SHRAPNEL EIRE.. 
189 
having therefore {a) a descending angle, and (b) a velocity impaired 
only by the resistance of the air. 
With a percussion fuze, it opens after graze, having (1) an ascending 
angle, and (2) a velocity considerably impaired, in addition, by the 
retardation on graze. 
(1) When a percussion shrapnel is burst through a 2-in. screen, it 
will be seen that the action takes place from 6 to 9 ft. beyond it. 
Graze on ordinary ground retards the shell more and causes a slightly 
quicker action of the fuze; the difference is, however, but slight, and 
the shell will be observed to act from 2 to 3 ft. after rising. It must 
therefore have at the time an angle of ascent instead of one of descent. 
The angle at which the shell rises after graze has never been care¬ 
fully ascertained; the writer has, however, observed a certain number 
of shell with time fuzes which burst, or struck targets after graze. 
Although the number and the care of the observations is hardly 
sufficient to warrant him in speaking conclusively on the subject, he 
believes that he is well within compass when he assumes roughly 
that with descending angles of less than 6° the angle of ascent is about 
one-fourth, and over 6° about one-third more. 
This angle of ascent would of course differ with a variety of con¬ 
ditions ; the consistency of the ground and the inclination of its plane 
being the two most important factors. 
With regard to the first, it is evident how great uncertainty in 
practice must be caused by it, even when the nature of the ground on 
which the object stands is well known; when—-as must very often be 
the case—it can only be guessed at, this uncertainty is immensely 
increased. 
The second would also greatly affect the regularity of practice. 
Suppose, for instance, the angle of descent to be 6° on level ground 
of ordinary consistency; that of ascent would be at least 8°. If the 
ground had a slope of 2° to the front, the angle of impact would be 
4° to the slope, and that of ascent 6° to the slope and 4° to the hori¬ 
zontal plane. With a slope of 2° in the opposite direction, the angle 
of descent would be 8° to the ground, that of ascent 10° 40' to the 
ground and 12° 40' to the horizontal plane. A small undulation of 
ground is sufficient to produce such an effect, and—as will be shown 
further on—the result would seriously affect the practice. 
(2) The retardation, and consequent loss of power, due to ricochet 
has already been shown (p. 187), and need not be further insisted 
upon here. 
The relative position of the cone of dispersion to the path of the 
shell has also been described (p. 177); it will, of course, be-the same 
whether the angle is ascending or descending. 
The ascending angle has the following effect: (1) the centre of the 
cone rises; (2) many—in some cases the whole—of the bullets start 
with an elevation. 
(1) The trajectory of the shell after graze is most difficult to describe 
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