Inventors at Work, with Chapters on Discovery

The Latest Phonograph.

In October, 1905, I paid Mr. Edison a visit at his laboratory, when he showed me the phonograph as now perfected. Chief among his improvements is a composition for records which is much harder than the wax formerly employed, and may therefore revolve more swiftly with no fear of blurring. His reproducer is to-day a built-up diaphragm of mica, highly sensitive. In the reproducer arm is placed the highly polished, button-shaped sapphire which tracks with fidelity the grooves which sound has recorded on the cylinder. These features, combined in a mechanism of the utmost accuracy in make and adjustment, have opened for the phonograph a vast field in the business world. Some of the great firms and companies of New York and other cities now use phonographs instead of stenographers; a letter or a contract is dictated to a revolving cylinder with all the swiftness of ordinary speech. Afterward a secretary listens to the reproducer and writes the letter or contract at any speed desired. On occasion a cylinder bearing a message may be sent to a correspondent who listens to its words as sent forth from his own phonograph, no intermediate writing being required. Such instruments are extensively used in teaching foreign languages, learners being free to have a difficult pronunciation repeated until it is mastered. Mr. Edison has much improved the musical records familiar throughout the world; these are now produced in molds of gold with a delicacy that refines away the scratchiness of tone so unpleasant in earlier cylinders.

Telephone Messages Recorded for Repetition at Will: The Telegraphone.

As the fruit of rare experimental ability Mr. Valdemar Poulsen, an electrical engineer of Copenhagen, has invented the telegraphone. This instrument proceeds upon the fact that the electrical pulses of the telephone, minute and delicate though they are, can register themselves magnetically upon a moving steel wire but one-hundredth of an inch in diameter. The message is repeated as often as the wire is borne between the poles of an electro-magnet in circuit with a telephonic receiver. The accompanying figure shows the transmitter, the traveling wire, and the receiver as it repeats a message. The instrument in its latest form is illustrated opposite page 314. In supplementing the telephone most usefully, this apparatus brings a fresh competition to bear upon the telegraph. In many cases a man of business has preferred to telegraph rather than to telephone a message, because a telegram as a written record affords proof in case of error or dispute. Now suppose that through a telegraphone a broker offers six per cent. interest for a loan; his voice impressed on the wire, duly preserved for reference, identifies him as securely as would his signature on a written offer. Take a different case: a patient rings up a physician only to find him not at home; a message committed to a few yards of wire is listened to by the physician the moment he returns to his office. Take an example of yet another service: a letter may be dictated at Newark and recorded on a wire in Brooklyn, and there, at leisure, be put upon paper by an amanuensis. Or, better still, the message may be spoken upon a small, revolving disc of steel, and mailed to a correspondent who listens to its words as they roll out of his own graphophone. Young children and others unable to write may impress discs that tell their story to correspondents unable to read. So compact withal are the records of this instrument that they may soon give us not only music from the concert-room, and news from the telegraph office, but also the latest popular book.

A wire or a disc can repeat its record, vocal or musical, hundreds of times without loss of distinctness. To obliterate this record it only is necessary to pass the steel between the poles of a strong magnet.

The Gray Telautograph.

A telephone transmits a familiar voice so that its tones are at once recognized. By electrical means a telautograph reproduces writing at a distance so precisely that it may be as readily identified. To understand how this feat is accomplished let us begin with the transmission of vertical marks varying in length.

This task, as above illustrated, we perform by sending to a receiving pencil a current varying in strength between limits which correspond to the variations in length of our transmitted lines. The strength of this current, say 0.429 volt, decides where a mark will begin; the strength of that current in rising to say 27.5 volts, decides where that mark will end. To vary the strength of the current as desired we employ a square rod of aluminium, tightly covered with a thin copper wire insulated by silk wrapping. We place this rod beside our tablet, and scrape from its innermost surface the silk covering so as to leave the wire bare, while between its strands the silk remains intact as an effective insulation. Our rod is now a rheostat, whose use we shall presently discover. We are wont to think of copper as a good conductor, and so it is. Used in stout bars or thick wires it exerts but little resistance to an electric current, but when we employ a wire of but ¹⁄₂₀₀ of an inch in diameter, about the thickness of the paper on which this is printed, the narrowness of path reduces the pressure of a current so much that in the course of 375 feet it falls to one eighth. In like manner a glass tube of minute diameter might receive at one end water under extreme pressure, and at a yard distance send out a mere dribble. The copper wire of our square rod, or rheostat, is so thin that when connected at K with a source of 110-volt electricity, at V this voltage, or pressure, has sunk to but one twentieth of a volt.

Let us suppose our rheostat at V connected with a circuit extended to the receiving station. A wire, kept in this circuit, and moving up and down with our pencil, in a line always parallel with the side of our tablet, sends to the receiving station a current constantly varying in its pressure. As the wire passes from S to M the transmitted current rises from 0.429 to 27.5 volts.

At the receiving station we provide means whereby the current arriving at a voltage of 0.429 and rising to 27.5 will mark a vertical line the length of S M. A simple device for this purpose consists in a hollow coil of copper wire, or a solenoid, as electricians call it, through which circulates the arriving current, the coil being free to be drawn as a shell over a cylindrical electro-magnet. The degree to which such a coil, duly attached to a retractile spring, is drawn over a suitable electro-magnet, depends upon the strength of the current circulating in the coil. In the simple instrument we are using let us assume that when a current of 110 volts comes in, the coil moves to K, the end of its path; that when a current of 6.875 volts arrives, the coil moves to O; the receiving coil and the sending rheostat being marked with the same divisions. Our receiving coil actuates a pencil which accordingly marks a line of the same length and direction as that set down on the tablet of the sending instrument.

