We can readily measure the amount of heat in different things, and we know a great deal about how it acts, but we really do not know what it is. Heat is never by itself, but always with something else. We may have hot water, we may have hot iron, but no one has ever been able to divide the heat from the water or iron, and keep it divided.

We can easily make heat pass from one thing into another, but when things which have different amounts of heat are put together the heat will spread itself around so as to make all of the same temperature. A piece of iron put into fire becomes hot, because the warmth passes from the fire into the iron until both have the game amount of heat.

Most of the heat in the world comes from the sun. We can set fire to things by gathering the sun's rays and bringing them to a point with a lens.

Ice, you well know, "is water in a solid state. It is formed under the influence of extreme cold. It is a nearly solid, transparent, brittle substance, of a crystalline structure. It melts into water at the temperature of thirty-two degrees Fahrenheit."

In hot countries ice is made in a machine worked on philosophic principles.—Selected.