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[Large illustration]

INVENTING
FOR BOYS

BY

A. FREDERICK COLLINS

INVENTOR OF THE WIRELESS TELEPHONE

WITH NUMEROUS ILLUSTRATIONS AND
DIAGRAMS

NEW YORK
FREDERICK A. STOKES COMPANY
PUBLISHERS

Copyright, 1916, by
Frederick A. Stokes Company

All rights reserved

TO
JOHN ROLLER COLLINS
A THINKER OF THOUGHTS
NEW AND NOVEL

A WORD TO THE BOY

Every boy is a born inventor.

And since you are a boy it follows as the night the day that you have your share of inventive ability and you ought to make good use of it.

To find out some new way of making or doing a thing—for this is what inventing means—is the most fascinating game that I know of to take up a fellow’s time and thought and energy.

You may say how about wireless, or star-gazing, or baseball, or shooting, or chess, or any one of a dozen other pastimes and sports and I shall be bound to admit that all of them are highly entertaining and some of them instructive but inventing is all that the others are and besides it is constructive while they are not.

By constructive I mean that you take an idea that had its origin in your brain and this vague, intangible conception, which takes up no space, has no weight and is not bound by time, you build up step by step of wood and steel and like materials until at last you have created something out of nothing, or as nearly as it can be done.

To watch your invention grow, especially if you build it with your own hands, from the time you make the first rough sketch of your idea until it stands completed and in working order, gives you a wonderful feeling of pride and satisfaction for you are the creator of it and this means that you are more than a mere boy, greater than an ordinary man—that you are in very truth a demi-god.

These are the real pleasures of inventing but to make a success of it you have to drop back to earth again and take up the mean, the sordid part, and that is to try to make money out of it. And if you have an invention of merit you will have to forget that you are a demi-god and become a hard and fast mortal again or it will not be long before some other body owns it lock, barrel and stock; and then you will have a chance to start another idea rolling and to build up another invention.

In this book I have tried to point out to you not only how to invent, but how to make money out of your invention as well, and so, I say unto you, from the moment the big idea strikes you be as gentle as a dove and as wise as a serpent, to the end that your days as an inventor may be long and that any profits which may accrue from your invention will be yours instead of some one’s else. And now may peace be with you.

A. Frederick Collins.

Lyndon Arms,
524 Riverside Drive,
New York City.

CONTENTS

ILLUSTRATIONS

INVENTING FOR BOYS

CHAPTER I
GETTING AN IDEA

Almost every one has had, at some time or other an idea for a new invention or of how some old device could be improved.

To get an original idea for an invention is in itself a mark of genius, but it is not enough to make it a success and if you do not know how to develop it you are almost certain to give up before you have completed it.

And to give up a good idea and then find that some one else has thought of the same thing later, worked it up and made money out of it gives a fellow a most uncomfortable feeling about what might have been.

Now my purpose is not to tell you what to invent as much as it is to tell you how to invent and, if when you get an idea that you believe worth while you will follow it up step by step as I have outlined in this book you will at least save yourself time, worry and money and you stand a chance of winning fame, glory, and a bank account.

How to Get an Idea.—There is only one way to invent a new thing or to make an improvement on something that has already been invented and that is to get an idea.

Fig. 1. A POPULAR IDEA OF AN INVENTIVE GENIUS

And what, you may wonder, is an idea? It is easy to say that it is a notion that comes into your head, or a thought that springs into your mind. But I doubt if even a psychologist could explain just what an idea is or how one originates in the mind any more than a biologist could tell how the germ of life is retained in a seed and how it grows when it is planted.

One good thing about an idea, though, is that we don’t have to know what the mysterious thing is or how it springs into being in the mind. In this way an idea is very much like electricity—we don’t know exactly what it is but we do know a good deal about how it works and this is enough for our present purpose.

The First Raw Idea.—There are several ways by which you may get an idea for an invention but in any case the first raw idea, or inductive discovery, as it is called in philosophy, must and does come from something outside the mind, something that you have seen, heard, smelled, tasted or felt, and when your mind is in the right condition to receive an idea of this kind you will know it when it comes and grasp it very quickly, that is if you are a real inventor.

Fig. 2. WHERE THE BIG IDEA REALLY ORIGINATES

There are many kinds of raw, or original ideas and they show themselves in various ways. You may get a very vague idea of an invention, or of an improvement, or it may be a clean cut one on the jump; it may be a very valuable idea or it may be a wholly worthless one, but it is generally easy after you get one to enlarge upon it, as we shall presently see, and to build up in the mind’s eye a structure so that you can guess pretty nearly whether you will have a palace, an architectural monstrosity or a chicken-coop when it is done.

A first, or raw idea may come to a fellow, who is on inventing bent, in any one of several ways but chiefly when (1) he is conjuring up in his mind something which he has seen or heard; (2) when something happens by accident which shows him an effect or a result that is new, and (3) when he is looking at or working on some device or machine; and this last way is the one that is most productive of ideas for useful improvements.

As an example of getting an idea behold a young man rocking in a chair with closed eyes; he is thinking of nothing in particular but of a good many things quite vaguely. A thought of his sister packing her trunk—in the way a woman usually packs a trunk—comes into his mind and then an idea strikes him that it would be a good scheme for a trunk to have drawers in it like a bureau. The result of this raw idea is the wardrobe trunk as we know it to-day.

