154. What is said of the expression, quantity of motion? Under what circumstances may a single impulse produce a great velocity? What examples have we of this? How is it with the motions that we see around us? What is said of the fall of bodies to the earth?
155. Give examples from muscular action. Give that of the arrow. Give that of gunpowder. What is said of the arrest of great velocities? Give the illustrations in regard to cannon-balls.
156. State and explain the feat of the anvil. Give examples from common efforts and labors.
157. Explain the communication of motion in the case of elastic bodies by Figs. 133 and 134. What is said of the reflection of motion?
158. What is said of the uniformity of motion? What of its uniformity in velocity? State by what means we calculate as to time.
159. What is said of the sun-dial? What of the hour-glass? What of Galileo and the pendulums? Explain the operation of the pendulum.
160. Explain Fig. 137. Explain the operation of the gridiron pendulum by Fig. 138.
161. What is said of the disposition of motion to be straight? Why is motion never straight, so far as we know? How can we make motion very nearly straight? Give the illustration of the bullet in full.
162. Give the illustration represented in Fig. 141. What is compound motion? Illustrate straight compound motion.
163. Explain Fig. 143.