Simon Lake set to work to invent a way by which a wrecked vessel or a precious cargo could be got at from below the surface. Though the waves may be tossing their whitecaps high in air and the strong wind may turn the watery plain into rolling hills of angry seas, the water twenty or thirty feet below hardly feels any surface motion. So he set to work to build a vessel that should be able to sail on the surface or travel on the bottom, and provide a shelter from which divers could go at will, undisturbed by the most tempestuous sea. People laughed at his idea, and so he found great difficulty in getting enough capital to carry out his plan, and his first boat, built largely with his own hands, had little in its appearance to inspire confidence in his scheme. Built of wood, fourteen feet long and five feet deep, fitted with three wheels, Argonaut Junior looked not unlike a large go-cart such as boys make out of a soap-box and a set of wooden wheels. The boat, however, made actual trips, navigated by its inventor, proving that his plan was feasible. Argonaut Junior, having served its purpose, was abandoned, and now lies neglected on one of the beaches of New York Bay.

The Argonaut, Mr. Lake's second vessel, had the regular submarine look, except that she was equipped with two great, rough tread-wheels forward, and to the underside of her rudder was pivoted another. She was really an under-water tricycle, a diving-bell, a wrecking-craft, and a surface gasoline-boat all rolled into one. When floating on the surface she looked not unlike an ordinary sailing craft; two long spars, each about thirty feet above the deck, forming the letter A—these were the pipes that admitted fresh air and discharged the burnt gases of the gasoline motor and the vitiated air that had been breathed. A low deck gave a ship-shape appearance when floating, but below she was shaped like a very fat cigar. Under the deck and outside of the hull proper were placed her gasoline tanks, safe from any possible danger of ignition from the interior. From her nose protruded a spar that looked like a bowsprit but which was in reality a derrick; below the derrick-boom were several glazed openings that resembled eyes and a mouth: these were the lookout windows for the under-water observer and the submarine searchlight.

The Argonaut was built to run on the surface or on the bottom; she was not designed to navigate half-way between. When in search of a wreck or made ready for a cruise along the bottom, the trap door or hatch in her turret-like pilot house was tightly closed; the water was let into her ballast tanks, and two heavy weights to which were attached strong cables that could be wound or unwound from the inside were lowered from their recesses in the fore and after part of the keel of the boat to the bottom; then the motor was started connected to the winding mechanism, and, the buoyancy of the boat being greatly reduced, she was drawn to the bottom by the winding of the anchor cables. As she sank, more and more water was taken into her tanks until she weighed slightly more than the water she displaced. When her wheels rested on the bottom her anchor-weights were pulled completely into their wells, so that they would not interfere with her movements.

Then the strange submarine vehicle began her voyage on the bottom of the bay or ocean. Since the pipes projected above the surface plenty of fresh air was admitted, and it was quite as easy to run the gasoline engine under water as on the surface. In the turrets, as far removed as possible from the magnetic influences of the steel hull, the compass was placed, and an ingeniously arranged mirror reflected its readings down below where the steersman could see it conveniently. Aft of the steering-wheel was the gasoline motor, connected with the propeller-shaft and also with the driving-wheels; it was so arranged that either could be thrown out of gear or both operated at once. She was equipped with depth-gauges showing the distance below the surface, and another device showing the trim of the vessel; compressed-air tanks, propelling and pumping machinery, an air-compressor and dynamo which supplied the current to light the ship and also for the searchlight which illuminated the under-water pathway—all this apparatus left but little room in the hold, but it was all so carefully planned that not an inch was wasted, and space was still left for her crew of three or four to work, eat, and even sleep, below the waves.

Forward of the main space of the boat were the diving and lookout compartments, which really were the most important parts of the boat, as far as her wrecking ability was concerned. By means of a trap door in the diving compartment through the bottom of the boat a man fitted with a diving-suit could go out and explore a wreck or examine the bottom almost as easily as a man goes out of his front door to call for an "extra." It will be thought at once, "But the water will rush in when the trap door is opened." This is prevented by filling the diving compartment, which is separated from the main part of the ship by steel walls, with compressed air of sufficient pressure to keep the water from coming in—that is, the pressure of water from without equals the pressure of air from within and neither element can pass into the other's domain.

An air-lock separates the diver's section from the main hold so that it is possible to pass from one to the other while the entrance to the sea is still open. A person entering the lock from the large room first closes the door between and then gradually admits the compressed air until the pressure is the same as in the diving compartment, when the door into it may be safely opened. When returning, this operation is simply reversed. The lookout stands forward of the diver's space. When the Argonaut rolls along the bottom, round openings protected with heavy glass permit the lookout to follow the beam of light thrown by the searchlight and see dimly any sizable obstruction. When the diving compartment is in use the man on lookout duty uses a portable telephone to tell his shipmates in the main room what is happening out in the wet, and by the same means the reports of the diver can be communicated without opening the air-lock.