Accidental Discoveries.—Once in a long while some one hits upon an invention purely by accident.

A good illustration which covers the point was the discovery of vulcanized rubber. The story goes that Charles Goodyear happened to drop some crude rubber and sulphur on a hot stove at the same time with the result that it was made much stronger and more elastic than before.

Experiment showed that the vulcanized rubber could be made as soft or as hard as desired by using more or less sulphur and applying more or less heat. From this discovery of Goodyear’s has sprung the gigantic rubber industry of to-day.

Discoveries of this kind were often made in the early days of invention but the principles which underlie all of the sciences are now so well known that invention itself has been brought down to a scientific basis; and instead of inventors being long-haired, dreaming Micawbers they are generally men of education and genius too, trained along the lines they are working in and who look like clean-cut business men; and if they are successful inventors you may depend upon it they are business men.

When I say that they are men of learning I do not mean that it takes a college professor to be a big inventor; indeed very few college professors have the genius to be inventors and too many inventors have too little knowledge along the line in which they are working. Of the two genius is the greatest for it is bred in the bone while any one can educate himself.

To make the point clear here are three famous men of genius and who were largely self-taught.

Faraday who made the dynamo and motor possible was a poor, uneducated boy with a burning thirst for knowledge when he was apprenticed to Davy at the Royal Institution in London. Edison had about as little schooling as the law allows, but he taught himself science and he now stands head and shoulders above all the rest of the great inventors. And Marconi, a young fellow of 23, invented the wireless telegraph while the greatest scientists of the world could not do it until he showed them how.

Thought Out Ideas.—There are very few inventions which are complete when the first idea of it comes into the mind, but instead nearly all of them require thinking out, or deductive proof as it is called in philosophy.

This second process of thinking consists of turning the raw idea over and over in your mind so that you can judge whether it is good or not, how it will work out and other things about it, and to do this you must know as many of the facts relating to it as you can and when you have these all clear and catalogued in your mind your idea then takes on the aspect of an invention.

The two usual ways to get the needed facts are (1) to read up on the subject, and (2) to experiment along the line of your idea. Of course if it is your regular work that has called forth your first idea it is quite likely you will have all of the facts you need to go ahead and work the thing out; but if your idea is about a device, or a machine, or a compound you know nothing of your best plan is to read up on the subject and follow up your reading by making a number of experiments.

Reading up Your Subject.—In this day of public libraries it is easy to get books on any subject unless it is one on sunsets and sunsets don’t count in inventing—in fact nothing counts except the big idea, a shop or a laboratory to develop it in and burning the midnight incandescent light.

It doesn’t matter very much what invention you are working on you ought to read a first book on physics and one on chemistry and what’s more you should study them if you expect to ever invent anything of magnitude.

A book on physics tells all you need to know in the beginning about matter, force, motion, the principles of machines, the mechanics of liquids and gases, electricity and magnetism, sound, heat and light.

Suppose you have an idea for an electrical device, if you will read the chapters on electricity and magnetism in your book of physics you will learn what you ought to know first about these subjects and then if you need to go deeper you can get a more advanced book.

A book of the elements of chemistry tells about gases, acids, alkalies and metals and of their chemical changes, and you will find a little knowledge of chemistry of considerable use in working out many ideas. There are many books of physics and chemistry but Avery’s Elements of Physics published by the American Book Company of New York, and Remsen’s Elements of Chemistry published by Henry Holt and Company of New York are good books for a beginner to read.

Working Out Ideas by Experiment.—Though you may think long and hard and read everything you can find that has a bearing on your great idea, you will soon reach a point where you feel you would like to try it out, that is to build it up in reality so that you can see if it will do the work you want it to do or if it won’t do the work where the trouble comes in.

Generally speaking if it is a mechanical or an electro-mechanical scheme you begin by drawing this brain-child of yours on paper and then you make a model, or try to, and you add to it, take away from it, tear it down sometimes and at others you scrap it and build an entirely new one.

But usually it is some one part that needs patience and effort and skill put upon it and as you try out idea after idea, plan after plan and scheme after scheme you are not only almost sure to find just what you are looking for but very often experimental work will lead you to fresh ideas for other and even more important improvements.

Another curious thing I have found about experimenting is this: you may start out on a certain line and find that the result you want is so hard to get it seems hopeless to go ahead. Now if you quit it is all off but if you go on and on trying everything you can think of, keeping up your belief that the thing you are striving for must come and in your own ability to do that which you want to do, after long hours, or days, or weeks of constant work the result will come to you like a flash and just as though the guardian angel of invention hovered over you and put the desired thing right into your mind and hand. The moral is that everything comes to the inventor who keeps on experimenting and does not give up.

Ideas for Inventions in General.—Inventions may be divided into three general classes and these are (1) mechanical, (2) electrical and (3) chemical; and there are combinations of these classes as (a) electro-mechanical and (b) electro-chemical inventions and your idea may come under the head of any one of them.

Fig. 3. A MODEL SELF-INKING PRINTING PRESS

Ideas for Mechanical Inventions.—Inventions of a mechanical kind include nearly everything in the broad domain of physics but the term mechanical inventions is applied especially to devices that are worked by means of pendulums, springs, weights, levers, wheels and axles, pulleys and inclined planes, screws and pistons and which have to do with force and motion.

