The process as here briefly described seems simple enough, but we must not forget the enormous size of these pieces and their tremendous weight. They would be difficult enough to handle when cold, but much of the work is done while the pieces are at a white heat so that the men who control and operate the machinery that handles the big forgings must keep their distance. The casting, annealing, and tempering operations are performed with the piece in vertical position, and lofty machines and cranes are required to deal with these tall castings. A visit to a plant which manufactures big guns is bound to impress the visitor with awe and give him increased respect for the men who are able to handle such huge masses of metal and also for the men who have conceived and developed such gigantic operations. CHAPTER XXI ANIMATED MACHINERY IN MARKED contrast to the massive machinery and apparatus described in the last chapter, and fully as wonderful, is a class of machinery to which we might apply the term “animated.” By this we do not mean manikins or toys, but certain higher types of machines which seem to be possessed of powers that we should expect to find only in living beings--machines that have a sense of touch, sight, and hearing--machines that will reason out a mathematical problem; that will talk; that have the equivalent of a memory. In this broad classification we may include such widely different machines as the motion-picture camera and projector, and that mysterious mechanism which seems animated with strange powers of its own--- the gyroscope. MATHEMATICAL MACHINES