THE HISTOEY OF EXPLOSIVE AGENTS. 
387 
periments in various other directions, regarding the influence exerted by the physical 
character or mechanical condition of an explosive body upon its susceptibility to deto- 
nation. 
The comparatively limited quantities of nitroglycerine at my command have com- 
pelled me to suspend for a time further experiments with that substance ; I hope, 
however, at some future time to have the opportunity of determining the rate at which 
detonation is transmitted by confined nitroglycerine, and of comparing it with gun- 
cotton under the same conditions, as well as with other explosive agents. 
g. Transmission of detonation by tubes. 
Several experiments were made for the purpose of comparing the rate of trans- 
mission of detonation by gun-cotton disks arranged as described in the foregoing, and 
by widely separated masses, through the agency of tubes. The mode of operating was 
as follows: — Iron gas-pipes, clean inside, and either 1-25 or 1*5 inch (T031 or ‘037 m.) 
diameter, had pairs of small holes drilled into them at intervals of 2 feet (-608 m.) and 
3 feet 3 inches (1 metre) from each other, sufficiently large just to admit of the inser- 
tion of the fine insulated wire, and so placed that the latter, when thrust through both, 
was stretched across the interior of the tubes at its centre and at right angles to its 
length, being tightly secured to pegs fixed in the ground on either side of the tube. 
Disks of suitable dimensions to fit the tube were inserted, so that two, weighing toge- 
ther T5 ounce (46 -8 grms.), were placed against each wire. In the wider (T5 inch, 
*037 m.) tubes the charges and wires were 2 feet apart, and in the 1-25 inch (-031 m.) 
tube they were 3 feet 3 inches (1 m.) from each other. The initiative detonation was 
produced at one end of the tubes by means of 2 ounces of gun-cotton. The rate at 
which it was transmitted from the starting-point (or initiative explosion) to the first 
charge in the tube was somewhat variable, ranging between 10,000 (3000 m.) and 
13,000 (3900 m.) feet per second; the subsequent transmission along the tubes, from 
charge to charge, proceeded at a tolerably uniform, but considerably reduced rate, the 
average being 6000 feet (1800 m.) per second. The following is an example of the 
observations recorded, with employment of a tube T5 inch ('037 m.) diameter, the 
charges being separated by intervals of 2 feet : — 
Eate of transmission 
in feet per second. 
From the initiative detonation to the charge 
2 feet distant 9922 (2976-6 m.) 
From the charge at 2 feet to that at 4 feet=6693 (2607-9 „ 
„ „ 4 „ „ 6 „ =5320 (1596-0 „ 
„ „ 6 „ „ 8 „ =6957 (2087-1 „ 
„ „ 8 „ „ 10 „ =6854 (2056-2 „ 
„ „ 10 „ „ 12 „ =5648 (1694-4 „ 
„ „ 12 „ .„ 14 „ =5246 (1573-8 ,, 
3 e 2 