To work out an idea for a mechanical device if the latter is a fairly simple one, as a printing press, see Fig. 3, or a scroll saw, see Fig. 4, should not be a very hard thing to do because all of the parts can be easily seen and if you add a few parts to it and it does not work the fault can be readily picked and the part that is causing the trouble can be redesigned and changed until the whole device is made operative.

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

Where an electric current is used for some simple device a thorough knowledge of electricity may not be necessary but if your invention requires that a low voltage current be changed into high frequency oscillations which are in turn varied by the voice and these oscillations are sent out from an aerial wire, all of which is done in a wireless telephone, I should say that you ought to have a pretty fair understanding of the theory of electricity before you begin your experiments—that is if you expect to develop your invention into an apparatus of utility and hence of worth.

Ideas for Electro-Mechanical Inventions.—There are many devices that are partly electrical and partly mechanical, the operation of the one actuating the other and the other way about.

Fig. 7. A FIRELESS COOKER. THE HEAT IS WHERE YOU WANT IT

The electric bell, see Fig. 9, and the telegraph sounder, see Fig. 10, are types of simple electro-mechanical devices, while the telautograph, see Fig. 11, and the electrical gyroscopic compass for use on ship-board, see Fig. 12, are examples of the more complex electro-mechanical devices.

To work out an idea by bringing both mechanics and electricity to bear in the same device often makes the work much easier for sometimes the armature of an electromagnet or the plunger of a solenoid will operate to a better advantage than a combination of levers. But to use mechanics and electricity in the same device you must of course have a knowledge of them both.

Ideas for Chemical Inventions.—There is another class of ideas which require neither mechanics nor electricity for their working out. They are chemical compounds.

Fig. 8. A LOUD SPEAKING TELEPHONE LARGELY USED ON SHIP-BOARD

Suppose an idea comes to you to make a chemical solution for erasing ink, or to make a new high explosive. While the idea might be a good one you would have a long road to travel if you began experimenting and had no knowledge of chemistry and your road in the latter case would probably be straight up.

Trying out chemical compounds without knowing something of the reactions they produce is far more wasteful of time and money than puttering around with mechanical and electrical devices, especially when one’s line of business is selling ribbons, and besides it’s more or less dangerous too.

Should you get an idea for making an explosive more powerful than any yet invented, either dish the idea or pave the way by taking a course in advanced chemistry and even then your idea is liable to perish with you. Better let the Maxims or the du Ponts do it.

Fig. 9. A COMMON ELECTRIC BELL

Ideas for Electrochemical Inventions.—Just as there are ideas that call for the use of mechanics and electricity in a single device so there are ideas for processes that combine both chemistry and electricity.

The action of a common dry cell is electrochemical and so is electroplating. But there are a large number of chemicals and chemical substances that are produced by electricity such as nitric acid from the air, calcium carbide from which acetylene gas is made, carborundum which is used as an abrasive in the place of emery, and then there is the electrolytic refining of copper, the manufacture of aluminum, besides a whole string of other electrochemical inventions.

Fig. 10. AN ORDINARY TELEGRAPH SOUNDER

While it is quite safe to work along electrochemical lines still it takes a considerable amount of technical knowledge in these days to invent anything that the kultured German scientists haven’t thought of and worked out.

Protecting your Raw Ideas.—Just as soon as you have an idea for an invention write as clear a description of it as you can, read it to the members of your family, have them sign it and file it away as this is a record you may have to produce sometime in the future to prove your priority, that is that you were the first in time to conceive the idea.

As soon as you have your idea all thought out and have made a drawing, an experiment, a cardboard or other model, in fact anything that will show what it will do, at least to some extent, and so prove that you have really made a new invention, invite two or three of your trusted friends to see it.

Fig. 11. A TELAUTOGRAPH. A TELEGRAPH FOR REPRODUCING WRITING AT A DISTANCE

Having shown, explained and enthused over it have them go with you to a notary public and sign a statement to the effect that they have seen it; then have him put his signature and his seal on it. You have two years from the date you first showed it to develop and file an application for a patent on it but should you fail to do this within the above time limit any one else can take up your idea, if they know of it, work it up and get a patent on it.

Finally keep a note book and write down every thought you have about your invention, and every experiment you make in good black ink; draw pictures and diagrams and make photographs if possible of your work as you go along and put them in your book with the dates on them. This kind of a record will furnish you with what patent attorneys call the evidence of conception, and which will prove very useful in establishing your prior rights if you should ever get into an infringement suit.

Fig. 12. THE GYRO COMPASS OF A SHIP. A GYROSCOPE TAKES THE PLACE OF THE MAGNETIC NEEDLE

CHAPTER II
WORKING IT OUT ON PAPER

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.

Fig. 15a. AN ISOMETRIC PERSPECTIVE DRAWING OF A BOX

Fig. 15. B, A TOP PLAN VIEW OF THE BOX. C, A SIDE PLAN VIEW OF THE BOX. D, AN END PLAN VIEW OF THE BOX

To show the top, bottom, sides and ends of a box, or other device, you don’t need to draw out the whole thing in perspective but you can make a flat, or plan view of each part as shown at B, C and D in Fig. 15, that is an outline drawing shown as though you were looking squarely at it in the center and with the measurements marked upon it.

