This is a play-book and not a text-book of engineering a book full of fun, not fun at the expense of another, but the real fun and joy of making things. It is characteristic of the real American boy to design and fashion things with his own hands. To be sure, the creative instinct is more conspicuous in some than in others, but, be it apparent or latent, the instinct is really there in every boy and needs but the proper stimulus to bring it into active evidence. It is this stimulus that the following pages seek to furnish.