This little ship (thirty-six feet long) has done wonderful things. She has cruised over the bottom of Chesapeake Bay, New York Bay, Hampton Roads, and the Atlantic Ocean, her driving-wheels propelling her when the bottom was hard, and her screw when the oozy condition of the submarine road made her spiked wheels useless except to steer with. Her passengers have been able to examine the bottom under twenty feet of water (without wetting their feet), through the trap door, with the aid of an electric light let down into the clear depths. Telephone messages have been sent from the bottom of Baltimore Harbour to the top of the New York World building, telling of the conditions there in contrast to the New York editor's aerial perch. Cables have been picked up and examined without dredging—a hook lowered through the trap door being all that was necessary. Wrecks have been examined and valuables recovered.



Although the Argonaut travelled over 2,000 miles under water and on the surface, propelled by her own power, her inventor was not satisfied with her. He cut her in two, therefore, and added a section to her, making her sixty-six feet long; this allowed more comfortable quarters for her crew, space for larger engines, compressors, etc.

It was off Bridgeport, Connecticut, that the new Argonaut did her first practical wrecking. A barge loaded with coal had sunk in a gale and could not be located with the ordinary means. The Argonaut, however, with the aid of a device called the "wreck-detector," also invented by Mr. Lake, speedily found it, sank near it, and also submerged a new kind of freight-boat built for the purpose by the inventor. A diver quickly explored the hulk, opened the hatches of the freight-boat, which was cigar-shaped like the Argonaut and supplied with wheels so it could be drawn over the bottom, and placed the suction-tube in position. Seven minutes later eight tons of coal had been transferred from the wreck to the submarine freight-boat. The hatches were then closed and compressed air admitted, forcing out the water, and five minutes later the freight-boat was floating on the surface with eight tons of coal from a wreck which could not even be located by the ordinary means.

It is possible that in the future these modern "argonauts" will be seeking the golden fleeces of the sea in wrecks, in golden sands like the beaches of Nome, and that these amphibious boats will be ready along all the dangerous coasts to rush to the rescue of noble ships and wrest them from the clutches of the cruel sea.

Mr. Lake has also designed and built a submarine torpedo-boat that will travel on the surface, under the waves, or on the bottom; provided with both gasoline and electric power, and, fitted with torpedo discharge tubes, she will be able to throw a submarine torpedo; her diver could attach a charge of dynamite to the keel of an anchored warship, or she could do great damage by hooking up cables through her diver's trap door and cutting them, and by setting adrift anchored torpedoes and submarine mines.

Thus have Jules Verne's imaginings come true, and the dream Nautilus, whose adventures so many of us have breathlessly followed, has been succeeded by actual "Hollands" and practical "Argonauts" designed by American inventors and manned by American crews.



LONG-DISTANCE TELEPHONY

What Happens When You Talk into a Telephone Receiver

In Omaha, Nebraska, half-way across the continent and about forty hours from Boston by fast train, a man sits comfortably in his office chair and, with no more exertion than is required to lift a portable receiver off his desk, talks every day to his representative in the chief New England city. The man in Boston hears his chief's voice and can recognise the peculiarities in it just as if he stood in the same room with him. The man in Nebraska, speaking in an ordinary conversational tone, can be heard perfectly well in Boston, 1,400 miles away.

This is the longest talk on record—that is, it is the longest continuous telephone line in steady and constant use, though the human voice has been carried even greater distances with the aid of this wonderful instrument.

The telephone is so common that no one stops to consider the wonder of it, and not one person in a hundred can tell how it works.

At this time, when the telephone is as necessary as pen and ink, it is hard to realise a time when men could not speak to one another from a distance, yet a little more than a quarter of a century ago the genius who invented it first conceived the great idea.

Sometimes an inventor is a prophet: he sees in advance how his idea, perfected and in universal use, will change things, establish new manners and customs, new laws and new methods. Alexander Graham Bell was one of these prophetic inventors—the telephone was his invention, not his discovery. He first got the idea and then sought a way to make it practical. If you put yourself in his place, forget what has been accomplished, and put out of mind how the voice is transmitted from place to place by the slender wire, it would be impossible even then to realise how much in the dark Professor Bell was in 1874.