If now you will make a set of these working drawings of, say, a box and draw each part to scale, that is measured off in proportion, as shown in B, C and D, and saw out of a board the top, bottom, sides and ends and nail them together you will have a box like that shown in perspective at A.

Fig. 15. E, A CROSS SECTION VIEW OF THE BOX. F, DETAILED DRAWING OF THE HOOK

Plan views are easy to draw because they are formed of horizontal and vertical lines, and wheels are shown as true circles. After making your plan views, though, the safest way is to make a perspective drawing to the same scale for when you are looking at a square object as it really is it always appears larger than the plan views would indicate. But this is ahead of the story.

Now suppose you wanted to show how the box would look if it was sawed lengthwise through the middle. You simply make a cross-section view of it as shown at E and any one who knows how to read drawings will understand it. To show the hook on the front of the box more clearly it can be drawn separately as at F and this is called a detail drawing.

Exactly in the same way any device, apparatus or machine can be shown by top, side and end views and by cross-section and detail drawings.

Fig. 16. A SIDE VIEW OF A STEAM ENGINE

Just to see how something a little more complicated would work out on paper, let’s take the cylinder and steam chest of a steam engine. First draw a side view of these parts as shown in Fig. 16.

As the steam chest is a rectangle and every side of it is flat it can be shaded by drawing fine parallel lines spaced equally apart. The cylinder, pipes and rods are round, or rather cylindrical, and to get this effect these parts should be shaded with parallel lines drawn close together beginning at the top and bottom and making them ever farther apart as you get toward the middle and this will give it a rounded appearance.

Next draw the end view of the cylinder and steam-chest. Since the cylinder has been given a diameter of 3¼ inches in the side view, of course it must have the same diameter in the end view as shown in Fig. 17.

Fig. 17. AN END VIEW OF A STEAM ENGINE

By looking again at Fig. 16 you will see that the steam chest is 4½ inches long and that it is 2½ inches high but it is in the end view Fig. 17, that the width of it is shown. The end of the steam chest is shaded with straight parallel evenly spaced lines and the cylinder head is shaded with concentric circles, that is with circles equally spaced apart and having the same center.

Fig. 18. A TOP VIEW OF A STEAM ENGINE

In this and many other cases a side view and an end view give all the outside dimensions needed but sometimes a top view must also be made, and this is shown in Fig. 18.

Fig. 19. A CROSS-SECTION OF A STEAM ENGINE

While all of these views show the outside of the steam chest and the cylinder they give no hint as to how the inside is made. Suppose you had invented the steam engine of course you would know how the inside should be made and so you make a cross-sectional drawing of the parts as shown at Fig. 19, and then the construction and even the operation of the engine looms up as though you had turned a searchlight on it.

Fig. 20. THE SIDE VALVE SHOWN IN DETAIL

That is all of it will be clear except perhaps the slide valve and this is where a detailed drawing comes in to show a small part, or a part that is hard to understand by looking at the side, end and top views. The slide valve, see Fig. 20, is drawn in detail and the picture is made large and bold. The slide valve is made of a cast piece of metal hollowed out. It and the completed steam chest and cylinder are both drawn in perspective, that is just as the eye would see them if they were actually made of metal. The latter is shown in Fig. 21.

Fig. 21. AN ISOMETRIC PERSPECTIVE DRAWING OF A STEAM ENGINE

A Simple Way to Draw in Perspective.—Did I hear you ask how you can make a drawing in perspective? List and I will tell you the simplest way—a way so that you do it the first time you try.

Buy a quire of isometric (pronounced i-so-met´ric) cross-section paper 6 by 9 inches, at a cost of 15 cents, of any dealer in drawing materials. This paper is lined in faint colored ink in three directions, as shown in Fig. 22, and which represent length, breadth and thickness.

Fig. 22. A SHEET OF ISOMETRIC DRAWING PAPER. THE REAL SHEETS ARE PRINTED IN NEUTRAL TINTS, THAT IS, COLORS WHICH DO NOT INTERFERE WITH THE DRAWING

Now isometric comes from iso which means equal and metric which means measure, so isometric means equal measure and the three lines used in isometric perspective are at equal distances from each other. The lines which cross the vertical lines on isometric cross-section paper are 30 degrees from the base, or horizontal line and the vertical line is, of course, 90 degrees from the horizontal as shown in Fig. 23. Having everything at hand suppose you try to draw a square frame. Begin by making the first upright and you will see by looking at Fig. 23 that all you have to do is to draw three vertical lines and join the top and bottom by marking over the 30 degree lines. This done draw three more uprights in the same way and when you have these on paper it is easy to put beams on top or struts between them as shown at Fig. 24.

Fig. 23. FIRST STEP IN ISOMETRIC PERSPECTIVE DRAWING

As all the lines are of equal measure you can mark on the exact dimensions as shown in many of the isometric perspective drawings in this book. For a drawing of some device, or of a whole machine, to give to some mechanic to make for you the better way is to hand him a perspective drawing together with the top, side and end views, rather than the latter views alone, and then he will not need to figure out how they are put together.

