142 
TOE CABINET OF NATURAL HISTORY 
REPLY TO SPORTSMAN’S REJOINDER. 
Messrs. Editors: — Your Correspondent, the “ Sports- 
man ,” certainly deserves much credit for his ingenuity in 
discovering the assailable points in my argument, and I 
acknowledge there may be much truth in some parts of his 
reply— but I regret he has not comprehended my diagram, 
and on this miscomprehension, has founded a system of 
reasoning and proof entirely irrelevant to the case. In my 
explanation of the problem, I supposed that one second of 
time might elapse from the commencement of pulling 
the trigger to the arrival of the load, which we will 
presume, to simplify the case, to be a ball, at the muzzle. 
This, I imagine, would not be much out of the way, for a 
sensible interval of time does ensue, after the finger begins 
to press the trigger, before the load issues from the barrel. 
When it has arrived at the very muzzle, and that muzzle 
still bearing full on the object, is the instant that my prin- 
ciple commences, the preceding being a mere introduction 
to the case. Let us imagine the gun and the object to be 
stationary, the ball will of course pass straight from one to the 
other. Let us suppose the bird alone to be in motion, at 
87 feet in the second, the ball will necessarily, if it take a 
second to fly from the gun to where the bird was at the mo- 
ment of discharge, be 87 feet behind the bird. The ball 
has in this case but one motion, and that a forward one. 
We will now in addition give it a latteral force. The 
gun, of course, is useless to the load after it has issued, 
and its movement may therefore cease. The ball depends 
for its forward projection, on the powder, and for its late- 
ral power, on the motion of the gun, and on no other 
possible cause. Suppose the ball be thrown from a mere hol- 
low and no barrel to exist, it would necessarily go straight 
forward from its chamber to the point toward which it was 
directed. If we give it a tube to pass thro’, up to the very ob- 
ject itself, it will reach the object it is true, but every inch it 
travels the route, it is receiving from this passage a lateral 
force which increases from the chamber, which we will 
take for the centre of motion, to the end, being from a 
unit, to 87 feet in the second. During the passage of the 
ball through a tube thus in motion, it will, whilst in the canal, 
perform a portion of an elipse — somewhat on the same prin- 
ciple that a body projected into the air will do it, to return to 
the same point from whence it started — being caused in one 
case, by the lateral pressure of the tube, and in the other, the 
attraction of gravitation, being in the latter instance a variable 
power, acting every instant in a different line according to 
the point over which the object is passing. In the case in 
dispute, the ball, so soon as it issues from the barrel, will 
pass in a right line, because gravitation is not considered, 
and the projectile has received all the forces that can influ- 
ence it. The ‘ Sportsman’ does not object to the swing of the 
muzzle of an ordinary gun being 10 feet in the second; or 
he may take any distance he may choose, for, a principle 
that is “ philosophically correct,” cannot be invalidated 
by a change of proportion alone. When the ball has there- 
fore arrived at the end of the barrel, it will have passed thro’ 
a given distance from the centre of motion, and acquired 
the sole lateral power of the part to which it may be at the 
instant attached, and if it remain attached, and the muzzle per- 
form a circle, would arrive at the same point again, in a time 
exactly according to the rate of motion of the part to which 
it was fixed. We will however let it loose during some part 
of the revolution, and how fast will it go, allowing it has 
received no impulse other than the circulatory motion of | 
the part. Certainly not more rapidly than the source of its 
motion, the muzzle, exactly as in “Sportsman’s” case of a 
man on a fleet horse, the object thrown, possessing precisely 
the same forward momentum, and returning by the power of 
gravitation to his hand, — or in the sailing ship, the object 
retaining a certain force parallel to the surface of the 
earth, besides the downward gravitation, and arriving at the 
foot of the mast, simply, because the foot of the mast is tra- 
velling at the same identical rate that the head is, and the 
falling body possessing precisely the same momentum. — 
Please tell me, Messrs. Editors, where the parallelism can 
be, between’these instances of “Sportsman” and the shoot- 
ing, for he certainly proves by them, that a projected body v 
receives the lateral momentum of the part from whence 
it issues, and no more. In his illustrations, he forgets that 
every point and body considered,' are moving at the same 
rate — whereas, in the shooting problem, the breech of the 
gun may be supposed a fixed centre of motion, around 
which the other bodies are revolving, and each possessing 
a different rapidity in proportion to its distance from the 
centre. Let me take another instance of the “Sports- 0 
man,” for I certainly desire to afford him every ad- 
vantage in my power. We will allow, the surface of the 
earth moves at the rate of 950 feet from west to east 
in a second of time, and will imagine a tower sufficiently 
elevated above its surface, the top of which, must describe a 
a circle as much greater than the surface of the earth as 
will require in the revolution round the axis, a circulatory 
momentum of 1000 feet in the second to preserve its rela- 
tive situation. Suppose a body to be projected from the earth 
at the foot, exactly towards the top of the tower. At start- 
ing, it possesses a lateral force of 950 feet in the second, 
and during a second, has arrived at the same height as this 
supposed point. Now where will it be? The answer is 
self-evident, it will be 50 feet behind the object towards 
which it was directly pointed at the moment of its departure. 
It still retains its side force of 950 feet in a second, and on 
returning to the earth at the expiration of the second second, 
will reach the point from whence it started, although that 