Let us next transmit between these two stations a series of horizontal lines. To do this we duplicate our first apparatus. We place a second rheostat along the foot of our sending tablet, not along its side, and slide a second wire along its bared surface with motions always parallel to those of the marking pencil. Thus a second current, going by a wire of its own to the receiving station there repeats through a second coil, or solenoid, the horizontal marks of our sending pencil.

We have now two sets of apparatus, alike in all respects, one sending rheostat at right angles to the other; one receiving solenoid at right angles to its mate. In the actual telautograph the rheostats are curved, as shown in the picture facing page 318, and they are so joined by levers that the up-and-down and sidewise motions of writing are accurately represented, from moment to moment, in the two varying currents sent afar. As these currents arrive they actuate a pencil, similarly furnished with levers, so that it moves in a path which exactly corresponds with that of the sending pencil. The apparatus has an ingenious ink supply, and a device to shift the paper as filled line after line. In its basic features the telautograph was invented by the late Professor Elisha Gray of Chicago. Its present form is largely due to the modifications and additions of Mr. George S. Tiffany of New York. The instrument is giving satisfactory service in thousands of banks, factories, hotels, business offices, and households. Its records at both ends of a line make it of inestimable value in many cases, as aboard a warship where orders of the utmost importance may be committed to its tablets. Exterior and interior views of the instrument are given facing page 318.

Machines Cannot Directly Imitate Hands: A Task Must be “Coded.”

Only a few machines deal with writing or its duplication, most machines perform quite other tasks at first wrought by the hands. Inventors have always gone astray when they have sought to imitate a hand process with anything like precision. On this point Sir John Fletcher Moulton, of London, says:—“Doubtless you have often had to send a message by telegraph to some distant country to which the rate charged per word is high. You write your message as tersely as may be, but even thus its length is formidable. You resort to your telegraphic code. It tells you that if you will change the phraseology of your message you can by a single code-word represent a whole phrase. You thereupon set to work to recast your message so as to make it capable of being expressed in code-words. When you have done so, you have not improved it as a message. It is less terse and less naturally expressed. If you were writing and not telegraphing, you would prefer to use it in its original form. But as now expressed, each of the phrases of which it is composed can be sent over the wires in the form and at the price of a single word, and the cost of the whole is but a fraction of what would have been the cost of the message as originally framed. It has been cast in a form suitable for cheap telegraphing. Just so with the inventor. He has to find a series of operations which, in their totality, are equivalent to the series of the hand worker. But each of these operations in itself need not be such as would in hand labor be suitable or even practicable.

“It is necessary and sufficient for him that they are suited to the new conditions, so that they can be well and easily done by mechanism, and that, taken as a whole, they produce the same result as the series which he is paralleling. He is re-writing the series in terms suited to mechanism just as the message was rewritten in terms suited for telegraphing. The meaning of the message must remain the same, but the terms used to express it are no longer those most naturally used in writing or speaking, but are those which can be telegraphed at least cost.

Sewing Coded in a Machine.

“To make my meaning clear, let me revert to the familiar operation of sewing. The hand process is plainly unsuited for mechanical reproduction. How is it to be translated into an equivalent cycle suitable for mechanism? In other words, how is it to be ‘coded’? This case is interesting, inasmuch as we have two independent solutions worked out at different dates and widely different in nature. The earlier invention imitated the hand cycle very closely. The thumb and finger of the right hand in the human being were replaced by pairs of pincers capable of taking hold of the needle and letting it free again, but to avoid having to follow the intricate movements of the human fingers in the operation two pairs of pincers were used, one on each side of the work, which passed the needle backwards and forwards through the fabric one to the other. Following out this idea the needle was pointed at both ends with an eye in the middle, and, as in hand sewing, it carried a moderate length of thread. The pair of pincers which held the threaded needle advanced to the fabric and passed through it to the other pair which took it and retreated so as to draw the thread tight and form the completed stitch. To form the next stitch the work was moved through the proper distance and the same process was gone through, the line of movement of the needle always remaining the same.

“There is not much ‘coding’ here. The new cycle imitates the hand-worker so faithfully that it benefits little by the advantages of mechanical action. As in hand work it can only sew with moderate lengths of thread, and must therefore have the needles re-threaded at intervals. Its superiority over hand labor is therefore so slight that it is doubtful whether such a sewing machine could ever have competed with, much less replaced, hand work. But it has one great merit. The needle mechanism is capable of being re-duplicated almost without limit, and the movement of the work which is necessary to direct the stitches for one needle will serve equally well for any number of needles working parallel to it. Hence the machine that would have failed as a sewing machine has survived and proved useful as an embroidery machine. The work is stretched between two rows of pincers and moved by the workman according to the stitches of the pattern. Each stitch is repeated by each of the parallel needles which work side by side at convenient distances, and thus as many copies of the pattern are simultaneously produced as there are needles. Each is a perfect facsimile of all the others, and as each copies faithfully the errors of the workman, this machine is entitled to the proud boast that its productions possess all the defects of hand work—an essential we are told of artistic beauty.