The human speaking voice is full of changes; unlike the notes from a musical instrument, there is no uniformity in it; the rise and fall of inflection, the varying sound of the vowels and consonants, the combinations of words and syllables—each produces a different vibration and different tone. To devise an instrument that would receive all these varying tones and inflections and change them into some other form of energy so that they could be passed over a wire, and then change them back to their original form, reproducing each sound and every peculiarity of the voice of the speaker in the ear of the hearer, was the task that Professor Bell set for himself. Just as you would sit down to add up a big column of figures, knowing that sooner or later you would get the correct answer, so he set himself to work out this problem in invention. The result of his study and determination is the telephones we use to-day. Many improvements have been invented by other men—Berliner, Edison, Blake, and others—but the idea and the working out of the principle is due to Professor Bell.



Every telephone receiver and transmitter has a mouth-and ear-piece to receive or throw out the sound, a thin round sheet of lacquered metal—called a diaphragm, and an electromagnet; together they reproduce human speech. An electric current from a battery or from the central station flows continuously through the wires wound round the electromagnet in receiving and transmitting instruments, so when you speak into the black mouthpiece of the wall or desk receiver the vibrations strike against the thin sheet-iron diaphragm at the small end of the mouthpiece; the sound waves of the voice make it vibrate to a greater or less degree; the diaphragm is placed so that the core of the electromagnet is close to it, and as it vibrates the iron in it produces undulations (by induction) in the current which is flowing through the wires wound round the soft iron centre of the magnet. The wires of the coil are connected with the lines that go to the receiving telephone, so that this undulating current, coiling round the core of the magnet in the receiver, attracts and repels the iron of the diaphragm in it, and it vibrates just as the transmitter diaphragm did when spoken into; the undulating current is translated by it into words and sentences that have all the peculiarities of the original. And so when speaking into a telephone your voice is converted into undulations or waves in an electric current conveyed with incredible swiftness to the receiving instrument, and these are translated back into the vibrations that produce speech. This is really what takes place when you talk over a toy telephone made by a string stretched between the two tin mouth-pieces held at opposite sides of the room, with the difference that in the telephone the vibrations are carried electrically, while the toy carries them mechanically and not nearly so perfectly.

For once the world realised immediately the importance of a revolutionising invention, and telephone stations soon began to be established in the large cities. Quicker than the telegraph, for there was no need of an operator to translate the message, and more accurate, for if spoken clearly the words could be as clearly understood, the telephone service spread rapidly. Lines stretched farther and farther out from the central stations in the cities as improvements were invented, until the outlying wires of one town reached the outstretched lines of another, and then communication between town and town was established. Then two distant cities talked to each other through an intermediate town, and long-distance telephony was established. To-day special lines are built to carry long-distance messages from one great city to another, and these direct lines are used entirely except when storms break through or the rush of business makes the roundabout route through intermediate cities necessary.

As the nerves reaching from your finger-tips, from your ears, your eyes, and every portion of your body come to a focus in your brain and carry information to it about the things you taste, see, hear, feel, and smell, so the wires of a telephone system come together at the central station. And as it is necessary for your right hand to communicate with your left through your brain, so it is necessary for one telephone subscriber to connect through the central station with another subscriber.

The telephone has become a necessity of modern life, so that if through some means all the systems were destroyed business would be, for a time at least, paralysed. It is the perfection of the devices for connecting one subscriber with another, and for despatching the vast number of messages and calls at "central," that make modern telephony possible.

To handle the great number of spoken messages that are sent over the telephone wires of a great city it is necessary to divide the territory into districts, which vary in size according to the number of subscribers in them. Where the telephones are thickly installed the districts are smaller than in sections that are more sparsely settled.

Then all the telephone wires of a certain district converge at a central station, and each pair of wires is connected with its own particular switch at the switchboard of the station. That is simple enough; but when you come to consider that every subscriber must be so connected that he can be put into communication with every other subscriber, not only in his own section but also with every subscriber throughout the city, it will be seen that the switchboard at central is as marvellous as it is complicated. Some of the busy stations in New York have to take care of 6,000 or more subscribers and 10,000 telephone instruments, while the city proper is criss-crossed with more than 60,000 lines bearing messages from more than 100,000 "'phones." Just think of the babel entering the branch centrals that has to be straightened out and each separate series of voice undulations sent on its proper way, to be translated into speech again and poured into the proper ear. It is no wonder, then, that it has been found necessary to establish a school for telephone girls where they can be taught how to untangle the snarl and handle the vast, complicated system. In these schools the operators go through a regular course lasting a month. They listen to lectures and work out the instructions given them at a practice switchboard that is exactly like the service switchboard, except that the wires do not go outside of the building, but connect with the instructor's desk; the instructor calls up the pupils and sends messages in just the same way that the subscribers call "central" in the regular service.

At the terminal station of a great railroad, in the midst of a network of shining rails, stands the switchman's tower. By means of steel levers the man in his tower can throw his different switches and open one track to a train and close another; by means of various signals the switchman can tell if any given line is clear or if his levers do their work properly.

