Though one or more means of transmitting messages by electricity have been known now for a great many years, the mechanisms by which they are accomplished are understood only by those who take a general interest in physical science, and the few to whom electrical communication is a profession. So far as theory and details of working are concerned, there are a good many people still in the same shadowy frame of mind as the old Aberdeen postmaster, of whom the story is told. When asked to explain the working of a telegraph instrument he said, “Look at that sheep-dog. Suppose we hold his hind-quarters here and stretch him out until his head reaches Glasgow. Then if we tread on his tail here he will bark in Glasgow. As it is not convenient to stretch a dog, we stretch a wire, and that serves the purpose.”

As the name implies, “stretching a wire” is unnecessary in wireless telegraphy, though in order to understand the finer points of theory one needs to stretch the imagination a little. That, however, is not so much, because there is any inherent obscurity or difficulty in the underlying principles, as because the mechanism of all electrical effects is more or less intangible. Electricity and magnetism operate across apparently empty space, and the links which connect cause and effect have to be guessed at.

Three different methods have been made use of in wireless telegraphy, which may be classed as conduction, induction and wave methods. In the first method currents are sent through the earth from an electrode to another at the sending station. In induction, use is made of the property which alternating currents possess of exciting similar currents in neighboring conductors, the aim being to get as intense a current as possible in the secondary circuit. Mr. W.H. Preece, of England, by combining the two, signaled in this way as far as forty miles. The third and the only method which has proved practically available is by the use of electro-magnetic waves.

Guglielmo Marconi, an Italian, after long experiment, patented in 1897 a method entirely independent of wires, the electric waves being sent, presumably, through the ether, by the aid of a transmitting apparatus, and being detected by a coherer, a glass tube filled with metallic filings, into the end of which the terminals of a relay circuit enter. The wave falls on conducting material and, the spark gap being replaced by a coherer, the metallic filings magnetically cling together, closing the relay circuit, so that a signal is made. On breaking the current, a slight tap on the coherer or other means breaks the cohesion of the filings and the relay circuit is broken. In this way a rapid succession of signals can be sent.

In 1899 Marconi conducted in England an exhaustive series of successful experiments, sending messages across the English Channel from the South Foreland to the French coast near Boulogne, and extending his results until much longer distances were covered. The process of development was continued until, to the world’s astonishment, signals were sent across the Atlantic and, finally, commercial messages were transmitted over this distance.

Marconi’s system is based on the property supposed to be exerted by the vibrations or waves of electric currents passing through a wire of setting up similar vibrations in the ether of space. These waves extend in every direction from the point of departure, and by ingenious and very delicate receiving instruments their presence in space is indicated and they are taken up in sufficient strength to repeat their pulsations and in this way reproduce the signals sent from the transmitter. One difficulty hitherto has been that a message may be received by hundreds of receiving instruments in all directions, thus preventing secrecy. Many efforts have been made to overcome this defect, but as yet with only partial success.

The distance to which messages can be sent has so far depended largely on the height to which the wires extend above the earth’s surface, lofty poles being erected at the stations. The height of these has been gradually increased until the Eiffel Tower at Paris has been utilized as a sending station. The strength of the electric waves has been similarly increased to add to their space-penetrating capacity. The record of wireless telegraphy has been in this way improved until now it has come into daily competition with other means of news sending. Methods of tuning the instruments have been adopted which limit the influence of the currents to properly tuned receivers and in this way some degree of secrecy is attained.

Though the honor of inventing the art of wireless telegraphy is generally ascribed to Marconi, this is to give him more credit than he deserves. The principles involved were discovered by others and the utmost done by him was to invent a practical method of applying them. There are other systems of wireless telegraphy of later invention than that of Marconi, through a different application of the same principles.

Messages have been sent to enormous distances, far surpassing the width of the Atlantic, as from Nova Scotia and Ireland to Argentina, a distance of 5,600 miles. Under exceptional conditions a distance of 6,500 miles has been attained, but the daily effective range of the best equipped stations is little over 3,000 miles. For overland messages the limit of distance is about 1,000 miles.

There are a number of kinds of interference which arise from electrical disturbances in the earth’s atmosphere. A flash of lightning is liable to give rise to a wave of enormous power which will set half the aerials on the earth vibrating in spite of the differences of pitch to which they are tuned. Thunderstorms are at their worst in the summer in temperate latitudes, but they occur to some extent all the year round, and those in the tropics are of extreme violence. As a consequence it is frequently almost impossible to decipher earthly messages owing to the imperious signals from the clouds. Of the various methods adopted for choking off the “atmospherics,” as the disturbances are called, one is to use receiving circuits which respond only to a narrow range of oscillations very different from those produced by a lightning flash. The employment of a high-pitched musical note in the telephone is also an advantage because its extreme regularity distinguishes it from the marked irregularity of the stray waves.

On the palatial passenger steamers that plow the Atlantic the Marconi apparatus enables the travelers to keep in touch with their friends, to transact important business on either side of the water, and to secure a continuity of life which was formerly divided by a sea voyage. All the larger vessels now publish a daily paper on board, the news in which has been supplied by the same agencies who feed the newspaper on land. Information is flashed to meet or overtake the vessel and caught up by her aerial, as she pursues her way at twenty-five or thirty miles an hour.