Fig. 24. THE NEXT STEP IN ISOMETRIC PERSPECTIVE DRAWING

To show to a better advantage how isometric perspective works out look at Fig. 25 and you will see how the bearings of a crankshaft of a four cylinder gas engine stand out in a vertical line, up and down and in a horizontal line right and left as though they were real and made in three dimensions.

Fig. 25. A CRANK SHAFT DRAWN ON ISOMETRIC PAPER

How to Make Isometric Paper.—To make isometric perspective drawings you can get along without the cross-section paper described above though this is the easiest and most accurate way to get results.

But you can make these drawings on any kind of paper if you know how to use a protractor and measure of 30 degrees. To do it right you should have some drawing tools and if you are an inventor you should have them anyway.

Drawing Tools You Need.—For making drawings of any kind you should by all means have a drawing-board as shown at A in Fig. 26. As a drawing board must be perfectly square and made so that it cannot warp it is better to buy one of a dealer in drawing materials.

Fig. 26a. A DRAWING BOARD

A good board is built up of thoroughly seasoned strips of white pine glued together and fitted with end ledges; a small board say 12 by 17 inches on the sides can be bought for 50 cents or a little more and it will serve you well. A 12 inch triangular boxwood architect’s scale is shown at B in Fig. 26 and is much handier to use than a common rule.

Fig. 26b. A TRIANGULAR SCALE

A beginner’s set of drawing instruments consisting of compasses, with pen and pencil points, a ruling pen and a box of leads all in a nice pocket case, as shown at C, Fig. 26, can be bought for $1.25 and these compasses are easier to handle than the one shown in Fig. 14.

Fig. 26c. A SET OF INEXPENSIVE DRAWING INSTRUMENTS

But the chief instrument you need is a protractor, as shown at D, Fig. 26. This is a semicircle of brass, or of German silver, 3¾ or 4½ inches in diameter and costs 10 cents or 40 cents, according to the size and metal it is made of.

Fig. 26d. A PROTRACTOR FOR MEASURING CIRCLES AND ANGLES BY DEGREES

A protractor, as you may or may not know, is used to lay off angles and to measure angles in degrees. The curved part or scale of the protractor is divided into 180 degrees since there are 360 degrees in a circle. The figures start at both corners with 0 so that an angle of any number of degrees right or left can be marked off. Now the lines formed by marking off angles of 30 degrees are the only ones you will have to make for isometric perspective. To do this fasten a sheet of paper to your drawing board with thumb tacks at each corner and draw a straight line across the paper near the bottom. Put your protractor on the edge of the paper and the pencil line exactly as shown in Fig. 27; lay your rule so that its edge crosses the straight part of the protractor at the middle, marked A in the drawing and also on the line of the scale of the protractor marked 30 degrees and then draw a line on the paper along the edge of your rule.

Fig. 27. THE POSITION OF THE PROTRACTOR ON PAPER

This done place the protractor on the opposite and left hand edge of the paper and the horizontal line and lay your rule with its edge crossing the middle of the straight part of the protractor as before and on the 30 degree line of the scale and so that when you draw the line it will cross the other 30 degree line as shown in Fig. 27.

If now you draw another line at 90 degrees, that is vertically, between the two crossed lines, also as shown in Fig. 27, each of the three lines will be exactly the same distance apart in degrees. You can go ahead now and draw lines ⅛ inch apart parallel with each of the three lines and you will have a sheet of isometric cross section paper of your own making.

How to Draw Isometric Ellipses.—An Easy, Rough Way.—There is just one more little thing you should know about making isometric perspectives and that is how to draw disks, wheels and anything else that is circular in form so that they will look right and be right.

Fig. 28a. THE PROPORTION OF AN ISOMETRIC ELLIPSE

In isometric perspective everything that is round in reality is drawn in the shape of an ellipse, that is a closed curve that is longer than it is wide as shown at A in Fig. 28; there are different shaped ellipses but there is only one used for isometric drawing and this is always in the ratio of 1¼ to 2; that is if an ellipse is 2 inches long it will be 1¼ inches wide; an ellipse 4 inches long will be 2½ inches wide and so on.

An easy, though rough way to draw an isometric ellipse is to make a line as long as the diameter of the disk or wheel you intend to represent; draw another line which is the width of the ellipse through the center and at right angles across it, see A again and then draw the curved line around the end of them free hand.

Fig. 28b. HOW ELLIPSES STAND OUT IN RELIEF

How these ellipses are made to appear as if they were set either in a vertical or a horizontal position and at right angles to each other is shown at B in Fig. 28. The axis, that is the spindle, or shaft on which the disk, or wheel, is mounted, must always follow the 30 degree line running at right angles to the edge of the board or whatever it is supposed to be fastened to or goes through; and the thickness of the disk or wheel is always shown on the same sides as the thickness of the board or other part on which it is mounted, all of which is brought out clearly at B in Fig. 28.

How to Draw an Isometric Ellipse.—A Harder but More Accurate Way.—Begin by drawing a straight line as long as you want the longest axis of your ellipse to be, as shown at A B, Fig. 29. Divide this line into four equal parts. Now take your compasses and with the needle at the center of the line O draw a circle having the line as its diameter.

