A. As the lightning runs down the tree, it develops the latent heat so rapidly, that it carries the bark of the tree along with it, while it seeks to escape.
Q. Why are boughs of trees broken off by lightning?
A. The mechanical force of lightning is very great; and when the flash strikes a tree, it will often break off the boughs by the force with which it strikes against it.
Q. Why is an electric shock felt most at the elbow joint?
A. Because the path of the fluid is obstructed by the joint: and the shock felt at the elbow is caused by the fluid leaping from one bone to another.
CHAPTER III.
Q. What is the third chief source of heat?
A. Chemical Action.