NEWTON S PRINCIPIA. 239 



let fall from the lantern at the top of the cupola of the 

 same church, a height of 272 feet. The agreement be 

 tween theory and experiment was even more striking than 

 in the last experiments. 



The theoretical results are calculated on the supposition 

 that the resistance is proportional to the square of the 

 velocity, the density of the fluid, and the surface of the 

 sphere. The comparison with experiment serves to test 

 all these laws. We may, therefore, conclude that for such 

 velocities as those here experimented on, varying from 6 to 

 30 feet per second, and for spheres of radii varying from 

 J to 3 inches, and for the fluids of air and water, those 

 three laws are tolerably correct. 



Newton remarks that these experiments are more accu 

 rate than those he made with pendulums ; for the vibrations 

 not being very small, the body always excited a motion of 

 the fluid contrary to the motion of the pendulum on its 

 return, and thus the whole resistance appeared greater 

 than it really was. 



[See NOTE V.] 



