THE HISTOEY OF EXPLOSIVE AGENTS. 
379 
staples driven into the ground on either side of the piece of gun-cotton. The circuit- 
wire of the coil belonging to the last (eighth) chronoscope-disk was similarly fixed 
across the further extremity of the train, and the other wires were stretched across 
different parts at intervals of 1, 2, 4, and 6 feet in different experiments. 
In determining the velocity of transmission of detonation through tubes, wrought-iron 
gas-pipe of 1*25 inch (•031 m.) diameter was used; these pipes had very small perfora- 
tions bored into them at the desired intervals, so that the fine insulated wires could be 
passed transversely through the centre of the tube at those points. The wires were 
rigidly stretched by being wound round staples on each side of the tube, and the small 
disks of gun-cotton to which, and by which, detonation was to be transmitted were 
inserted into the tubes so as to be in close contact with the wires *. 
a. Detonation of dry gun-cotton , arranged in continuous roivs. 
The first three results obtained with continuous rows or trains of gun-cotton disks 
laid on their flat sides, exhibited considerable want of uniformity, i. e. the rate at which 
velocity was transmitted from one point to another (through distances of 1-4 feet, ‘304 
to 1 _ 216 m.) appeared to vary considerably in different parts of one and the same train, 
as well as in different experiments ; but this was evidently due to the employment of too 
stout a wire as the means of severing the circuit by the explosion. A much finer wire 
was therefore substituted for it ; but even with the employment of the finest procurable 
insulated wire, stretched as tightly as possible across the gun-cotton disks, it was obviously 
impossible to avoid very slight variations in the degree of rapidity with which the wires 
were broken by the detonation. Making allowance for this source of error, it will be 
evident from the following example that, in a continuous row of 170 disks (3 inches, 
= •075 m., in diameter and about 0 - 9 inch, =’0225 m., thick, and of the average weight 
of 2-6 ounces, 81T grms.), the detonation, measured at intervals of 6 feet in a length of 
42 feet (=12-76 m.), was transmitted with uniform velocity ; the measurement at the 
far extremity of the train was practically identical with the rate at which detonation was 
transmitted through the first 6 feet. 
Eate of progression of the detonation 
per second. 
Between 0' and 6'=17466 feet (5309-664 m.). 
„ 6' 
„ 12'=16815 
„ (5111-761 „ ). 
„ 12' 
„ 18'=17972 
„ (5463-488 „ ). 
„ 18' 
„ 24'=16252 
„ (4940-608 „ ). 
24' 
„ 30'=17511 
„ (5323-314 „ ). 
30' 
„ 36'=16099 
„ (4829-70 „). 
„ 36' 
00 
CO 
1" 
Jt— 
Jl 
OI 
» (5321-45 „). 
Mean=17122 feet=5136’60 m. 
* In carrying on these experiments I have received valuable assistance, at different times, from Captain 
SixeER, E.N., Major Maitland, E.A., and Captains W. H. Noble and Jones, E.A. 
3 d 2 
