1886.] = The Flood Rock Explosion. 137 
THE FLOOD ROCK EXPLOSION. 
BY WILLIAM HOSEA BALLOU. 
ro greatest artificial earthquake in history occurred on Sat- 
urday morning, October 10,at 11 h. 14 m., standard time. 
The point of disturbance was Flood rock in East river, on the 
imaginary extension of Ninety-third street of New York city. 
The earthquake was projected by means of 300,000 pounds of 
dynamite and rackarock powder arranged in twenty-two miles of 
metallic cylinders. It was entirely submarine in character, and 
surface damage was prevented by a tamp of fully 10,000,000 
cubic yards of salt water. Asa spectacle it was simply an Ice- 
landic or Yellowstone geyser on an extended scale—a sudden 
rise of water and gaseous smoke to a height of 150 feet for a 
length of 400 feet and a maximum thickness of 100 feet at the 
base of the column. The flying rocks and débris sketched in 
illustrated newspapers are the fickle inventions of inane minds. 
The column of upheaved water was so enormous that all solid 
bodies were hidden from vision. The explosion was comparable 
to a very good earthquake. 
Inadequate observations —Seismological observations were taken 
at various points, but the arrangements for so doing were inade- 
quate and quite primitive. This is a statement of fact, not reflect- 
ing in any manner on the observers. In the first place there 
were no seismometers or seismographs in this country. In the 
second place the engineer corps and scientific corps did not act in 
conjunction with each other, and the latter received no telegraphic 
warning of the exact moment to expect the shock. In the third 
place observers were not stationed at sufficient distances from the 
center of disturbance to measure the length of radii of earth 
vibrations. Had there been seismographs located at Buffalo, 
Montreal, Philadelphia, Washington, Portland, Me.; far out at 
sea, or at intervals on a direct diameter, say 1000 miles long, the 
exact length of the radii might have been determined. Further- 
more, seismographs make an intelligible record with the pencil 
which none of the observers secured. 
Results of scientific observations —The record obtained by- the 
Scientific corps, however, was exceedingly interesting and valua- 
ble. There were a number of astounding as well as expected 
results. . The instruments used were the seismoscope, the tele- | 