“What is the cause of the comparative failure of this attempt at a sewing-machine? It is evident that it is due to the retention of the feature of the hand operation by which the needle is passed from one holding mechanism to the other. The inventors of the modern sewing-machine on the one hand decided to work with a needle fixed in its holder and never leaving it throughout the operation. It at once followed that the needle and thread must, on the back stroke, return through the same hole through which they had entered the fabric, so that no stitch could be formed unless some obstacle were interposed to the return of the thread. Here the two famous and successful forms of the machine parted company. Both placed the eye at the point of the needle that the stroke might not be needlessly long, but while the lock stitch machine used a second thread to provide the necessary obstacle, the chain stitch machine availed itself of a loop of the original thread for that purpose. Thus in the lock stitch machine the substituted cycle became as follows:—

(1) The work is moved under the needle for the new stroke.

(2) The needle (which has an eye at its point through which the thread passes) pierces the fabric carrying with it the thread.

(3) A second thread is passed between the thread and the needle (by means of a shuttle or its equivalent) when the needle is at its lowest position.

(4) The needle returns while a take-up retracts the thread so as to tighten the stitch.

“This cycle would, for hand work, be immeasurably more complicated and difficult than ordinary sewing, but it consists of operations mechanically easy of performance in swift and accurately timed sequence, and as the whole of the thread in use has no longer to be passed from one side of the fabric to the other as each stitch is made, it has brought with it the all-important advantage of our being able to work with a continuous thread. Here, then, is a magnificent example of ‘coding.’ It is not to be wondered at that the machines which it has given to the world are in well-nigh universal use, and have profoundly modified both our social and industrial economy.”

Obed Hussey and His Mower.

One of the supreme inventions of all time is the mower of Obed Hussey, of Maryland, devised in 1833, and afterward adapted to reaping. In the primitive reaping of tall grain one hand keeps the stalks upright, while the other hand cuts these stalks with a scythe. Hussey, in a masterpiece of “coding,” arrayed metal fingers which keep the grain from bending, while vibrating knives sever the stalks. To this day his invention remains the core of millions of mowers as well as reapers; it has economized labor to an extent beyond estimate, and by shortening the time required in harvesting has saved many million bushels of grain which otherwise would have been destroyed by bad weather.

Not a few inventors of the first mark are found among the men of great ability who unite training in two distinct fields of science, whose alliances they thoughtfully cultivate.

New Modes of Attack.

Thus Helmholtz, at once a physician and a physicist, devised the ophthalmoscope, that simple instrument for observing the interior of the eye. On a plane less lofty an inventor’s success may turn on his width of outlook, his intimacy with fields remote from the home acre, so that he may gainfully ally two arts or processes that, to a casual glance, seem utterly unrelated or unrelatable. When a pneumatic tube between a post-office and a railroad station is obstructed, there would seem to be no promise of aid in a fire-arm. But snapping off its blank cartridge at the open end of the tube gives back an echo through the air within the tube; in measuring the interval between touching the trigger and hearing the echo, there is news as to where the tube is choked, the velocity of sound in air being known. From the labors of a postmaster let us turn to those of an apothecary, who pounds and grinds his drugs in a mortar which has descended from the day when it reduced grain to flour. The grindstones which succeeded the mortar were only in recent years ousted by Hungarian rollers of steel which separate the constituents of grain with a new perfection. Their excellence consists in imitating the crushing of the mortar, not in attempting the grinding of the familiar burrs.

The miller’s practice in one particular has given the postmaster a hint of value. In a flour-mill a cheap and sufficient motor is simple gravity as the products pass from one machine to the next. At the very outset the wheat is taken by conveyors to the top floor, whence its products descend, stage by stage, impelled by gravity alone, until the finished and barreled flour rolls into shipping rooms beside the railroad tracks. This principle has been adopted at the Chicago Post-office, where the mails as received are borne to the top floor, thence, by gravity, they take their way as sorted and re-sorted, to the ground floor where they are finally disposed of.

In a field somewhat parallel is the modern art of designing the layout of a great manufacturing plant so that the material shall travel as little as possible between its entrance and its exit. In a well planned ship-yard the machines are so placed that the steel plates, bars and girders, the planks and boards, move continuously from one machine to its neighbor, ending at last by reaching the building berth.

Shears for metal, cutting scissors-fashion, have long been familiar; the Pittsburg, Fort Wayne and Chicago Railroad employs the Murphy machine, on the same principle, to cut up old ties and bridge timbers intended for fuel. The upper moving blade is set about an inch out of line from the lower fixed blade, so as to allow spikes or bolts to pass through without injuring the machine. In dividing cord wood for stoves and furnaces a machine of this kind might be used instead of a saw.

It is by perfect means of subdivision that new and cheap materials for writing and printing are now produced. The leaves offered by the papyrus to scribes were used for centuries, so that the plant has given its name to paper now made from fibres of cotton, linen, or wood, finely divided, thoroughly mixed, and squeezed between rollers much as if paste. Paper from its smoothness, its absence of grain and its low price, is far preferable to papyrus leaves or vellum. Its manufacture has been copied in diverse new industries. Wood ground to powder, worked into pulp, molded into pails, tubs and the like, is saturated with oil to produce wares of indurated fibre. A pail thus manufactured will not split apart in dry weather when empty, or absorb liquids, and it is as easily kept clean as glass.

While wood has thus found a rival in pulp, stone has a new competitor much more formidable. Pavements and piers are often needed in long stretches, without joints for the admission of rain or frost. The demand is met by cements and concretes easily laid in unjointed miles. These materials when strengthened with skeletons of steel find many uses; a brief survey of them is given in this book. A sister product, terra cotta, baked at high temperatures, is now molded in beautiful designs not only for tiles, but as walls, cornices, finials, vases, hearths, and statuary.

