Fig. 4. A VELOCIPEDE SCROLL SAW WITH BORING ATTACHMENT
Of course if the machine is a more complicated affair in which there are pistons, valves and the like as in an air-pump, see Fig. 5, or an ordinary engine, see Fig. 6, it is liable to develop internal—or perhaps infernal would be more fitting—troubles that are sometimes very pertinacious and hard to overcome.
Fig. 5. A STANDARD SINGLE CYLINDER AIR PUMP
The easiest and best paying way to begin a career of inventing is to hit on an idea to improve some simple device that either makes for safety or for saving, for convenience or for lessening mental or manual labor. But if you should happen to get an idea for something big and hard don’t give it the go-by, but follow it up along the lines which I have indicated in this book and you will stand a pretty good chance of finally working it out to a successful conclusion.
Ideas for Electrical Inventions.—Ideas for inventions in which electricity and magnetism are used are generally harder to work out than those of a purely mechanical kind for the reason that the cause in the first case which produces the result you want cannot be seen, whereas the cause in the second case which sets up the effect you want is always visible.
But electrical inventions are like mechanical inventions in that they may be very simple, such as passing a current through the heating element of an electric cooker as shown in Fig. 7, or it may be quite a complex piece of apparatus as for instance a loud speaking telephone for use on ship-board as shown in Fig. 8.
Fig. 6. A HORIZONTAL STEAM ENGINE