Page images
PDF
[graphic][merged small]

work among local authorities in a hopeless sort of maze so that no one has any power or money to do anything effectively. Maryland, up to 1909, extended the same absurdity to State supervision by dividing authority for construction between the State Geological Survey and the State Highway Commission.

By way of contrast Wisconsin, having adopted the war cry, "A dollar's worth of road for every dollar of tax," is showing how to make money work miracles. In 1907 as v "h as $10,000 was appropriated for the of the State Geological Survey in ex, . .imental road building and in advising local road authorities. As there are fifteen hundred of these local road bodies, the contract was rather a large one. But the Survey engineers did the best they could by addressing public meetings and distributing pamphlets, and by establishing a correspondence school for road builders. In order to make every dollar count they managed to induce some localities to build roads graded to a width of twentyfour feet with a stone surface only nine feet wide. Everybody knew that such a narrow roadway would not answer at all, but after they had tried them they wanted no other kind. These nine-foot roadways answer the purposes of light traffic and they cost but $1,800 to $3,500 per mile, while the 14-foot stone surface, which allows two teams to pass and which is used for heavier traffic, costs from $3,000 to $5,000 per mile.

Every community which reaches the point of determining to have real roads

and raises the money to pay for them does not get what it wants. Some counties in California paid for good roads, or thought they did, but the work was so badly done that the good roads movement received a setback. On the other hand there was Pike County, Alabama, which raised money to pay for gravel and macadam roads, but wisely sent to the U. S. Office of Public Roads for an engineer to build them. lie. found sandclay roads, costing one-fifth of what macadam would cost, better suited to the locality. In Kansas sand-clay roads cost from $707 to $1,183 per mile, which seems to bring them well within the limit required to interest the average farmer in highway improvement, according to the opinion of the (rood Rpads Convention which met at Cleveland in 1909.

This does not prove that sand-clay roads should be built everywhere under all conditions. The true moral to be drawn from the experience of l'ike County is always and under all circumstances to employ a highway engineer to direct operations. Road building is an art that calls for something more than good intentions.

An interesting feature of the highway situation is the passing of macadam construction, for many years regarded as the highest type of road. But the advent of the automobile has utterly destroyed the reputation of the macadam road. It has been found by costly experience that no ordinary water bound macadam is capable of withstanding for any length of time the action of excessive automobile traffic, and in Massachusetts actual count shows that automobiles make up forty-two per cent, of the traffic on the highways of the State. The speeding rubber tires whirl away the rock dust, thus destroying the bond of the wearing surface, then ravel out the*larger fragments of stone. Some sort of binder that will hold material, both fine and coarse, together is absolutely necessary. The question is so important that the American society of Civil Engineers has appointed a special committee to investigate. Various combinations of tar, asphalt, and crude petroleum have been tried in various localities with different degrees of success. It is already evident that a bituminous binder that will work well under one set of conditions will not answer at all under other conditions. The difficulty is to suit the binder to the requirements of the traffic and the climate.

Some other points which should be possessed by a good road according to the concensus of opinion of the world's foremost highway engineers, as formulated in the conclusions of the First International Road Congress, held at Paris in October, 1908, and of the second Congress held at Brussels in August, 1910, are as follows:

The minimum width of roadway should be 19 feet 8 inches.

The camber should be the least that will allow the proper run-off of rain water.

Grades should be moderate, with as little difference as possible between minimum and maximum.

Curves should have as great a radius as possible, but not less than 164 feet. Curves should be connected with tangents by parabolic curves. Curves should be slightly raised at the outside, but not enough to interfere with ordinary vehicles. The view at curves should not be obstructed.

Road crossings should be visible and well opened out. Railroad and tramway crossings at grade should be avoided if it is possible to do so; otherwise they

should be signalled night and day.

Wherever possible tracks should be provided for bicyclists and paths for horsemen.

The sides of roads should be defined by trees wherever possible.

Binding material should be used in the construction of metalled (broken stone) roadways, "special attention being given to determining the character of the binder best suited to local conditions.

Superficial tarring may be considered as definitely accepted in practice.

Emulsions of tar, oil, or hydroscopic salts have a real but not a lasting efficiency. Therefore, their use should be limited to special cases such as race courses.

Cross and longitudinal sections of roads and gutters should facilitate the flow of trickling water and prevent infiltration.

That maintenance is quite as important as construction is well understood in Europe where fourteen nations spend $160,000,000 annually for the maintenance of 994,000 miles of road which cost $5,000,000,000 to build. In the United States, unfortunately, the importance of constant care has not been realized as clearly as it should have been. But in this particular, too, marked improvement is noticeable. New York, which leads the Nation in the magnitude and comprehensiveness of its highway improvement programme, has copied the patrol system that has made the roads of France so famous. The road patrolmen in New York furnish their own horse, cart, and tools and keep the highways in first-class condition at a cost of $75 per mile per year for labor and $25 per mile for material. Oil is successfully used to lay the dust, the plague due chiefly to the automobiles, at a cost of $422 per mile of sixteen-foot roadway per year.

To sum up the situation in a sentence, there are so many hopeful signs of improvement everywhere that it seems safe to predict that within ten years the administration of the public roads will be established upon a satisfactory basis.

MANY TALK ON ONE WIRE

By

RENE BACHE

* t X T ELLO! Is this New York?" | I "Yes."

I I "This is Honolulu, in the 1 I Hawaiian Islands. Give

JL JL me the Flatiron Building."

That is the sort of long-distance telephoning we shall soon be able to do. Indeed, there is every prospect that within a short time people will talk from Chicago to London over a wire. We may even send a whisper direct from Boston to Peking, China, or actually transmit a spoken message around the world!

