39 ° 
FOREST AND STREAM. 
[Sept. 5, 1908. 
How Shot Emerges from the 
Sporting Gun. 
With the exception, perhaps, of yacht designing and 
handling, there is probably no sport which offers so 
many interesting and seductive problems to the scientific 
investigator as that of shooting, and the ease with which 
theory and dogmatism may be indulged in is only 
equalled by the difficulty of arriving at finality by ex¬ 
periment connected with what appear to be the most 
simple questions. The reason of the difficulties must 
naturally be referred to the very brief duration of even 
the longest period of time to be dealt with in any ballis¬ 
tic problem. The time elapsing between the fall of the 
hammer and the exit of shot from muzle is only some 
three-thousandths of a second, the time of flight from 
muzzle to a distance of five yards is rather under than 
over one-eightieth of a second, and yet within the sum of 
these two periods practically all the questions of velocity 
and pattern are determined and defined—that is to say, 
the form and speed of the shot charge during the first 
five yards are the criterion of efficiency at sporting 
ranges. Indeed, it would probably be more correct to 
say that what takes places during the first three feet of flight 
from the chamber is the determining factor. So far as 
time and pressure problems are concerned, the instru¬ 
ments in use up to the present may be regarded as fairly 
satisfactory in the hands of the expert; but the moment 
an endeavor is made to elucidate problems connected 
with the shape on emergence and ultimate dispersion of 
the shot charge, then it becomes necessary to actually 
see, or, better still, obtain a photographic record of what 
takes place. The art of barrel boring is in so advanced 
a state that the skillful barrel manufacturer can from 
experience predicate what the target result is likely to 
be from a certain combination of charge, cone, diameter 
of barrel, choke, and rigidity of metal; but for purposes 
of improvement and advance something more than the 
final result must be known, and the effect of each 
contributory factor must be investigated. Of the out¬ 
standing problems, the form of emergence of the shot 
from choked and cylindrical barrels seemed to the writer 
to offer a valuable field of inquiry. Electric spark pho- 
FIG. I. 
Head Wave 
FIG. 2. 
tographic methods of research had already been opened 
up by the work of Professor Boys, Lord Rayleigh, Mr. 
F. J. Smith, and others, including Professor Mach, 
and the following extract may be fitly quoted from a 
lecture delivered some fifteen years ago by the first- 
named investigator, Professor Boys, who published the 
result of his researches in a most valuable and practical 
form, at the British Association meeting in Edinburgh: 
“There is a point of interest to sportsmen which has 
given rise to a controversy which the spark photographs 
supply the means of settling. The action of the choke- 
bore has been disputed, some having held that the shot 
are made to travel more compactly altogether, while 
others, while they admit that the shot are less scattered 
laterally, as may be proved by firing at a target, assert 
that they are spread out longitudinally, so that if this is 
the case, the improved target pattern is no criterion of 
harder hitting, especially in the case of a bird flying 
rapidly across the direction of aim. I was unfortunately 
not able in the limited space and time that I have been 
able to employ to take photographs of the shot at a 
reasonable distance from the gun, but I have taken com¬ 
parative photographs at three or four yards only, in 
which every shot is clearly defined, and in which it is 
even easy to see on the negative where the shot have 
been jammed into one another and dented. The differ¬ 
ence in the scattering at this short distance is not suf¬ 
ficient for the results to give any information beyond 
this, that shot are as easily photographed as bullets, 
and that no difficulty need be apprehended in attempting 
to solve any question of the kind by this method.” 
Contrary to the opinion expressed by this inves¬ 
tigator, the writer had long maintained the view that it 
was necessary to take observation at shorter distances 
than the three or four yards above mentioned, as well as 
cit longer ones, and an installation was laid down, con- 
si sting of a dark chamber 15ft. long, 3ft. wide, and 9ft. 
high, provided with a door at one end pierced with a 
suitable aperture for the gun barrel to pass through, 
and at the other or target end provided with a mass of 
soft wood to catch the shot and permit none to rebound. 
In one side of the dark chamber, and at the same height 
fiom the ground as the axial line of the gun barrel a 
small hole is cut, and immediately behind this is placed 
the pair of copper terminals, forming the spark gap, 
across which a large plate condenser discharges and 
produces a short luminous spark of a duration a little 
more than one-millionth of a second. Upon the other 
side of the chamber, immediately opposite to the spark 
gap, a dark slide for the photographic plate is fixed 
upon a suitable rack, the sensitive side of the plate being 
of course toward the spark, from which it is distant 
exactly two feet. The dark slide being open and the 
sensitive surface of the plate unprotected, the effect of 
the electric spark passing across the gap is to exoose 
the whole plate, which then yields on development a 
uniform black negative. On the other hand, if any 
moving solid or other matter capable of obstructing the 
light from-the spark is interposed between the spark and, 
the plate, then, obviously, permanent shadowgraphs are 
produced on development, the clearness of outline de¬ 
pending upon the relation between the duration of the 
spark and the speed of the moving body. A little 
simple arithmetic will show what the duration of the 
spark must be to produce a sharp image of shot travel¬ 
ing at, say 1200ft. per second. If the disk of con¬ 
fusion or blur is placed at l-100in., then the exposure 
produced by the electric spark must be less than one- 
millionth of a second,- namely, .0000007 second. With 
one-millionth of a second exposure the movement 
amounts to fourteen-thousandths, practically l-70in., and 
this blur or disk of confusion is just allowable. It need 
scarcely be pointed out that the shadowgraphs pro¬ 
duced in this manner are on a somewhat larger scale 
than the original, the increase depending upon the rela¬ 
tive distances of spark gap to shot and shot to plate. 
In the installation used by the writer the spark gap is 
ltiin. from the line of fire—i. e., from center of shot 
charge, and the line of fire is Sin., from the photographic 
plate. 1 his means that the 12-bore wad is shown in the 
photograph as lin. in diameter, in place of ,738in., every¬ 
thing else being in the same proportion. The photo¬ 
graphs here shown must, therefore, be mentally trans¬ 
lated to three-quarters of their size to- realize actuality. 
As regards distance from muzzle at which photographs 
may be taken, there is a little difficulty about the 
adoption of distances much less than 2ft. as there is a 
tendency for the emerging gases to spread out laterally 
and obstruct the clearness of the pictures; moreover, 
with the photographic plates of the necessary rapidity 
there is at short ranges a tendency for the light pro¬ 
duced by ihe flash from the muzzle" to produce the fog 
of a general illumination. Shotgun explosives differ 
much in this respect, as can be easily observed by firing 
at night; but it was found that at a distance of 2ft. from 
the muzzle valuable records could be obtained free from 
the above defects, and the photographs here shown were 
taken at that distance. They are selected from a very 
large number of records, obtained with guns of different 
types of boring, different charges of powder and shot, 
1 
FIG. 3- 