Linotype and Its Use of Wedges.

Clay as tablets was one of the first mediums of the printer’s art, an art of late years exposed to many a surprise from unexpected invaders. Composition is now performed by machines of various models, one of them being Mergenthaler’s linotype, as employed for this book. In effect this machine is a caster rather than a compositor, and recalls the chief tasks of the type-foundry. As an operator touches its keys he releases a succession of matrices, from which is cast a line as a unit. In its latest form this machine enables the operator to change instantly from one font to another, introducing roman, italic, and black face type in the same line at will. Intricate book, tabular and pamphlet matter, with chapter headings, titles, or marginal notes may in this new model be set up at a speed four to six times quicker than hand composition.

An illustration shows the two-letter matrices of a special Mergenthaler machine. The upper is usually a body character and the lower an italic, a small capital or a black face. These lower matrices are lifted a little by a key so as to come in line with upper matrices. In this way the compositor has at command two distinct fonts. Groove E receives the ears of the matrices. In a normal position D receives the ears of the matrices elevated to produce the secondary characters. In this way the matrices are held in position as casting proceeds. Five double-wedge justifiers will be observed between the matrices. These devices, invented by J. W. Schuckers, form an essential part of the machine. Justification, let the reader be reminded, is so spacing the contents of a line that it shall neatly end with a word or syllable. In typewritten manuscript the lack of justification leaves the ends of lines jagged and unsightly. Mr. Schuckers at the end of every word places a pair of wedges. When the operator is close to the end of a line he pushes in the whole row of wedges in that line; the outer sides of each pair remain always parallel, and as pushed in these outer sides are just sufficiently forced apart to space out the line with exactitude. To lift a table or a desk, and at the same time keep it always level, we may use pairs of wedges in the same manner; they must, of course, be much larger and thicker than those used in linotypy. See next page for an illustration.

To-day a book may be reproduced without any recourse whatever to the type long indispensable. A photographer takes the volume, and repeats it in pages of any size we wish, dispensing not only with the type-setter or the type-caster, but even with the proofreader, since a camera furnishes an exact fac-simile of the original work. If the book is illustrated, a further economy is enjoyed; its pictures are copied as faithfully and cheaply as the letterpress.

Ingenuity in Copying and Decorating.

A feat which is a mere trifle as compared with reproducing a book by photography, turns upon a loan from an old resource. Confectioners from time immemorial have squeezed paste out of bags through apertures into ornaments for wedding cakes and the like. With similar bags decorators force a thin stream of plaster into a semblance of flowers, fruits, and arabesques on their ceilings and cornices. On the same plan, with pressure more severe, soap is forced, from a tank through a square opening to form bars for the laundress. Increasing the pressure once again, clay for bricks is urged forth, to be divided into lengths suitable for the kiln. Lead pipe is manufactured on the same principle, recalling the production of macaroni. A further step was taken by Alexander Dick, the inventor of Delta metal; by employing hydraulic pressure on metals at red heat he poured out wires and bars of varied cross-sections, superseding the method of drawing through dies.

Frost as a Servant.

Cold as well as heat may be employed in a novel manner. The flesh of birds, beasts, and insects is now frozen hard, so as to be sliced into extremely thin sections clearly showing the details of structure. How a freezing process may aid the miner was shown first in Germany in 1880, when Hermann Poetsch, a mining engineer, had to sink a shaft near Aschersleben, to a vein of coal, where, after excavating 100 feet, a stratum of sand eighteen feet thick, overlying the coal, was encountered. It occurred to Poetsch that the great difficulty occasioned by the influx of water through the sand could be overcome by solidifying the entire mass by freezing. To do this, he penetrated the sand to be excavated with large pipes eight inches in diameter, sunk entirely through it and a foot or two into the underlying coal. These were placed in a circle at intervals of a metre, and close to the periphery of the shaft. They were closed at the lower end. Inside each of these and open at its lower end was a pipe an inch in diameter. This system of pipes was so connected that a closed circulation could be produced down through the small pipes and up through the large ones. An ice-machine, such as brewers use, was set up near by and kept at a temperature below zero Fahrenheit. A tank filled with a solution of chloride of magnesium, which freezes at -40° Fahr., had its contents circulated through the ground pipes described. Thermometers placed in pipes sunk in the mass of sand showed 51.8° Fahr. at the beginning of the process. The circulation was kept up and on the third day the whole mass was frozen. Within the continuous frozen wall the material was excavated without damage from caving in or inflow of water. The freezing entered the coal three feet, and to a distance six feet outside the pipes. The circulation was kept up until the excavation and walling were complete. On a somewhat similar plan tunnels have been bored through difficult ground. Of late years at Detroit, and elsewhere, serious breaks in water-mains have been repaired after a freezing process has solidified the stream.

Polarized Light and X-Rays.

Light, as well as heat and cold, is to-day bidden to perform new duties. It was long ago observed that polarized light as it takes its way through transparent crystal or glass clearly reveals in areas of variegation, any strains to which the crystal or glass may be subjected. Of late this fact has been applied with new skill to investigating strains in engineering structures. A model in glass, carefully annealed, is placed in the path of a beam of polarized light. By shifting the points of application and of support, by loading the structure more or less, and here or there, the distribution of stresses and strains is directly shown to the eye. In this way curved shapes of various kinds have been investigated, as well as bodies in which Hooke’s law of the strict proportionality of strain to stress does not apply. Photographs taken by this method show the distribution of stresses in rings subjected to external compression, crank shafts, and car-coupler hooks. It would be interesting thus to compare standard types of girders, trusses, and bridges, as well as arches of various forms, both regular and skew.

