feet high 
when it got to Hawaii, and, as recorded on our tide-gauge, was the 
greatest ever known here. Not every August have we earth- 
quakes, but that month always takes the earth through a meteor 
stream on the 10th, and gives us more or less of disturbance on 
the tide register. In the diagram attached the barometer curves 
for that month for the past eighteen years are reproduced. _— 
curve is marked by great barometric disturbances, very many of 
them between the 6th and 10th of the month. In 1868, when the 
There were five of them betwe P 7°30 p.m., and 
the interval between the c of these waves was twenty-five 
ata which is the same period as the so-called earthquake 
The greatest marked a change in barometer of 0-045 in., 
aiid it took place at 7°30 p.m., just eight hours before the largest 
wave was recorded on the tide-gauge. On the following night a 
grand display of meteors was seen off this coas 
It is not my intention to detain you with references to the various 
periods of wave disturbances that appear year after year in the tide 
register, but rather to publish the list of dates so that they may be 
compared with other records, which at present I have no means 
doing, for want of such records from other observatories. 
Referring to the delicacy of astronomical instruments, it is on 
record that | Sir George Airy said he could see the vibrations in the 
earth caused by children running round the Observatory as he 
looked into the quicksilver, and see the passage of a train a mile 
off. Ihave myself often seen the mercury start suddenly into 
vibration, and then shortly after I would hear the sound of wheels 
in the streets near the Observatory, and I had to wait till eis 
were ea before I could go on with the observations, Vehicles 
