Inventing for Boys

by A. Frederick Collins

But this much is certain if you are going to experiment the right way you must know something about the right way to experiment. No one should expect to work out to a successful conclusion a new machine or apply a new improvement to an old machine if he knows nothing of the first principles of mechanics or about mechanical movements, and by rights he ought to have some knowledge of machine design.

And the above statement is just as true of electrical inventions. A worker who does not know the difference between a binding post and an alternating current need not expect to progress very far with an invention of, say, an electric block signal system—unless he calls in an expert to help him; but what he should do is to study the principles of electricity and magnetism, learn the various currents that can be used and what apparatus and instruments are needed for utilizing these currents.

The same thing applies to inventions in chemistry in that to work intelligently you must know about the properties of substances, chemical change and acids, bases and salts. And with electro-chemistry both a knowledge of chemistry and electricity are needed.

It is easy to see that it would not be possible in the limited space I have here to say more than a word or two about the subjects of mechanics, electricity, chemistry and electro-chemistry when each requires a whole chapter to explain it even in a rough way and a whole book to explain it thoroughly. But there are a few things I can tell you about them that will put you on the right track and then I shall give you the names of some books that will be of great service to you when you are in need of them, and with your help we’ll make a real inventor of you.

How to Experiment with Machines.—Any one who possesses the slightest bent for mechanics can work out improvements on devices like egg-beaters and monkey-wrenches and feel their way as they go along.

But when it comes to designing and building real machines where numerous levers, gears, and springs are combined to make a working unit you should by all means read up on the subjects of work, energy and power, learn about the six mechanical powers—and the action of machines in general. The following definitions will give you an idea about all of them.

Work, Energy and Power.—A wheel will not turn of its own accord but if it is moved round by some force applied to it such as the hand, a coiled spring or a motor, work is done. In fact whenever a thing is made to change its position work is done.

The power to do work is caused by energy; energy is developed when some force is applied and can be stored up in bodies as when a ball is thrown. When the energy stops acting, or is used up, there can no longer be any work done. Energy can be transferred from one body to another, as from a clock-spring to a wheel, or from one wheel to another wheel; and energy can be transformed, as the chemical energy of a battery into the rotary energy of a motor or from steam into mechanical motion.

The unit of work is the foot-pound and this is the work done to raise one pound one foot high. The rate of doing work is the horse power and a horse power is equal to lifting 550 foot-pounds in a second, or 33,000 foot-pounds in a minute.