A telephone system may be likened, in a measure, to a complicated railroad line: the trunk wires to subscribers are like the tracks of the railroad, and the central station may be compared to the switch tower, while the central operators are like the switchmen. It is the central girls' business to see that connections are made quickly and correctly, that no lines are tied up unnecessarily, that messages are properly charged to the right persons, that in case of a break in a line the messages are switched round the trouble, and above all that there shall be no delay.

When you take your receiver off the hook a tiny electric bulb glows opposite the brass-lined hole that is marked with your number on the switchboard of your central, and the telephone girl knows that you are ready to send in a call—the flash of the little light is a signal to her that you want to be connected with some other subscriber. Whereupon, she inserts in your connection a brass plug to which a flexible wire is attached, and then opens a little lever which connects her with your circuit. Then she speaks into a kind of inverted horn which projects from a transmitter that hangs round her neck and asks: "Number, please?" You answer with the number, which she hears through the receiver strapped to her head and ear. After repeating the number the "hello" girl proceeds to make the connection. If the number required is in the same section of the city she simply reaches for the hole or connection which corresponds with it, with another brass plug, the twin of the one that is already inserted in your connection, and touches the brass lining with the plug. All the connections to each central station are so arranged and duplicated that they are within the reach of each operator. If the line is already "busy" a slight buzz is heard, not only by "central," but by the subscriber also if he listens; "central" notifies and then disconnects you. If the line is clear the twin plug is thrust into the opening, and at the same time "central" presses a button, which either rings a bell or causes a drop to fall in the private exchange station of the party you wish to talk to. The moment the new connection is made and the party you wish to talk to takes off the receiver from his hook, a second light glows beside yours, and continues to glow as long as the receiver remains off. The two little lamps are a signal to "central" that the connection is properly made and she can then attend to some other call. When your conversation is finished and your receivers are hung up the little lights go out. That signals "central" again, and she withdraws the plug from both holes and pushes another button, which connects with a meter made like a bicycle cyclometer. This little instrument records your call (a meter is provided for each subscriber) and at the same time lights the two tiny lamps again—a signal to the inspector, if one happens to be watching, that the call is properly recorded. All this takes long to read, but it is done in the twinkling of an eye. "Central's" hands are both free, and by long practice and close attention she is able to make and break connections with marvellous rapidity, it being quite an ordinary thing for an operator in a busy section to make ten connections a minute, while in an emergency this rate is greatly increased.



The call of one subscriber for another number in the same section, as described above—for instance, the call of 4341 Eighteenth Street for 2165 Eighteenth Street—is the easiest connection that "central" has to make.

As it is impossible for each branch exchange to be connected with every individual line in a great city, when a subscriber of one exchange wishes to talk with a subscriber of another, two central operators are required to make the connection. If No. 4341 Eighteenth Street wants to talk to 1748 Cortlandt Street, for instance, the Eighteenth Street central who gets the 4341 call makes a connection with the operator at Cortlandt Street and asks for No. 1748. The Cortlandt Street operator goes through the operation of testing to see if 1748 is busy, and if not she assigns a wire connecting the two exchanges, whereupon in Eighteenth Street one plug is put in 4341 switch hole; the twin plug is put into the switch hole connecting with the wire to Cortlandt Street; at Cortlandt Street the same thing is done with No. 1748 pair of plugs. The lights glow in both exchanges, notifying the operators when the conversation is begun and ended, and the operator of Eighteenth Street "central" makes the record in the same way as she does when both numbers are in her own district.

Besides the calls for numbers within the cities there are the out-of-town calls. In this case central simply makes connection with "Long Distance," which is a separate company, though allied with the city companies. "Long Distance" makes the connection in much the same way as the branch city exchanges. As the charges for long-distance calls depend on the length of the conversation, so the connection is made by an operator whose business it is to make a record of the length in minutes of the conversation and the place with which the city subscriber is connected. An automatic time stamp accomplishes this without possibility of error.

Sometimes the calls come from a pay station, in which case a record must be kept of the time occupied. This kind of call is indicated by the glow of a red light instead of a white one, and so "central" is warned to keep track, and the supervisors or monitors who constantly pass to and fro can note the kind of calls that come in, and so keep tab on the operators.

Other coloured lights indicate that the chief operator wishes to send out a general order and wishes all operators to listen. Another indicates that there is trouble somewhere on the line which needs the attention of the wire chief and repair department.



The switchboards themselves are made of hard, black rubber, and are honeycombed with innumerable holes, each of which is connected with a subscriber. Below the switchboard is a broad shelf in which are set the miniature lamps and from which project the brass plugs in rows. The flexible cords containing the connecting wires are weighted and hang below, so that when a plug is pulled out of a socket and dropped it slides back automatically to its proper place, ready for use.