Polarized light, which when first discovered seemed nothing more than a singular and quite sterile phenomenon, has other uses of great importance. It tells the chemist how much sugar a given solution contains; it displays the inner architecture of rocks when these are sawn into thin sections.

Even more valuable than polarized light are the X-rays discovered by Professor Röntgen. One of their latest uses is to reveal impurities and air bubbles in electric cables, affording a procedure much simpler and easier than to employ electrical instruments. In the production of X-rays and similar rays a tube as nearly vacuous as possible is employed. As an aid in removing air Professor James Dewar, of Cambridge University, has recently adopted cocoanut charcoal with remarkable success. He subjects it to the intense cold of liquid air, then establishing communication between a receptacle filled with this charcoal and a bulb exhausted to one fourth of the ordinary atmospheric pressure, he has air so tenuous that an electric spark passes through it with difficulty. So much for developing the long known affinity of charcoal for gases, a property which increases in degree as temperatures fall.

CHAPTER XXII
AUTOMATICITY AND INITIATION

Self-acting devices abridge labor . . . Trigger effects in the laboratory, the studio, and the workshop . . . Automatic telephones . . . Equilibrium of the atmosphere may be easily upset.

At this place we may for a little while consider a few fundamental principles of construction whereby inventors have economized material, labor and energy by making their devices self-acting, and by so poising a contrivance that a mere touch at the right time and place sets it going.

Steam Engines.

Humphrey Potter was a boy whose duty obliged him to open and shut the valves of a Newcomen steam-engine as it slowly went its rounds. He was a human sort of boy, who liked play better than his irksome task, so he found a way to rid himself of the drudgery of constantly moving his valve-handles to and fro. He tied a rod to the walking beam in such wise that it opened the valve at the proper moment, and, at another point in its circuit, when necessary, closed it. Then and only then did the steam-engine become self-acting. In the best modern types of engine this automaticity goes far indeed. Not only does the mechanism pump water as required into both the boiler and the condenser, it shuts off steam instantly when the engine moves too swiftly, and, when the engine speed is sluggish the port betwixt boiler and cylinders is opened to the full. And further: automatic stokers bear coal into the furnace at a rate which varies with the demand, should the steam pressure fall through an undue call for power, then an extra quantity of coal is borne upon the grate-bars. When oil is the fuel automatic stoking is, of course, at its best, there being neither cinders nor ashes to be removed—a duty, by the way, which in large central stations requires extensive machinery, all automatic.

Self-winding Clocks.

The essence of automaticity is that mechanism at a certain, predetermined point in an operation shall perform a required act. Thus, to take the common example of a striking clock: at the end of each hour a detent is pulled so as to release a hammer which hits a gong the proper number of times. Let us suppose the clock to be driven by a weight or a spring in the ordinary way; every day or every week the weight or spring will require to be wound up. In time-pieces of a new variety the period during which no attention whatever is needed is lengthened to a year. The Self-winding Clock Company, of Brooklyn, New York, makes a clock which is driven by a fine spring, much like a common clock; that spring every hour is automatically wound up by a tiny electric motor connected with a small battery in the clock case. An attachment is provided by which, through the wires of the Western Union Telegraph Company, the clock is every hour regulated to the standard time of the National Observatory at Washington. The charge for this service is one dollar a month.

Looms and Presses.

To-day a designer always seeks to make a machine self-acting, to limit the operator’s task to starting, directing, and stopping, all with the utmost facility and the least possible exertion. So far has success gone in this direction that a single tender in a cotton-mill may have charge of sixteen Northrop looms, and go to dinner leaving all at work. In case that a thread breaks in any of them, the loom will stop of itself and no harm will be done, the only loss consisting in the time during which the wheels and levers have lain idle. A stop-motion at its simplest is a fork through which the thread travels; as the thread moves forward, the fork is bent downward extending a light coiled spring; should the thread break, the spring instantly lifts the fork, which in rising stops the machine.

Among the most noteworthy automatic machines are the presses which take a continuous roll of paper, print both sides, cut it into leaves, fold these, paste them at the back, and, if desired, sew them together and attach a cover. Such a press stands for the union of several operations once distinct; it argues great ingenuity, careful planning, with paper exactly adapted to the stresses it must encounter, while the ink is of a quick-drying variety.

The Dexter Feeding Mechanism.

Binding operations and a good deal of printing have to deal with separate sheets of paper or card. To feed these to presses, folders or binders was for many years a task for the hand. To-day the Dexter Folder Company, of New York, in a diversity of machines supersedes this toil by an ingenious imitation of manual movements. The uppermost sheet of paper in a pile is for a moment held down at A by a rubber finger, during that moment a small rubber roller B slightly buckles the sheet; at the same time an airblast lifts the sheet from its pile; that done, all in a twinkling, finger A rises and the sheet passes either into a press or a folding machine. So nicely limited is the pathway for the paper that no more than one sheet can pass at a time; if two or more sheets present themselves, the feeding mechanism stops, bringing the press or folder to a standstill. As each sheet passes from under the rubber fingers, the table bearing the pile of paper is lifted by just one thickness of paper.

Self-Acting Appliances in Metallurgy.

