382 
ME. E. A. ABEL’S CONTRIBUTIONS TO 
the uniformity of the rate of transmission were affected by the increased spaces which 
were allowed to intervene between the masses of gun-cotton. The fluctuations may, 
however, have been due in part to slight differences in the spaces, combined with small 
variations in the weight of the disks. The mean velocity of the detonation was =17,478 
feet (5243-4 m.) per second. It would appear from these results with spaced disks 
that the separation of masses of compressed gun-cotton from each other by spaces 
insufficient to arrest detonation may retard the rate at which this is transmitted from 
mass to mass, the extent of such retardation being of course determined by the relation 
between the size of the individual masses and the extent of spaces intervening between 
them. The separation of masses of about 2‘5 ounces (78 grms.) from each other by 
spaces of 0-5 inch (-013 m.) had a decided and uniform retarding effect upon the rate 
of travel of the detonation ; but with masses at least a third larger, the further increase, 
by one third, of the space intervening between them did not maintain a similar uniform 
retardation in the rate of travel, although there were indications of such retardation at 
some points along the train or row of spaced disks. 
c. Detonation of moist and wet gun-cotton . 
Gun-cotton disks containing about 15 per cent, of water, ranged in a continuous row 
(the dry disks weighing the same as those used in previous experiments), were found to 
transmit detonation with the same velocity as the dry material ; there appeared, indeed, 
some indication that the rate of travel was a little higher, the results obtained being 
all equal to the highest furnished by dry gun-cotton of the same density. Thus in one 
experiment the rate of travel in the first four feet was 18,416 (5524'8 m.), and in the last 
four 18,340 feet (5502 m.) per second, the mean velocity being =18,375 (5512-5 m.) 
per second. In the last 12 feet of the train the following rates were recorded : — 
Rate of travel of detonation 
per second. 
Between 16' and 20 , =18,880 feet (5664 m.). 
„ 20' „ 24'=18,416 „ (5524-8 „ ). 
„ 24' „ 28' = 18,040 „ (5502 „ ). 
In another experiment the mean velocity was =18,581 feet (5574-30 m.) per second, 
and in a third 18,433 feet (5529-9 m.) per second. 
With gun-cotton disks which were saturated with water (containing about 30 per cent.), 
but in other respects similar to those used in the former experiments, the rate of trans- 
mission of detonation was decidedly higher than with the dry disks. In one experiment, 
with a train 30 feet long, the mean velocity of transmission was =19,213 feet (5763-9 
m.) per second ; and the records from which the mean result was derived included one* 
* An interesting example was obtained, in the course of these experiments, of the manner in which the 
behaviour of gun-eotton, when exposed to the action of a detonation, as also the character of its detonation, is 
liable to be modified by a variation in the proportion of water with which it is impregnated. A number of 
disks ranging in weight from 2-5 to 2-7 ounces (78'0 to 84-24 grms.) when air-dry contained some of them 
