Figure 41. — Model of Redheffer's perpetual motion ma- 

 chine. This model was built by Isaiah Lukens for the Peale 

 Museum in 1813. Photo courtesy of The Franklin Institute. 



with the plank. I place on it this weight" (which 

 was a leaden brick, rectangular, about 3x4 inches, 

 and about one inch thick); the carriage stood still, 

 gravity being directly down, the weight equally 



distributed on all the wheels; the bed was then raised 

 and fixed at an angle of about 45 , and the weight 

 carefully placed on it; the carriage started and ran 

 some 10 feet or 12 feet, then stopped. 



81 