Fig. 29. HOW AN ISOMETRIC ELLIPSE IS DRAWN

Next start at A with your dividers and divide the whole circle into ten equal parts and then take your rule and draw a line from the point C on the circle through the point G on the diameter and produce, or extend it to the bottom of the circle; draw a line from D through G and extend it to the top of the circle; draw a line from E through H and extend it to the bottom of the circle when it will intersect the line C G at the point J; and finally draw a line from F through H to the top of the circle which will intersect the line D G at I.

Take your compasses and using G as a center draw the arc K A L; then using H as a center draw the opposite arc M B N; using the point J as a center, draw the arc K M so that its ends will meet the upper ones of the end arcs perfectly; using the point I as a center draw the fourth and last arc L N when the ellipse is completed.

When making isometric ellipses much care must be taken to make all the points and draw all the lines with the greatest accuracy as the slightest error will distort the whole thing.

How to Shade Drawings.—Besides the few hints for shading perspective drawings which I have given above there are certain ways to shade cross-sections and elevations to show whether it is made of metal, glass, wood, liquid, cork, carbon, insulation or other materials. There are also different kinds of shading to show fine and coarse fabrics and the various colors.

Fig. 30. A SHADING AND LETTERING CHART FOR DRAWINGS

The patent office has prepared a chart showing the shading that should be used to represent the different materials and colors and these are reproduced in Fig. 30. The letters of the alphabet both upper and lower case, as the capitals and little letters are called, which are used by mechanical draftsmen are also shown in Fig. 30. As these letters and figures are clear, easy to make and are preferred by the patent office they are good ones for you to use.

How to Make Electrical Symbols.—In making drawings, either for yourself or for the patent office, of electrical apparatus to show how it is connected up you do not need to draw out a plan view or a perspective of each part but you can make what are called symbols.

Symbols are simply a few lines or signs that stand for or represent a certain piece of apparatus; as an illustration suppose you want to show a dry cell, all you need to do is to make a couple of parallel lines, one shorter and heavier than the other like this:

and if you want to show a battery you make as many pairs of parallel lines as there are cells in this fashion:

And just so with every separate piece of electrical apparatus, and all of them are shown at A and B in Fig. 31.

Fig. 31a. A CHART OF ELECTRICAL SYMBOLS

[Large illustration]

Fig. 31b. A CHART OF ELECTRICAL SYMBOLS

[Large illustration]

How to Read Electrical Diagrams.—From the plates of symbols given at A and B in Fig. 31, you will see that the symbol for a battery is a pair of parallel lines as shown above, that the symbol for a motor is made in this fashion:

and that a switch is made like this:

now if you want to show a battery, a motor and a switch wired together all you have to do is to join the symbols with lines as shown at C in Fig. 31 and you will have what is called a diagram.

You can read a diagram, that is understand how it is connected up, in an instant for you can see at a glance how the wires run. Because the wiring is shown so simply and clearly diagrams of this kind are usually called wiring diagrams.

Fig. 31c. A SIMPLE WIRING DIAGRAM

In drawing wiring diagrams try to place each symbol in such a position that the connecting lines which represent the wires cross each other as seldom as possible, otherwise your diagram will be confused and it will be hard to follow out the circuits.

Some Aids to Drawing.—The following aid to drawing and designing was published in the English Mechanic and you will find it very helpful if your invention has to do with an automobile, aeroplane, or any large machine which is used or actuated by a person.

Fig. 32a. THE DIMENSIONS OF A MANIKIN

Make a manikin, that is a little jointed figure of a man as shown at A in Fig. 32. The figure can be made to any scale but 1 inch to the foot which is ⅙ full size is a good ratio to make it but it must of course be made to the same scale as the machine you are drawing.

To get the right proportions rule a sheet of paper a couple of inches wide and about 8 inches long so that the divisions will be ¹/₁₂ inch square and draw on this the different parts of the manikin as shown at B in Fig. 32. Now since every ¹/₁₂ inch on the paper is equal to 1 inch for a man 6 feet tall your manikin will be 6 inches high when it is jointed and complete.

Fig. 32b. THE PROPORTIONS OF A MANIKIN DRAWN ON CROSS-SECTION PAPER

The figure can be made of cardboard if it is to be used only a few times but thin wood, celluloid or hard rubber, or sheet tin, brass or copper will make a much more substantial one. Whatever the material that is used the edges of each part should be filed smooth; and when you rivet the parts together to make the joints the latter should work smooth and yet stiff enough so that the parts will stay in whatever position you place them.

Fig. 32c. A TRIAL POSITION OF THE MANIKIN

When you lay the manikin on your drawing you can see whether or not the levers are in the right places as shown at C and D in Fig. 32.

Fig. 32d. ANOTHER TRIAL POSITION OF THE MANIKIN

Making Cardboard Models.—In drawing out your invention you will often find that you can’t get the image you have in your mind’s eye down on paper.

There may be the movement of a lever, the turning of a wheel or the motion of a cam that you cannot quite see through and try as you will to work it out on paper the thing refuses to materialize. Under such conditions it would be a great waste of time and money to set about building a real model but there is an easy way out of the difficulty and that is to make a cardboard model of the device.

Just as an illustration take the case of an aeroplane. Say that your big idea is a scheme for controlling the elevating planes and the direction rudder; you have clearly in mind the use of an elevating plane on each side of the rudder and yet when you try to draw it out these two parts won’t fit together at all as you expected them to do.