Mr. James Douglas, president of the Copper Queen Company, New York, thus describes automatic devices in metallurgy: “The gold mill, with its series of automatic operations, is the offspring of Californian ingenuity. In it manual labor is almost entirely replaced by ocular labor, for superintendence and not work is the function of the mill-hands. The ore, dumped into the breakers, falls into large pockets, whence it slides into automatic feeders, which supply the stamps with regulated quantities. The free gold is partly extracted by liquid mercury in the mortars, and by copper plates attached to their sides, and partly on an apron of amalgamated copper plates, over which crushed pulp flows as it issues from the battery screen. Automatic vanners receive the tailings, separate the sulphurets, and discharge the waste. When the power is water, the stream is divided to Pelton wheels, coupled to the separate groups or even pieces of machinery. The absence of intermediate running gear increases not only the sense, but the reality of automaticity, and makes a skilfully arranged and thoroughly equipped Californian mill one of the triumphs of modern mechanical metallurgy.”

Directive Paths.

An interesting field of ingenuity concerns itself with giving work the right start and a simple path. A tear in a sheet of paper accurately follows the line of a directive crease. Postage stamps, small as they are, we readily detach from one another because perforations give direction to the tearing strain. So the quarryman takes care to cut a V-shaped groove in the rock he is to break, along which groove the break takes its way. A bolt when over-strained will break in the thread, whether this be the smallest section or not, because the thread is a starting point for a parting. A rod of glass is divided with a slight jar, provided that a groove has been filed in its surface. In all this there is shown the importance of avoiding in a casting, or forging, such minute cracks as under severe strain may lead to rupture.

The Pianola.

Within the past ten years automatic musical instruments have been much improved and are now well established in public favor. Not a few teachers of mark use them in their schools as a means of familiarizing their pupils with the best music. All these instruments afford an opportunity for expression on a performer’s part; the effects producible by a practiced performer are remarkable, and give color to the prediction that automatic music may have a parallel history with that of the photograph, which has at last attained a truth and beauty which bring it to a rivalry with the art of the painter.

From the educational series issued by the Æolian Company, New York, a few notes from Schumann’s “Traumerei” are here given, together with these notes as they appear on a music roll for the Pianola.

A Pianola is operated by suction, through the exhaustion of air from a bellows normally distended by springs as shown in 5 in the accompanying illustration. The exhauster is operated by the pedal 1; the board 3, with its small bellows, exhausts the air from 5 in the chest 7 by a series of valves not shown in detail. When the air is pumped from 5 by the motion of exhauster 3, this bellows collapses notwithstanding the retractile spring 6. The exhaust condition may now operate upon any chamber of the whole mechanism through trunk 7 and pipe 8. When a perforation in a music sheet 16 passes over its corresponding duct in tracker 15, air is admitted through tube 14, which relieves the diaphragm in chamber 9, made of a very thin piece of leather, upon which rests the stem of valve 11. Owing to the suction in chamber 9 this diaphragm instantly raises and shuts the outer port 23 by means of valve 11, giving a free communication from pipe 8 through chambers 9 and 12, to the striking pneumatic 13 which collapses, and through pitman 19 and finger 20 strikes the key. As soon as the unperforated part of the music sheet has passed over the hole 15 in the trackerboard, the flow of air through pipe 14 is cut off and the pressure on the small diaphragm in chamber 9 has ceased to be operative, and valve 11 immediately drops and allows air to pass into striking pneumatic 13, through port 23, so that pneumatic 13 and the key levers come back to their normal positions.

Automatic Telephones.

Much self-acting machinery employs electricity. By virtue of this wonderful agent the Automatic Electric Company of Chicago instals telephonic systems which enable a subscriber to connect himself directly with any other subscriber, without the intervention of an operator at the central station. As exemplified in large exchanges such as those of Dayton, Ohio, and Grand Rapids, Michigan, the apparatus is complex in its detail. If we take a small exchange, such as that of a village with 100 instruments, we may readily understand the main principles of the method. Let us suppose that No. 1 of our instruments is at the Post Office, where the Postmaster wishes to call 58. With a finger he moves hole 5 in the dial plate of his calling instrument (see the page opposite 336) until it touches a protruding stud. Then he lets go, when the dial returns to its original position. In returning it sends five impulses to the central office where a vertical rod is lifted five notches (see illustration, page 336.) He next moves hole 8 to the stud and lets go. This time the rod turns through a considerable part of its semicircle of motion. The instant its journey is at an end a tiny metallic arm flies out and connection is completed with a wire running to 58, ringing his bell. In case he is busy, a buzzing noise will be heard in telephone No. 1. The switch mechanism which comes into play in all this is simple. There are ten rows of switches, ten in each row: the lowest row runs from 1 to 10, the next from 11 to 20, and so on. The upward motion of the vertical rod in our example brought it to the fifties; the turning motion decided that out of these fifties switch 58 should be connected with No. 1. When a conversation ends, hanging up the receiver sends a current over both wires of the circuit so as to release the selector rod, which returns to its original position.

If instead of a village we have a fairly large town, with an exchange of 1000 subscribers, a call for let us say 829 will involve taking to the stud first hole 8, then hole 2, and lastly hole 9. And so on for exchanges still larger. The pioneer inventor in automatic telephony was the late Mr. Almon B. Strowger.

Chemical Triggers.

