44 



THE SEVEN FOLLIES OF SCIENCE 



must roll towards the circumference. The machine ought, 

 therefore, to turn incessantly towards that side." 



In his "Course of Lectures on Natural Philosophy," 

 Dr. Thomas Young speaks of these contrivances as fol- 

 lows : 



" One of the most common fallacies, by which the super- 

 ficial projectors of machines for obtaining perpetual motion 

 have been deluded, has arisen from imagining that any 



Fig. 7. 



number of weights ascending by a certain path, on one 

 side of the center of motion and descending on the other 

 at a greater distance, must cause a constant preponderance 

 on the side of the descent: for this purpose the weights 

 have either been fixed on hinges, which allow them to fall 

 over at a certain point, so as to become more distant from 

 the center, or made to slide or roll along grooves or planes 

 which lead them to a more remote part of the wheel, from 

 whence they return as they ascend; but it will appear on 

 the inspection of such a machine, that although some of 

 the weights are more distant from the center than others, 