When you reach this point get a sheet of heavy cardboard, shears, bottle of liquid glue, pins, matches or toothpicks, some thin wire, a few corks and a sharp knife.

Out of these materials you can build up the fuselage, as the body of the aeroplane is called; next you can fasten on the rudder and then the elevation planes; and when you have the tail-planes put together with real materials and actual shapes and sizes they will stand out in bold relief and you will have no trouble in making your drawings from the cardboard model.

Or suppose you have an idea for a gyro-motor such as are used for driving aeroplanes. Now in this motor the shaft to which the pistons are fastened stands still and the cylinders in which the pistons move revolve. It is rather a curious motion and not easy for a fellow who is not posted on mechanics to grasp offhand.

What’s the thing to do? Why, make a cardboard model of the mechanism using pins for the shafts and you will have a model that will look like Fig. 33, and when you turn the cardboard disk with the cylinders marked on it you will see at once exactly how the motor works.

Fig. 33. A CARDBOARD MODEL OF A GYRO ENGINE

And so it is with many other contrivances; when you come to any part that doesn’t seem to fit or is not clear, make a cardboard model and your troubles will vanish as dew-drops in the morning’s sun.

CHAPTER III
THE STATE OF THE ART

Taking it for granted, now, that you have drawn out your invention on paper and have made cardboard models of the more difficult parts so that you can see about what your device or machine will look like and how it will work your next move is to look up the state of the art.

What is Meant by State of the Art.—The state of the art means everything that has been published either in books, papers, or in patents about anything that has been discovered or invented, which has a bearing on your invention.

As an instance the state of the art of the dynamo electric machine, or dynamo as it is called for short, goes clear back to 1833 when Faraday made the experiment of passing a wire across the pole of a magnet and found that a current of electricity was set up in it—that is in the wire. Since that time hundreds of patents have been taken out and thousands of articles have been written about dynamos.

All of this information, or data as it is called, goes to make up the state of the art in the class of dynamos and all of the patents can be had and many of the articles too if you know how to go about it to find them and one of the purposes of this chapter is to tell you how to do it.

Use of the State of the Art.—You can easily understand that with all the thought that has been given to, and the experimental work that has been put on, dynamos to the end of bettering them it is a pretty hard thing to make an improvement that has not been made before, though it is still quite possible to do so.

Suppose, then, you had thought of and worked out on paper some improvement on the dynamo which you believed to be new and original and of great value. Certainly since you know that inventors like Edison, Brush, Weston, Thompson, Tesla, and a hundred other men almost as big, had applied themselves with diligence to dynamo problems during the last 40 years you would not care to go very far in spending your time or your money working on it until you learned whether or not some one before you had thought of and used the same principle.

Yet hundreds of beginners in the field of inventing work along in the dark because they do not know the state of the art, and always to their sorrow. So don’t be one of them.

How to Learn the State of the Art.—For the reasons I have given above you will see that it is bad practice to go beyond the point of working out your invention on paper before you know whether it is really new or not for though it may be entirely original with you, if it has been thought of and read before some learned body of scientists, or printed in some musty trade paper prior to the time you conceived the idea you haven’t the slightest claim to it, nor is it of the least value to you.

And so after you have thought out your invention and have made drawings of it the next step is not to apply for a patent as most patent attorneys will advise to do, or to have a model made as many model makers will tell you to do but to look up the state of the art and see where you are at.

Having a Patent Attorney Look it Up.—The easiest and quickest way to learn roughly the state of the art is to have a preliminary search, as it is called, made by a patent attorney, which means that he will look through the files of patents that have been granted by the United States Patent Office to other inventors for devices or machines of the kind you are working on.

To do this you must, of course, retain a patent attorney, that is employ him, and turn the drawings and written description of your invention over to him. Every patent attorney outside of Washington, where the patent office is located, has a correspondent or an associate, that is another patent attorney, who lives there and who acts for him when necessary.

This latter patent attorney will take your drawings and description to the library of the patent office, look over the files of patents there and pick out those which seem to him are most nearly like your invention.

He will get copies of these patents, send them to your patent attorney who will in turn hand them to you with your original drawings and you can then go over them and compare them and judge for yourself whether you have a really new invention or if it burned in the brain of some other inventor before you ever dreamed of it.

From the above you might infer that it would be a good scheme to employ a patent attorney who lives in Washington; but on the contrary it is better to have a patent attorney in your own city transact this business for you, if one is to be had, for then you can talk with him and you will learn many things you couldn’t begin to find out through correspondence.

Many advertising patent attorneys agree to make what they are pleased to call a free search for you—and do it while you wait, so to speak. A free search, or desk search, as it is dubbed by those who don’t make them, is of no value whatever for it is the snap-shot opinion, or rather a notion, of a patent attorney who is drumming up business by un-business like methods.

To show how absurd an opinion of this kind is just consider that there are 43 divisions of inventions in the patent office; each division, is split up into anywhere from a dozen to nearly 200 classes and that in some of these classes as many as 12,000 patents have been granted as in the case of the sewing machine.

