The next step after, and sometimes even before, you have thought out your great idea is to make a drawing of the invention it represents.
Nearly every one can do a little free hand drawing and this is a good way to make rough sketches to aid the mind in further developing thought.
But if you can make a simple working drawing of your device, that is a picture in which all of the parts are drawn in proportion, or to scale as it is called, the whole thing will stand out clearly before you and you can see where it is wrong and make the needed changes on paper before you try to build a model.
Fig. 13. A TWELVE INCH RULE
Fig. 14. A PAIR OF CHEAP COMPASSES
Tools for Making Simple Drawings.—To make simple working drawings, or mechanical drawings as they are called, all the tools you need are a good, straight 12-inch rule, as shown in Fig. 13, compasses as shown in Fig. 14, a medium hard lead pencil, a rubber eraser and some smooth white paper.
How to Make Simple Working Drawings.—At A in Fig. 15 is shown a drawing in perspective, that is as it would look to the eye, of a rectangular box, while B is a top view, C is a side view and D is an end view of the same box; of course the bottom and the other end and side cannot be seen but you can imagine pretty well that they are there if you try to.