From triggers electrical we now pass to triggers chemical. A gun may be charged with powder and remain for years perfectly at rest until a touch on the trigger explodes the powder with tremendous effect. The example is typical: nature and art abound with cases where a little energy, rightly directed, controls energy vastly, perhaps infinitely, greater in quantity. Often in a chemical compound the poise of attraction is so delicate that it may be disturbed by a breath, or by a note from a fiddle, as when either of these induces iodide of nitrogen to explode. A beam of light works the same result with a mixture of chlorine and hydrogen. One of the most familiar facts of chemistry is that a fuel, such as coal, may remain intact in air for ages. Once let a fragment of it be brought to flaming heat and all the rest of the mass will take fire too. Iron has a strong affinity for oxygen, but for union there must be at the beginning some moisture with the gas; the same is true of carbon. A burning jet of carbon monoxide may be extinguished by plunging it into a jar of dried oxygen. Gases from the throat of a blast furnace, at a temperature of 250° to 300° Centigrade, are not inflammable in the atmosphere until the air is moistened by steam or otherwise. Then in a flash combustion begins in earnest.

In photography we meet with similar facts: violet rays may begin an impression which yellow light can finish and finish only. Vulcanite is transparent to red and infra-red rays which, although without action upon an unexposed plate, are capable of continuing the action of actinic rays upon a plate which has been exposed for a very short time.

Why Weather is Uncertain.

From photography let us pass to a glance at the atmospheric conditions which greatly affect its work. The weather from day to day depends upon factors so variable and unstable that prediction beyond twenty-four hours is unsafe. “Suppose a stratum of air,” says Professor Balfour Stewart, “to be very nearly saturated with aqueous vapor; that is to say, to be just a little above the dew-point; while at the same time it is losing heat but slowly, so that if left to itself it would be a long time before moisture were deposited. Now such a stratum is in a very delicate state of molecular equilibrium, and the dropping into it of a small crystal of snow would at once cause a remarkable change. The snow would cool the air around it, and thus moisture would be deposited around the snowflake in the form of fine mist or dew. Now, this deposited mist or dew, being a liquid, and giving out all the rays of heat possible to its temperature, would send its heat into empty space much more rapidly than the saturated air; therefore it would become colder than the air around it. Thus more air would be cooled, and more mist or dew deposited; and so on until a complete change of condition should be brought about. In this imaginary case the tiniest possible flake of snow has pulled the trigger, as it were, and made the gun go off,—has altered completely the whole arrangement that might have gone on for some time longer as it was, had it not been for the advent of the snowflake. We thus see how in our atmosphere the presence of a condensable liquid adds an element of violence, and also of abruptness, amounting to incalculability, to the motions which take place. This means that our knowledge of meteorological phenomena can never be mathematically complete, like our knowledge of planetary motions, inasmuch as there exists an element of instability, and therefore of incalculability, in virtue of which a very considerable change may result from a very small cause.”

In view of the inherent difficulties it is certainly creditable that the predictions of the United States Weather Bureau should prove true six times in seven, greatly inuring to the safety of mariners, of passengers by lake and sea, and to the saving of crops under threat of destruction by storms.

CHAPTER XXIII
SIMPLIFICATION

Simplicity always desirable, except when it costs too much . . . Taking direct instead of roundabout paths. . . . Omissions may be gainful . . . Classification and signaling simpler than ever before.

For a simple task the inventor’s means should be as simple as possible. Mr. J. J. Thomas in his “Farm Implements” says:—

Simplicity of Build Desirable.

“After a trial of a multitude of implements and machines, we fall back on those of the most simple form, other things being equal. The crow-bar has been employed from time immemorial, and it will not likely go out of use in our day. For simplicity nothing exceeds it. Spades, hoes, forks are of similar character. The plow, though made up of parts, becomes a single thing when all are bolted and screwed together. For this reason, with its moderate weight, it moves through the soil with little difficulty—turning aside for obstructions, on account of its wedge form, when it cannot remove them. The harrow, although composed of many pieces, becomes a fixed, solid frame, moving on through the soil as a single piece. So with simpler cultivators. Contrast these with Pratt’s ditching machine considerably used some years ago, but ending in failure. It was ingeniously constructed and well made, and when new and every part uninjured, worked admirably in some soils. But it was made up of many parts and weighed nearly half a ton. These two facts fixed its doom. A complex machine of this weight moving three to five feet per second, could not strike a large stone without a formidable jar, and continued repetitions of such blows bent and deranged the working parts. After using a while, these bent portions retarded its working; it must be frequently stopped, the horses becoming badly fatigued, and all the machines were finally thrown aside. This is a single example of what must always occur with the use of heavy complex machinery working in the soil. Mowing and reaping machines may seem to be exceptions. But they do not work in the soil, or among stones; but operate on the soft, slightly resisting stems of plants. Every farmer knows what becomes of them when they are repeatedly driven against obstructions by careless teamsters.”

Simplification Has Limits.

In discussing form we saw that simple shapes, such as those of sticks cut from a cylindrical tree, are not so strong as the less simple forms of hollow cylinders. We found that a joist, of plain rectangular section, is not so good a burdenbearer as a girder whose section resembles the letter I. If a slide for a timber is to be built on a mountain side, a novice would suppose that a straight inclined plane would afford the speediest path for the descending wood. Not so. More speedy is a slide contoured as a cycloid, the curve traced by a pencil fastened to the rim of a wheel as the wheel rolls along a floor beside a wall against which the pencil presses.

