82 MECHANICS. 



Force. 



The force of any body striking against an obstacle, 

 is directly in proportion to its quantity of matter, 

 multiplied by its velocity. 



Velocity. 



The velocity of a musket ball is on an average 

 1600 feet per second, and its range half a mile; 

 whereas by theory its range ought to be ten miles. 

 The resistance of the air is the cause of its retardation. 



In velocities exceeding 1600 feet per second, the 

 resistance of the air is greatly increased ; hence the 

 absurdity of giving balls too great an initial velocity. 

 To give a bullet the velocity of 2000 feet per second 

 requires half as much more powder as to give it the 

 velocity of 1600 feet, yet after both have moved 400 

 feet, the difference between the velocity of each is 

 reduced to eight feet per second. 



A 24 pound ball, moving at the rate of 2000 feet 

 per second, meets a resistance of 800 pounds. As 

 the ball is diminished in size, the resistance is also 

 diminished, but only in proportion to the squares of 

 the diameter, whereas the momentum is diminished 

 in the ratio of the cube of the diameter. 



If a body could be projected upwards with the 

 velocity of 36,700 feet in a second, it would never 

 return, and as it receded from the earth its weight or 

 gravity would diminish. At present the greatest 

 velocity with which we can project a body, does not 

 exceed 2000 feet per second. A bullet, rising a mile 

 above the surface of the earth, loses -^oVo^ 1 P art f 

 its weight. 



The Solid of least resistance. 



A solid globe, of all figures, occupies the least 

 space ; on moving through air or water a long thin 

 sharp pointed rod receives the least possible resi&t- 



