7 
24 O. N. Rood on Elongated Projectiles. 
But assuming the length of the projectile to be within the 
above standard American limits, it is still possible to increase its 
weight by adding matter about the point, which of course be: 
comes blunter. A ball was constructed of the same length as 
No. 4, but weighing 121-1 instead of 113-6 grains, the 7,°; addi- 
tional grains of lead being disposed about its point. As has be- 
fore been seen, the old ball with an initial velocity of 1128 feet, 
Lhe Curve of the Projectile.—The bounding curve of the pro- 
mathematical knowledge was, and is, exceedingly limited: the 
results of their experimental labors are on this very account the 
In two of the balls; with this exception, the coincidence was 
almost perfect: the curve of the first formed a portion of an el- 
lipse whose diameters were in the proportion of 5 to 0°9; in 
parallel with its axis than was the case in the others, conse- 
quently here it differed slightly from an ellipse. 
Form of the base of the Projectile —The base of most balls now 
used is either flat, slightly convex as in the American model, 
or more or less deeply concave as in all those constructed on the a 
expansion principle. — It is generally admitted that balls having 
a flat base and moving with a velocity greater than 1200 feet 
per second, leave behind them a perfect vacuum, which, in addi- 
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