Not all tasks are simple, so that it is often best to build and use a machine as complicated as a turret-lathe or a Jacquard loom. Whatever the inventor seeks first, last and all the time is Economy; to that end he adopts whatever means will serve him best, whether simple or not. Professor A. B. W. Kennedy, famous as a teacher of machine design, says:—

“Simplicity does not mean fewness of parts. Reuleaux showed long ago that with machines there was in every case a practical minimum number of parts, any reduction below which was accompanied by serious practical drawbacks. Nor is real simplicity incompatible with considerable apparent complexity. The purposes of machines being continually more complex, simplicity must not be looked upon as absolute, but only in its relation to a particular purpose. There are many very complex-looking pieces of apparatus which work so directly along each of their main branch lines that they are in reality simple. It is usual that the first attempt to carry out a new purpose results in a very complicated machine. It is only by the closest examination of the problem, the getting at its very essence, that the machine can be simplified. If a problem is only soluble by extremely complicated apparatus, it becomes a question whether it is worth having. Closely allied to simplicity is Directness. Certain transformations are unavoidable, but the fewer the better. In some cases they may be as indispensable as the abused middleman in matters economic. In the first machine to do something mechanically hitherto done by hand, the error is often made of trying to imitate hand-work rigorously. The first sewing-machine was, I believe, made to stitch in the same way as a seamstress. It was not until a form of stitch suitable for a machine, although unsuitable for the hand, was devised, that the sewing-machine was successful. The first railroad carriages were practically stage-coaches put on trucks, from which the present carriages have only very slowly been evolved.”

Directness.

A few years ago it was usual to attach pumps, dynamos, and other machinery to their actuating engines by pulleys and belts. To-day in most cases the connection is direct; all the energy which would be absorbed by intervening wheels and leather is saved. In steam-turbines one and the same shaft carries the steam-vanes and the armature of an electrical generator. In saw-mills of modern design a very long steam cylinder is provided with a piston directly attached to the saw carriage. The same principle gives high economy to the steam hammer and pile-driver of Nasmyth. Hammers, drills, cutters and other tools driven by compressed air are directly attached to the rod which holds the piston. In like manner Saunders’ channeling machine, actuated by steam, has its cutters attached to its piston, so that a blow is dealt with no intervening crank-shaft, lever or spring.

Direct, too, is the binding machine for magazines and cheap books, which simply stitches with wire the whole together at the back, as if so many thicknesses of cloth. With the same immediacy we have wall-papers printed directly from the oak or maple they are to represent. Indeed, veneers are now so cheap and good as to be used instead of paper as wall coverings. In the province of art Mr. Hubert Herkomer has accomplished a notable feat in the way of directness, dispensing with the camera, or any of the etcher’s preliminaries of biting or rocking. He paints in monochrome on a copper plate as he would on a panel or canvas, covers his painting with fine bronze powder to harden the surface, from which he then takes an electrotype.

A supreme feat of directness was the invention of a machine which relates itself to art, science and business, the phonograph. Forty years ago Faber constructed a talking machine of bellows to imitate the lungs, with an artificial throat, larynx, and lips affording a weird and faulty imitation of the voice. Edison, bidding sound-waves impress themselves directly on a plastic cylinder, reproduces human tones and other sounds with vastly better effect. Faber sought to copy the method of voice production. Edison set himself the task of taking tones as produced and making them impress a surface from which they can be repeated at will.

Contrivances Which Pay a Double Debt.

A lamp commonly used by camping parties, and well worthy of wider employment, is at once a source of heat and light; while it boils a kettle it sheds an ample beam upon one’s table or book. Just this union of two services may be found in the crude lamp of the Eskimo.

Many processes of manufacture once separate are now united with economy of time and power. Steam cylinders for mangling, ironing and surfacing paper, effect smoothing and drying at one operation. Green lumber for making furniture is bent and seasoned at the same time. Wire is tempered as drawn. At first reflectors were distinct from lamps; in an excellent form of incandescent bulb the upper part of the container is silvered, increasing the efficiency of reflection in decided measure, as shown on page 75.

Ascertaining Solid Contents.

Sometimes an indirect path is better than a direct course; or, as the sailors say: “The longest way round is the shortest way there.” We can readily measure the contents of solids which are regular or fairly regular of outline. It is easy to compute or estimate the contents of a stone as hewn by a mason to form part of a wall, but to find the volume of a rough boulder by direct measurement is too difficult a task to be worth while. Let us have recourse, then, to an indirect plan which goes back to Archimedes: it will remind us of how the casting process evades the toil of chipping or hammering a mass of metal into a desired form. We take a vessel of regular shape, preferably a cylinder, duly graduated, and partly fill it with water. Any solid, however irregular, immersed therein, will at once have its contents declared by the height to which the water rises in its container, the water-levels before and after the immersion being compared. Incidentally we here have a means of ascertaining specific gravities. Weigh this body before and during immersion; comparison of the two quantities will tell the specific gravity of the body, that is its density as compared with that of water. For example a mass of iron which in air weighs 7.75 pounds will in water weigh 6.75 pounds, so that the specific gravity of iron is 7.75, the difference between the two weights being unity.

Sometimes we wish to know the solid contents of a body which will not bear immersion in water; a mass of gum, for instance. In such a case we immerse the body in a graduated vessel filled with fine dry sand, carefully sifted free of hollow spaces. Both before and after immersion the sand is brought to a level which is carefully noted. The difference between these levels, measured in the graduations of the container, gives the solid contents of the immersed body.

Measuring Refraction.

The degree in which a crystal, or a particular kind of glass, bends a beam of light is usually measured by giving the crystal or glass the form of a prism, through which rays are sent. Sometimes a crystal is so small and irregular that this method is not feasible. Then the inquirer resorts to an indirect plan. He immerses the crystal in liquids which he mixes until the crystal disappears through ceasing to bend light differently from the surrounding bath. He then fills a hollow glass prism with this liquid, and in noting its refraction he learns that of the immersed crystal.