218 
GOLD MEDAL PRIZE ESSAY, 1880 . 
passes through the crest* * * § ’—the distance of burst remaining constant, 
increases the spread along the crest, diminishes the area of ground 
covered in rear and also reduces the angle of drop of the lowest bullets 
clearing the parapet. 
If now the object of the entrenchment is to be nullified by destroying 
the parapet, clearly common shell must be the projectile used; and 
if by searching out and destroying the defenders, it is equally clear 
that shrapnel ought to be the projectile. The first idea may at once 
be set aside: for to destroy an earthen parapet to any sufficient 
extent with our present field service common shell (9 and 16-pr.) is 
impossible, the projectiles being deficient in the two essentials for such 
purpose—namely, penetrative power and capacity for bursting powder—f 
and even if replaced by still more powerful field shell, J the latter 
would yet be unequal to the task, unless a way is discovered of substi¬ 
tuting gun-cotton, dynamite, or some such violent explosive for the 
present burster. 
If the entrenchment is to be searched out by shrapnel, two points 
have to be fixed—namely, the best distance of mean burst from the 
crest, and the best height of the mean trajectory above it. § 
There can be no question that it is preferable to burst the shell com¬ 
paratively close, because the effect desired is not chiefly in depth or in 
height, but in width along the crest; and by short burst, the height 
of the trajectory being properly adjusted, the main number of bullets 
can be got to pass close to the crest, while, further, their striking 
velocity will be greater, enabling them better to work through the 
earth. || The best precise point of burst, as regards spread of bullets, 
it would not be possible to indicate unless we knew exactly the 
average dispersion of the bullets in a section of the cone; nor 
would it be any advantage to define it precisely, seeing that our 
present time fuzes are not adjustable to a short difference of distance : 
for example, at 1850 yds. range they do not permit of less increase 
or decrease in length of burst than 75 yds. Other advantages of close 
burst are that it causes the ground in rear of the parapet to be further 
and better covered by bullets, so interfering with freedom of move¬ 
ment for supports, &c., and that it enables the point of burst to be 
more readily judged of, for correction in firing. We therefore consider 
20 yds. short to be about the best point of mean burst, but under this 
we think it should not be reduced.^ 
* To lower it further than this would he unadvisable. (See after). 
f We have no results of experiments on this head to refer to, but the following is given in the 
Prussian “Artillery Drill Regulations” for German guns:—“Tegel, 1878. Penetration into 
sand parapet by both light and heavy field common shell, at 437 yds. range, 39*4 ins.; crater* 
19*7 ins. deep, 59*0ins. broad and 59*0ins. high.” 
X Probably the 13-pr. under trial will give satisfactory penetration. 
§ When shrapnel is burst by percussion fuze, its effect, even under favourable circumstances, is 
very much reduced, from the diminished velocity and angle of ascent of the bullets after graze of 
the shell: we therefore set it aside in the present question, as unsuited and inferior to time 
shrapnel. 
|| A few inches of earth, however, suffice to stop shrapnel bullets. 
•|f Bursting 20 yds. short gives a diameter of cone at the crest of 9’4ft. The Prussian “ Artillery 
Drill Regulations ” recommend 27 yds. and under, as the best distance of burst. 