All of this as the result of an invention just patented by Major George O.

[graphic][ocr errors]

Squier, of the Signal Corps, United States Army. He has made a free gift of it, however, to the American people, and anybody is at liberty to use it without paying a cent for the privilege.

The invention does not merely promise to provide a means whereby one may telephone for a distance almost indefinite. It also makes practicable the employment of a single wire for the simultaneous sending of a number of messages, wnether by the voice or by the telegraph.

Briefly described, the method adopted is one whereby wireless messages are sent over a wire—a sort of "wire wireless," as Major Squier calls it. A paradox, one might say. But the matter will be better understood when it is explained that the messages travel not through the wire itself, but through a thin layer of etber surrounding the wire. All that the wire does is to act as a guide.

Everybody is familiar with the enormously tall poles erected for wireless telegraphy. Such an "antenna," as it is called, sends out electro-magnetic vibrations which expand like the circles made by a stone which a small boy throws into a pond. It follows, of course, that their effect at any particular distant place is relatively infinitesimal. But, if all of these vibrations were bunched together and sent in a single direction, it is obvious that they could be rendered a million times more efficient, so far as the carrying of vibrations to a given point is concerned.

Now, this is exactly what is accomplished by the invention here described, which, by the way, does not require the use of any new apparatus whatever. The ordinary telephonic outfit, as it exists today, may be used, without the addition of a single instrument. What Major Squier has patented is merely a new method, by which it is practicable to send extra conversations by the wire.

[graphic]

WHERE THE EXPERIMENTS WITH THE MULTIPLEX TELEPHONE WERE CONDUCTED. Signal Office Research Laboratory at the Bureau of Standards, Washington.

At the bottom of the idea upon which the invention is based lies the fact that the electro-magnetic rays which pass over a telephone wire are audible only within definite limits of frequency. If the vibrations are fewer than sixteen to the second, they transmit no impression to the human ear. On the other hand, if they number more than 20,000 to the second, the human auditory apparatus is unable to respond to them, and so perceives nothing'. In other words, our ears are deaf to vibrations above 20,000 per second, and below- sixteen vibrations.

To carry his messages. Major Squier employs high-frequency waves, far above the limit of human hearing. Obtaining them from a dynamo, he tunes them to various pitches, so that each conversation carried on over the wire is based upon a separate and particular number of vibrations per second. Inasmuch as the talks are on different electrical tunes, they do not interfere with one another in the least.

It will be understood, then, that high

frequency waves, suitably tuned, are traveling along the telephone wires—not in the wire itself, but in a layer of ether surrounding it. They cannot be called sound waves, because they are too rapid to produce an impression upon the human ear. Major Squier calls them "ultra-sound vibrations." Nevertheless, each voice that speaks into the transmitter affects these waves differently, and every spoken word is faithfully carried by them. W hen, therefore, at the other end of the line, they are retranslated back into sound waves, the message becomes audible to the listener.

Instead of an ordinary direct current through the wire itself, impulses are sent along it in the shape of high-frequency waves which, as the inventor says, "don't get into the wire at all." If it be asked how many "extra conversations" can be put on the conductor, the only possible answer is "several," because the number must depend upon the diameter of the wire and other conditions.

As the frequency of th« electro-magnetic waves increases, their energy appears to have a steady growing tendency

JS to get out of the wire itself. The ordinary battery telephonic current is largely a conduction current through metal, and the ohmic resistance of the wire is one of the principal obstacles to long-distance telephoning. On the other hand, in wireless telegraphy, frequencies from 100,000 up to several millions per second are used, and the energy is chiefly radiated into the ether of space.

[graphic]

ONE HUNDRED THOUSAND CYCLE GENERATOR FOR ELECTRIC WAVES USED BY MAJOK SOWER IN HIS EXPERIMENTS.

There is, however, an intermediate range, in which the vibrations are from 20.000 to 100,000 per second, and wherein the electro-magnetic energy is still sufficiently linked to the wire to prevent excessive radiation into the ether. The wire, while carrying but a small part of the energy, nevertheless acts as an efficient guide for the high-frequency waves. Accordingly, use is made of these steered ether waves as a vehicle to carry telephonic or telegraphic messages.

It will thus be seen that the new invention combines the principles of wireless telegraphy and telephony with those of telegraphy and telephony by wire. Major Squier, in other words, has taken the apparatus and methods now used in wireless communication, and has applied them to the transmission of electro-magnetic waves along metal conductors, thus accomplishing an enormous improvement in efficiency over the plan of employing antennae at transmitting and re

ceiving stations, which is the ordinary custom.

The circuits are ordinary telephonic circuits, such as are now utilized in wire telephony and telegraphy. "In fact," says the inventor, '"the regular twistedpair paper-insulated lead-covered telephone cable serves the purpose very well, the energy being conveyed principally in the minute layer of ether separating the two metallic conductors. By this means a most efficient system of high-frequency telephony or telegraphy is maintained, and, at the same time, any interferences between neighboring circuits operated by the system are eliminated, so that many such circuits may be brought to the same switchboard without interfering effects."

The inventor further says: "Since a plurality of high-frequency waves of different frequencies may be impressed on the same line, and since these may be selectively separated from each other by suitably tuned circuits, it is obvious that multiplex telephony is practicable. Also, it has been found that these high-frequency waves may exist on the same line with ordinary battery telephonic currents without in any way affecting them; and thus the system may be applied to the usual telephonic circuit without 'cross talk' or other disturbances."

Major Squier calls attention' to the

« PreviousContinue »