Many subscribers nowadays have their own private exchanges and several lines running to central. Perhaps No. 4341 Eighteenth Street, for instance, has 4342 and 4344 as well. This is indicated on the switchboard by a line of red or white drawn under the three switch-holes, so that central, finding one line busy, may be able to make connection with one of the other two, the line underneath showing at a glance which numbers belong to that particular subscriber.

If a subscriber is away temporarily, a plug of one colour is inserted in his socket, or if he is behind in his payments to the company a plug of another colour is put in, and if the service to his house is discontinued still another plug notifies the operator of the fact, and it remains there until that number is assigned to a new subscriber.

The operators sit before the switchboard in high swivel chairs in a long row, with their backs to the centre of the room.

From the rear it looks as if they were weaving some intricate fabric that unravels as fast as it is woven. Their hands move almost faster than the eye can follow, and the patterns made by the criss-crossed cords of the connecting plugs are constantly changing, varying from minute to minute as the colours in a kaleido-scope form new designs with every turn of the handle.

Into the exchange pour all the throbbing messages of a great city. Business propositions, political deals, scientific talks, and words of comfort to the troubled, cross and recross each other over the black switchboard. The wonder is that each message reaches the ear it was meant for, and that all complications, no matter how knotty, are immediately unravelled.

In the cities the telephone is a necessity. Business engagements are made and contracts consummated; brokers keep in touch with their associates on the floors of the exchanges; the patrolmen of the police force keep their chief informed of their movements and the state of the districts under their care; alarms of fire are telephoned to the fire-engine houses, and calls for ambulances bring the swift wagons on their errands of mercy; even wreckers telephone to their divers on the bottom of the bay, and undulating electrical messages travel to the tops of towering sky-scrapers.



In Europe it is possible to hear the latest opera by paying a small fee and putting a receiver to your ear, and so also may lazy people and invalids hear the latest news without getting out of bed.

The farmers of the West and in eastern States, too, have learned to use the barbed wire that fences off their fields as a means of communicating with one another and with distant parts of their own property.

Mr. Pupin has invented an apparatus by which he hopes to greatly extend the distance over which men may talk, and it has even been suggested that Uncle Sam and John Bull may in the future swap stories over a transatlantic telephone line.

The marvels accomplished suggest the possible marvels to come. Automatic exchanges, whereby the central telephone operator is done away with, is one of the things that inventors are now at work on.

The one thing that prevents an unlimited use of the telephone is the expensive wires and the still more expensive work of putting them underground or stringing them overhead. So the capping of the climax of the wonders of the telephone would be wireless telephony, each instrument being so attuned that the undulations would respond only to the corresponding instrument. This is one of the problems that inventors are even now working upon, and it may be that wireless telephones will be in actual operation not many years after this appears in print.



A MACHINE THAT THINKS

A Typesetting Machine That Makes Mathematical Calculations

For many years it was thought impossible to find a short cut from author's manuscript to printing press—that is, to substitute a machine for the skilled hands that set the type from which a book or magazine is printed. Inventors have worked at this problem, and a number have solved it in various ways. To one who has seen the slow work of hand typesetting as the compositor builds up a long column of metal piece by piece, letter by letter, picking up each character from its allotted space in the case and placing it in its proper order and position, and then realises that much of the printed matter he sees is so produced, the wonder is how the enormous amount of it is ever accomplished.

In a page of this size there are more than a thousand separate pieces of type, which, if set by hand, would have to be taken one by one and placed in the compositor's "stick"; then when the line is nearly set it would have to be spaced out, or "justified," to fill out the line exactly. Then when the compositor's "stick" is full, or two and a half inches have been set, the type has to be taken out and placed in a long channel, or "galley." Each of these three operations requires considerable time and close application, and with each change there is the possibility of error. It is a long, expensive process.

A perfect typesetting machine should take the place of the hand compositor, setting the type letter by letter automatically in proper order at a maximum speed and with a minimum chance of error.

These three steps of hand composition, slow, expensive, open to many chances of mistake, have been covered at one stride at five times the speed, at one-third the cost, and much more accurately by a machine invented by Mr. Tolbert Lanston.

The operator of the Lanston machine sits at a keyboard, much like a typewriter in appearance, containing every character in common use (225 in all), and at a speed limited only by his dexterity he plays on the keys exactly as a typewriter works his machine. This is the sum total of human effort expended. The machine does all the rest of the work; makes the calculations and delivers the product in clean, shining new type, each piece perfect, each in its place, each line of exactly the right length, and each space between the words mathematically equal—absolutely "justified." It is practically hand composition with the human possibility of error, of weariness, of inattention, of ignorance, eliminated, and all accomplished with a celerity that is astonishing.