And when you ask a patent attorney of this ilk to make a free search for you he will write back a letter in this tone of voice: I have very carefully considered your sketch, etc., etc. The first payment of fees necessary to start your case is $20 and upon receipt of this amount I will be very glad to carry the case forward, etc., etc.

All patent attorneys who advertise that they will make a search for you free of charge will also make what they call a special search for which they charge $5.00, and any other patent attorney will make one for the same price and which is, after all is said and done, only a preliminary search.

You can buy a copy of any patent that has been issued by sending 5 cents in coin—the government won’t take its own stamps—to the Commissioner of Patents, Washington, D. C., that is if you know the number and date of it and the name of the inventor to whom it was granted. The patent attorney who makes the preliminary search will send you several copies of the patents nearest like your drawing without extra charge as these are, or should be, included in your $5.00 fee.

When you get the copies of these patents go over each one carefully and see how nearly the pictures are like yours; then read the description of the invention, or specification as it is called, and compare it with your own statement, and, finally study the claims at the end of the specification and pick them to pieces for in these are to be found what has really been allowed to the inventor by the patent office.

The patents found by the patent attorney in making a preliminary search of the files and which are sent to you does not by any means represent the whole state of the art, but they serve a useful purpose as a starter. The reason it is not complete is because the patents are usually selected by patent attorneys in virtue of their similarity to the drawings you have submitted to him. Sometimes, to be sure, he reads what the specification says and if he is a real good patent attorney he will sift out a few of the claims, though this is usually due to his patent training rather than to any conscientious desire on his part to get at all the facts in the case.

But when you have applied for a patent on your alleged new and useful improvement and it is being scrutinized by the examiner in the patent office, he will look up the state of the art in all its devious ramifications for this is what he is paid to do by the people of the United States, though he thinks it is the officials in Washington who employ him. At any rate he has plenty of time to do it in and ample assistance to do it with.

Nor does he merely take a glance at the drawings, specifications and claims of your patent application and compare them casually with others that have been granted along the same line of endeavor, but, instead, when enough pressure is brought to bear, he will look up everything that has ever been published in all languages, including the barbaric ro,[1] since Adam was a boy.

At other times and for no reason at all, or so it seems, he will of a verity go to sleep on the job in his sub-cellar and let an application slip through his room in a few months, while he will spend years on another application of the same kind. Of course if you are the fortunate one you will be glad to get a patent granted so easily; your patent attorney is glad because he has your money in his pocket and the examiner is glad because he has made a friend of his glad.

To have everybody glad is a nice thing, you will allow, but don’t crow too soon for there is a hole in the average patent big enough to drive a horse and wagon through. If your patent is for an invention of genuine merit you will not be alone very long in the field and should you commence to make anything that looks like real money out of it you will find some other genius with an invention and a patent, as like yours as the other Siamese twin and if you don’t sue him he will sue you and then you can fight it out in the courts.

Even as right is always on the side of the army with the heaviest artillery, if there are enough shells, so, too, justice is always on the side of the inventor who has the smoothest patent attorney and the cleverest experts if they have enough ammunition in the way of some claims. While it requires skill to draw up good claims they can in any case be made better where the state of the art is known by yourself and your patent attorney.

How to Look It Up Yourself.—Whatever the nature of the invention you are working on you should read up its history from its earliest beginnings and in this age of papers, books and public libraries this is an easy, entertaining and profitable thing to do.

As an illustration take the art of flying and let’s suppose you are working on a new wing, or main-plane, for an aëroplane; if you will go over the list of books sold by book publishers, or consult the catalogue of a public library you will find books on flying, or aviation as it is called, that will give you a full account of the development of flying machines; and if you will get the right book it will picture and describe all the forms of wings that have been invented and patented up to the time the book went to press. Then there are weekly and monthly papers published which are devoted entirely to the theory and practice of flying and by reading these you will be able to keep right up to the entering edge of the art.

Now what I have said about flying is just as true of whatever else you may happen to be working on, for books and papers are printed and published about nearly every subject you can think of, from aviation to wireless telegraphy; by reading up on the subject of and allied to your invention you will soon have the history of it by heart and this makes up a large part of the state of the art.

Another and fortunate thing when you look up the state of the art a lot of other ideas will surge helter-skelter through your mind and if you are careful to write them down many of them will be of much value to you in the furtherance of your invention.

If you live in a large city it is an easy matter to look up the patents that have been granted for inventions in your class, for you will find an Index of the Patent Office in the public library which gives the number and date of the patent you want and the patentee’s name. The Index is published every year by the Unites States patent office and it gives the alphabetical list of the patentees and of the inventors to whom patents were granted for that year.

Fig. 34. THE OFFICIAL GAZETTE
Fig. 35. PATENT SPECIFICATIONS
Fig. 36. INDEX TO PATENTS

Having found the patent you want to look into, get the Official Gazette of the patent office for the same year and by looking up the number, or patentee, or invention, or all of them, you can easily locate an excerpt of the patent and then you can take a look at the drawing and read the principal claims.

The Official Gazette is published every week by the patent office and it contains a picture and a brief description of each patent issued for that week, together with the number and date of the patent, the name of the patentee and of the invention.

Should you require more information about a patent than is given in the Gazette you can look up a copy of the patent, or full specification as it is called, and these are bound in handsome volumes of 100 patents each, or at least, this is the practice of the New York Public Library.