39.(Pg. [64]) How do we estimate the power gained by a system of pulleys?
40.(Pg. [65]) What is represented by [fig. 5. plate 5]?
41.(Pg. [65]) How does the wheel operate in increasing power?
42.(Pg. [65]) How is this compared with the lever?
43.(Pg. [65]) How does a handle fixed to an axle, represent a wheel, [fig. 6]?
44.(Pg. [65]) How could we increase the power in this instrument?
45.(Pg. [66]) What other forces besides the power of men, do we employ to move machines?
46.(Pg. [66]) What will serve as an example of an inclined plane?
47.(Pg. [66]) In what proportion does it gain power? ([fig. 7.])