This machine is a type-casting machine as well as a typesetter. It casts the type (individual characters) it sets, perfect in face and body, capable of being used in hand composition or put to press directly from the machine and printed from.

As each piece of type is separate, alterations are easily made. The type for correction, which the machine itself casts for the purpose—a lot of a's, b's, etc.—is simply substituted for the words misspelled or incorrectly used, as in hand composition.

The Lanston machine is composed of two parts, the keyboard and the casting-setting machine. The keyboard part may be placed wherever convenient, away from noise or anything that is likely to distract or interrupt the operator, and the perforated roll of paper produced by it (which governs the setting machine) may be taken away as fast as it is finished. In the setting-casting machine is located the brains. The five-inch roll of paper, perforated by the keyboard machine (a hole for every letter), gives the signal by means of compressed air to the mechanism that puts the matrix (or type mould) in position and casts the type letter by letter, each character following the proper sequence as marked by the perforations of the paper ribbon. By means of an indicator scale on the keyboard the operator can tell how many spaces there are between the words of the line and the remaining space to be filled out to make the line the proper width. This information is marked by perforations on the paper ribbon by the pressure of two keys, and when the ribbon is transferred to the casting machine these space perforations so govern the casting that the line of type delivered at the "galley" complete shall be of exactly the proper length, and the spaces between the words be equal to the infinitesimal fraction of an inch.

The casting machine is an ingenious mechanism of many complicated parts. In a word, the melted metal (a composition of zinc and lead) is forced into a mold of the letter to be cast. Two hundred and twenty-five of these moulds are collected in a steel frame about three inches square, and cool water is kept circulating about them, so that almost immediately after the molten metal is injected into the lines and dots of the letter cut in the mould it hardens and drops into its slot, a perfect piece of type.

All this is accomplished at a rate of four or five thousand "ems" per hour of the size of type used on this page. The letter M is the unit of measurement when the amount of any piece of composition is to be estimated, and is written "em."

If this page were set by hand (taking a compositor of more than average speed as a basis for figuring), at least one hour of steady work would be required, but this page set by the Lanston machine (the operator being of the same grade as the hand compositor) would require hardly more than fifteen minutes from the time the manuscript was put into the operator's hands to the delivery complete of the newly cast type in galleys ready to be made up into pages, if the process were carried on continuously.

This marvellous machine is capable of setting almost any size of type, from the minute "agate" to and including "pica," a letter more than one-eighth of an inch high, and a line of almost any desired width, the change from one size to any other requiring but a few minutes. The Lanston machine sets up tables of figures, poetry, and all those difficult pieces of composition that so try the patience of the hand compositor.

It is called the monotype because it casts and sets up the type piece by piece.

Another machine, invented by Mergenthaler, practically sets up the moulds, by a sort of typewriter arrangement, for a line at a time, and then a casting is taken of a whole line at once. This machine is used much in newspaper offices, where the cleverness of the compositor has to be depended upon and there is little or no time for corrections. Several other machines set the regular type that is made in type foundries, the type being placed in long channels, all of the same sort, in the same grooves, and slipped or set in its proper place by the machine operated by a man at the keyboard. These machines require a separate mechanism that distributes each type in its proper place after use, or else a separate compositor must be employed to do this by hand. The machines that set foundry type, moreover, require a great stock of it, just as many hundred pounds of expensive type are needed for hand composition.



Though a machine has been invented that will put an author's words into type, no mechanism has yet been invented that will do away with type altogether. It is one of the problems still to be solved.



HOW HEAT PRODUCES COLD

ARTIFICIAL ICE-MAKING

One midsummers day a fleet of United States war-ships were lying at anchor in Guantanamo Bay, on the southern coast of Cuba. The sky was cloudless, and the tropic sun shone so fiercely on the decks that the bare-footed Jackies had to cross the unshaded spots on the jump to save their feet.

An hour before the quavering mess-call sounded for the midday meal, when the sun was shining almost perpendicularly, a boat's crew from one of the cruisers were sent over to the supply-ship for a load of beef. Not a breath was stirring, the smooth surface of the bay reflected the brazen sun like a mirror, and it seemed to the oarsmen that the salt water would scald them if they should touch it. Only a few hundred yards separated the two vessels, yet the heat seemed almost beyond endurance, and the shade cast by the tall steel sides of the supply-steamer, when the boat reached it, was as comforting as a cool drink to a thirsty man. The oars were shipped, and one man was left to fend off the boat while the others clambered up the swaying rope-ladder, crossed the scorching decks on the run, and went below. In two minutes they were in the hold of the refrigerator-ship, gathering the frost from the frigid cooling-pipes and snowballing each other, while the boat-keeper outside of the three-eighth-inch steel plating was fanning himself with his hat, almost dizzy from the quivering heat-waves that danced before his eyes. The great sides of beef, hung in rows, were frozen as hard as rock. Even after the strip of water had been crossed on the return journey and the meat exposed to the full, unobstructed glare of the sun the cruiser's messcooks had to saw off their portions, and the remainder continued hard as long as it lasted. But the satisfaction of the men who ate that fresh American beef cannot be told.

