In this case the first
effect of the explosion is to produce an enormous pressure on
everything confining it, and to advance the wadding through a
very small space. Here let us consider it as at rest for a
moment, and examine its condition. The portion of air in
immediate contact with the wadding is condensed; and if the
wadding were to remain at rest, the air throughout the tube would
soon acquire a uniform density. But this would require a small
interval of time; for the condensation next the wadding would
travel with the velocity of sound to the other end, from whence,
being reflected back, a series of waves would be generated,
which, aided by the friction of the tube, would ultimately
destroy the motion.
But until the first wave reaches the impediment at the
muzzle, the air can exert no pressure against it. Now if the
velocity communicated to the wadding is very much greater than
that of sound, the condensation of the air immediately in advance
of it may be very great before the resistance transmitted to the
muzzle is at all considerable; in which case the mutual repulsion
of the particles of air so compressed, will offer an absolute
barrier to the advance of the wadding.
Pages:
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62