THE EXHIBITION OB 1862. 
159 
crease of range is the resistance of the ah’, which, with high 
velocities, is very great, as may be gathered from the following 
experimental resistances to a ball two inches in diameter, ex- 
tracted from a table given by Dr. Hutton. With a velocity 
of 100 feet per second, it was ’174 lb. ; with 200 feet, '709 lb. ; 
with 900 feet, 94’106 lb. ; and with 2,000 feet, 102’362 lb. 
As the resistance is nearly proportional to the surface exposed 
to it, so, to gain increased ranges, it is necessary to increase 
the weight of the ball in a greater ratio than the surface ex- 
posed. For if two balls, one twice the weight of the other, 
exposing the same surface to the resistance of the air, are pro- 
jected with the same velocities, the heavier having twice the 
momentum or store of motion, has twice the power of over- 
coming* the resistance; that is, twice the range. With smooth- 
bored guns and spherical shot, the only way of accomplishing this 
(increased density being practically out of the question), is to 
increase the diameter of the shot, when the weight increasing 
as the cube, and the surface as the square of the diameter, the 
desired result is obtained, as far as the other circumstances will 
admit. 
With high velocities (as was shown by Dr. Hutton), the 
resistance rapidly rises in a variable ratio, which increases more 
and more above the square of the velocity ; so that, beyond a 
certain point, the increase is of no avail. 
In the rifle, however, the power of impressing a rotation gives 
us an advantage in overcoming the resistance of the air. 
For, as the tendency is for the axis of a rotating body to 
remain parallel to its original direction, if we project an elon- 
gated shot, it will be maintained with its point foremost during 
the flight, and, in proportion to its weight, will present a very 
small surface to the resistance of the air. Thus, if we compare 
Mr. Whitworth’s 3-pounder with the old 3-pounder, the 
weights of the shot are the same, but the diameter of the 
spherical shot is 2’91 inches, and. of the Whitworth 1'5 inch; 
the surfaces are, therefore, as 8*47 to 2’25; that is, the Whit- 
worth, with an exposed surface of only about one-fourth that of 
the 3-pounder, has the same weight wherewith to overcome 
the resistance offered by the atmosphere. Hence the enormous 
range that was obtained, — 9,688 yards, or upwards of 5| miles. 
It must not, however, be inferred from this that the pro- 
jectile may be indefinitely increased in length, and increased 
ranges thereby obtained. For as the powder is by no means 
instantaneously converted into gas, we very soon arrive at a 
limit beyond which it is useless to increase the charge; for it 
would not be wholly exploded before the shot left the gun, and 
we arrive at a point where the velocity is decreased without any 
corresponding gain. It is perhaps right to notice here the 