Cream from a famous dairy is sent to particular patrons in Paris, France, and it is known that in one instance, at least, a bottle of cream, having failed to reach the person to whom it was consigned, made the return transatlantic voyage and was received in New York three weeks after its first departure, perfectly sweet and good. Throughout the entire journey it was kept at freezing temperature by artificial means. These are but two striking examples of wonders that are performed every day.



Cold, of course, is but the absence of heat, and so refrigerating machinery is designed to extract the heat from whatever substance it is desired to cool. The refrigerating agent used to extract the heat from the cold chamber must in turn have the heat extracted from it, and so the process must be continuous.

Water, when it boils and turns into steam or vapour, is heated by or extracts heat from the fire, but water vapourises at a high temperature and so cannot be used to produce cold. Other fluids are much more volatile and evaporate much more easily. Alcohol when spilt on the hand dries almost instantly and leaves a feeling of cold—the warmth of the hand boils the alcohol and turns it into vapour, and in doing so extracts the heat from the skin, making it cold; now, if the evaporated alcohol could be caught and compressed into its liquid form again you would have a refrigerating machine.

Alcohol is expensive and inflammable, and many other volatile substances have been discarded for the one or the other reason. Of all the fluids that have been tried, ammonia has been found to work most satisfactorily; it evaporates at a low temperature, is non-inflammable, and is comparatively cheap.

The hold of the supply-ship mentioned at the head of this chapter was a vast refrigerator, but no ice was used except that produced mechanically by the power in the ship. To produce the cold in the hold of the ship it was necessary to extract the heat in it; to accomplish this, coils ran round the space filled with cold brine, which, as it grew warm, drew the heat from the air. The brine in turn circulated through a tank containing pipes filled with ammonia vapour which extracted the heat from it; the brine then was ready to circulate through the coils in the hold again and extract more heat. The heat-extracting or cooling power of the ammonia is exerted continually by the process described below. Ammonia requires heat to expand and turn into vapour, and this heat it extracts from the substance surrounding it. In this marine refrigerating machine the ammonia got the heat from the brine in the tank, then it was drawn by a pump from the pipes in the tank, compressed by a power compressor, and forced into a second coil. The second coil is called a condenser because the vapour was there condensed into a fluid again. Over the pipes of the condenser cool water dripped constantly and carried off the heat in the ammonia vapour inside the coils and so condensed it into a fluid again—just as cold condenses steam into water. The compressor-pump then forced the fluid, ammonia through a small pipe from the condenser coils to the cooling coils in the tank of brine. The pipes of the cooling coils are much larger than those of the condenser, and as the fluid ammonia is forced in a fine spray into these large pipes and the pressure is relieved it expands or boils into the larger volume of vapour and in so doing extracts heat from the brine. The pump draws the heated vapour out, the compressor makes it dense, and the coils over which the cool water flows condenses it into fluid again, and so the circuit continues—through cooler, pump, compressor, and condenser, back into the cooling-tank.

In the meantime, the cold brine is being pumped through the pipes in the hold of the ship, where it extracts the heat from the air and the rows of sides of beef and then returns to the cooling-tank. In the refrigerating plant, then, of the supply-ship, there were two heat-extracting circuits, one of ammonia and the other of brine. Brine is used because it freezes at a very low temperature and continues to flow when unsalted water would be frozen solid. The ammonia is not used direct in the pipes in a big space like the hold of a ship, because so much of it would be required, and then there is always danger of the exposed pipes being broken and the dangerous fumes released.

Opposite as it may seem, heat is required to produce cold—for steam is necessary to drive the compressor and pump of a refrigerating plant, and fire of some sort is necessary to make steam.

The first artificial refrigerating machines produced cold by compressing and expanding air, the compressed air containing the heat being cooled by jets of cool water spirted into the cylinder containing it, then the compressed air was released or expanded into a larger chamber and thereby extracted the heat from brine or whatever substance surrounded it.

It is in the making of ice, however, that refrigerating machinery accomplishes its most surprising results. It was said in the writer's hearing recently that natural ice costs about as much when it was delivered at the docks or freight-yards of the large cities of the North as the product of the ice-machine. Of course, the manufactured ice is produced near the spot where it is consumed, and there is little loss through melting while it is being stored or transported, as in the case of the natural product.

