37.(Pg. [97]) What two circumstances combine, to lessen the weight of a body on the equator?
38.(Pg. [97]) Why could not this be proved by weighing a body at the poles, and at the equator?
39.(Pg. [98]) What is a pendulum?
40.(Pg. [98]) What causes it to vibrate?
41.(Pg. [98]) Why are not its vibrations perpetual?
42.(Pg. [98]) Two pendulums of the same length, will not, in different latitudes, perform their vibrations in equal times, what is the cause of this?
43.(Pg. [98]) To what use has this property of the pendulum been applied?
44.(Pg. [99]) What change must be made in pendulums situated at the equator and at the poles, to render their vibrations equal?
45.(Pg. [99]) What do the vibrations of a pendulum resemble, and why will it vibrate more rapidly if shortened?
46.(Pg. [99]) In the revolution of the earth round the sun, what is the position of its axis?