To our distinguished countryman, Mr. Benjamin Robins, is due the credit of not only being the first practically to determine the enormous effect of the resistance of the air in retarding the motions of military projectiles, but also of pointing out and experimentally proving other facts with regard to this resistance, which will be noticed when considering the subject of the deviation of shot from the intended direction.
Result of Dr. Hutton’s experiments.
After him, Dr. Hutton made a great number of experiments upon the same point, viz., the effect of the resistance of the air upon bodies moving in that medium, both with great and small velocities; and the inferences which he drew from these experiments, although not absolutely true, are sufficiently correct for all practical purposes.
ON THE RESISTANCE OF A FLUID TO A BODY IN MOTION.
Circumstances affecting the resistance which a body meets with in its motion in a fluid.
The resistance which a body meets with in its motion through a fluid will depend upon three principal causes, viz:—
1st. Its velocity, and the form and magnitude of the surface opposed to the fluid.
2nd. Upon the density and tenacity of the fluid or cohesion of its particles, and also upon the friction which will be caused by the roughness of the surface of the body.
3rd. Upon the degree of compression to which this fluid, supposed to be perfectly elastic, is subjected, upon which will depend the rapidity with which it will close in and fill the space behind the body in motion.