There are two ways of making ice—or, rather, two methods using the same principle.

In the can system, a series of galvanized-iron cans about three and a half feet deep, eight inches wide, by two and a half feet long are suspended or rested in great tanks of brine connecting with the cooling-tank through which the pipes containing the ammonia vapour circulates. The vapour draws the heat from the brine, and the brine, which is kept moving constantly, in turn extracts the heat from the distilled water in the cans. While this method produces ice quickly, it is difficult to get ice of perfect clearness and purity, because the water in the can freezes on the sides, gradually getting thicker, retaining and concentrating in the centre any impurities that may be in the water. The finished cake, therefore, almost always has a white or cloudy appearance in the centre, and is frequently discolored.

In an ice-plant operated on the can system a great many blocks are freezing at once—in fact, the whole floor of a great room is honeycombed with trap-doors, a door for each can. The freezing is done in rotation, so that one group of cans is being emptied of their blocks of ice while others are still in process of congealing, while still others are being filled with fresh water. When the freezing is complete, jets of steam or quick immersion of the can in hot water releases the cake and the can is ready for another charge.

The plate system of artificial ice-making does away with the discoloration and the cloudiness, because the water containing the impurities or the air-bubbles is not frozen, but is drawn off and discarded.

In the plate system, great permanent tanks six feet deep and eight to twelve feet wide and of varying lengths are used. These tanks contain the clean, fresh water that is to be frozen into great slabs of ice. Into the tanks are sunk flat coils of pipe covered with smooth, metal plates on either side, and it is through these pipes that the ammonia vapour flows. The plates with the coils of pipe between them fit in the tank transversely, partitioning it off into narrow cells six feet deep, about twenty-two inches wide, and eight or ten feet long. In operation, the ammonia vapour flows through the pipes, chilling the plates and freezing the water so that a gradually thickening film of ice adheres to each side of each set of plates. As the ice gets thicker the unfrozen water between the slabs containing the impurities and air-bubbles gets narrower. When the ice on the plates is eight or ten inches thick very little of the unfrozen water remains between the great cakes, but it contains practically all the impurities. When the ice on the plates is thick enough, the ammonia vapour is turned off and steam forced through the pipes so the cakes come off readily, or else plates, cakes, and all are hoisted out of the tank and the ice melted off. The ice, clear and perfect, is then sawed into convenient sizes and shipped to consumers or stored for future use. Sometimes the plates or partitions are permanent, and, with the coils of pipes between them, cold brine is circulated, but in either case the two surfaces of ice do not come together, there being always a film of water between.

Still another method produces ice by forcing the clean water in extremely fine spray into a reservoir from which the air has been exhausted—into a vacuum, in other words; the spray condenses in the form of tiny particles of ice, which are attached to the walls of the reservoir. The ice grows thicker as a carpet of snow increases, one particle falling on and freezing to the others until the coating has reached the required thickness, when it is loosened and cut up in cakes of convenient size. The vacuum ice is of marble-like whiteness and appearance, but is perfectly pure, and it is said to be quite as hard.

More and more artificial ice is being used, even in localities where ice is formed naturally during parts of the year.

Many of the modern hotels are equipped with refrigerating plants where they make their own ice, cool their own storage-rooms, freeze the water in glass carafes for the use of their guests, and even cool the air that is circulated through the ventilating system in hot weather. In many large apartment-houses the refrigerators built in the various separate suites are kept at a freezing temperature by pipes leading to a refrigerating plant in the cellar. The convenience and neatness of this plan over the method of carrying dripping cakes from floor to floor in a dumb-waiter is evident.

Another use of refrigerating plants that is greatly appreciated is the making of artificial ice for skating-rinks. An artificial ice skating-rink is simply an ice machine on a grand scale—the ice being made in a great, thin, flat cake. Through the shallow tanks containing the fresh water coils of pipe through which flows the ammonia vapour or the cold brine are run from end to end or from side to side so that the whole bottom of the tank is gridironed with pipes, the water covering the pipes is speedily frozen, and a smooth surface formed. When the skaters cut up the surface it is flooded and frozen over again.

So efficient and common have refrigerating plants become that artificially cooled water is on tap in many public places in the great cities. Theatres are cooled during hot weather by a portion of the same machinery that supplies the heat in winter, and it is not improbable that every large establishment, private, or public, will in the near future have its own refrigerating plant.

Inventors are now at work on cold-air stoves that draw in warm air, extract the heat from it, and deliver it purified and cooled by many degrees.

Even the people of this generation, therefore, may expect to see their furnaces turned into cooling machines in summer. Then the ice-man will cease from troubling and the ice-cart be at rest.

THE END