380 
MR. E. A. ABEL’S CONTRIBUTIONS TO 
In an earlier experiment with the same description of disks, the mean velocity with 
which detonation was transmitted along a train 30 feet (9T2 m.) in length, the rate of 
travel being measured at intervals of four feet, was 16,871 feet (=506T3 m.) per second ; 
the rate of travel in the first four feet was 18,527 ( = 5558-1 m.), and in the last four 
feet 18,442 feet (5532 - 6 m.) per second. A third similar experiment gave a mean 
velocity of 18,234 feet (5470-2 m.) per second. 
In these experiments the separate 3-inch disks were just touching each other at two 
points of their circumference. The average weight of gun-cotton disks used was 2-6 ounces, 
= 10-4 oz. per foot (324-48 grms. per -304 m.) of the train. In another experiment a 
continuous train of uniform dimensions throughout was constructed of solid cylinders 
T25 inch (-031 m.) in diameter and 1-5 inch (-038 m.) long, which were laid on their 
sides, with the ends of each one in close contact with one end of another cylinder, so 
that the entire train was in the form of a continuous cylinder weighing 8 ounces per 
foot (249-6 grms. per -307 m.). The mean rate of transmission of detonation in this 
experiment was 18,868 feet (5660-4 m.); the rate of travel in the first four feet was 
18,180 (5454 m.), and in last four feet 18,950 feet (5685 m.) per second. 
In order to ascertain whether the rate of transmission of detonation would be affected 
by a very considerable reduction in the amount of compressed gun-cotton included in a 
given length of the train, cylinders of 0-9 inch (-019 m.) diameter were arranged in a 
continuous row, as in the preceding experiment ; their weight corresponded to 3 ounces 
(93 grms.) per foot (0-304 m.) of the train, or less than one third that of the disks used 
in the first experiments (and it corresponded to the weight of nitroglycerine used in an 
experiment to be presently described). In one experiment with these small disks the 
mean velocity of detonation was =18,546 feet (5638 m.) per second; in another it 
corresponded to 20,000 feet (6080 m.) per second. It will be seen that in these, and also 
in the preceding experiments with larger cylinders placed end to end, the velocity of 
transmission was higher than when the large disks were employed which rested on their 
broad surfaces, and only presented to each other comparatively small points of contact 
at their circumference. It was to be expected that the rapidity of detonation would be 
promoted by increasing the contact surfaces of the individual masses, and thus rendering 
the train as nearly as possible continuous. The individual records of velocities obtained 
at the different parts of the train (24 feet, =7’296 m., long) composed of the very small 
disks of gun-cotton presented greater variations than in the other experiments with 
larger masses ; this was no doubt caused by a greater variation in the degree of suddenness 
with which the wires were fractured, by the comparatively less violent explosions. 
In the second experiment with the very small disks, about one half of the train was 
constructed of cylinders having a central perforation of 0-25 inch (0-006 m.) diameter, 
those which composed the first half being perfectly solid. There were indications of a 
somewhat more rapid transmission of the detonation along the perforated part of the 
train. 
The foregoing experiments demonstrate that the rate at which detonation is transmitted 
