1886, ] Scientific News. 93 
ton, the results of his observations on the transmission of shock 
from the Flood rock explosion. 
The air-line distance between the observatory in Cambridge 
and Flood rock is 190 miles, and the observations were timed as 
follows: Disturbance first seen, 11.17.14; instant of maximum 
disturbance, 11.18.03; disturbance ceased, 11.20, 
The first vibration perceived was about a thousandth of an inch, 
and recurred at intervals for nearly two minutes, the greatest 
swaying of the mercury being over a space of one five-hundredth 
of an inch. : 
In this connection it is interesting to note that General Abbot 
reported that the shock from 50,000 pounds of dynamite, exploded 
in 1876 at Hallet’s Point, was transmitted through the drift for- 
mation of Long Island, at the rate of 5300 feet per second for 13% 
miles, Assuming the figures of the Cambridge report as correct, 
and that the mine at Flood rock was exploded at 11.14, seventy- 
fifth meridian time, it took the wave just 194 seconds to travel 
190 miles, or at the rate of 5120 feet per second. This is very 
near the rate of transmission observed by General Abbot, when 
the greatly increased distance is taken into account.—Zxchange. 
can the other three parts, The present part is edited by Drs. oo 
Mayer and Giesbrecht. oe 
— Carl von Gumppenberg, of Munich, is preparing a mono- Cla 
Staph of the geometrid moths of the northern hemisphere, and 