In the case of cargo vessels, the owners are able to get into touch with them at any point of their voyage. They can advise the captain where to call for coal or cargo, while he on his part can get into communication with the authorities or his firm’s agents at the port of call, and have every necessary or desirable preparation made for his arrival. Should an accident happen, he can call assistance, inform the owners or relieve anxiety and suspense. At no time is he isolated from the world. The fortitude, courage and daring of those “who go down to the sea in ships” has never been called into question, but it has if anything been emphasized by the receipt of messages from an operator at his post, to whom the bonds of duty were as bonds of steel, and who calmly operated the key until the waves entered his cabin and brought him honorable release.

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Relief has been brought in this way to vessels in distress and many lives saved. An important example is that of the sinking of the Titanic in 1912. By means of wireless messages from ship to ship the width of the Pacific has been practically covered, as ships en route from America to Australia or Asia can be kept in touch with Honolulu through almost the entire journey. A law in the United States now requires that all ocean passage-steamers carrying fifty or more passengers on routes of 200 miles or over must be equipped with efficient wireless apparatus and operators. The distance reached must be at least 100 miles. The Canadian law provides that every sea-going and coasting passenger ship of over 400 tons gross, registered in Canada, and every sea-going and coasting freight ship of over 1,200 tons gross, shall be equipped with a wireless apparatus. Wireless messages have been successfully sent from aeroplanes, balloons and submarine vessels, and the naval vessels of all nations are kept in easy communication by this method. Wireless press messages between America and Europe are also matters of daily performances.

What is Forestry Work?

A Division of Forestry was organized in the Department of Agriculture, some years ago, and the most earnest efforts are being made to prevent any needless waste of our timber lands.

The usefulness of forests to man lies: (1) In furnishing him with timber for building, manufacturing, fuel, etc., and with various other useful products of trees. (2) In their influence on climate. (3) In their influence on water-flow, by keeping the ground more moist, making the outflow more regular, checking the rapid melting of snow, and keeping the hillsides from being denuded of their soil, thus setting up streams and covering cultivated valley lands. The necessity of a proper preservation of the forests seems highly evident, but the nations have been slow in waking up to this fact. Several of the countries of Europe have been largely stripped of their woodlands by indiscreet cutting in the poorest countries, and only recently have the nations been roused to the necessity of their conservation. This is now being carefully attended to in several countries, especially Germany. In China broad mountain regions have been stripped of their trees, with the result that this soil has been swept away by the rains, leaving the rocks bare, while broad reaches of formerly fertile lowlands have been made sterile by the material spread over them by the rains that swept the mountain slopes.

In the United States the broad original forests have been very largely cut away, and those remaining have of late years been so largely reduced by indiscriminate cutting and the ravages of carelessly kindled fires that great alarm is felt as to the future of the lumber supply. Within recent years vigorous efforts have been made to overcome this growing evil. The American Forestry Association, founded in 1882, its purpose being the conservative use of our forest resources, has now over 5,000 members, residents of every state, and of Canada and foreign countries. The first State Forest Commission was organized by New York in 1885 and has now a very large forest reserve set aside in the Adirondacks. Pennsylvania has also large forest reserves in its mountain districts, and many other states have taken similar action. The art of forestry is also being taught in the schools, and a large body of skilled foresters are now in the service of the states and the general government. In the new and active movement for the conservation of national resources the preservation of the public forests ranks high, and to aid in this purpose the government has withdrawn as national forest areas a vast amount of the public lands, amounting at the present time to 192,931,197 acres, an area about equal to that of Texas and Ohio combined. These woodlands are under the charge of the National Forest Service and cared for by about 3,000 men, of whom 250 are professional foresters. The trees in these forests are cut with careful discrimination, and new trees are planted to take their place, there being forest nurseries containing about 20,000,000 plants and capable of supplying 18,000,000 a year. New York has 1,600,000 acres in its forest reserve, Pennsylvania over 920,000, and the reserves of the other states amount to a very considerable area.

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How did the Fashion of Wearing Cravats Commence?

Cravats get their name from the French “cravate,” meaning a croat, because this piece of dress was adopted in the eleventh century from the Croats who entered the French service. Towards the end of the eighteenth and the beginning of the nineteenth century the cravat attained an incredible degree of extravagance, but common sense at last brought in the simpler style of neckties that has since prevailed.

How does the Gas Meter Measure Your Gas?

The quantity of gas used by each consumer is measured by an instrument called a meter, of which there are two classes—the wet and the dry.

The wet meter is composed of an outer box about three-fifths filled with water. Within this is a revolving four-chambered drum, each chamber being capable of containing a definite quantity of gas, which is admitted through a pipe in the center of the meter, and, owing to the arrangement of the partitions of the chambers, causes the drum to maintain a constant revolution. This sets in motion a train of wheels carrying the hands over the dials which mark the quantity of gas consumed.

The dry meter consists of two or three chambers, each divided by a flexible partition or diaphragm, by the motion of which the capacity on one side is diminished while that on the other is increased. By means of slide valves, like those of a steam engine, worked by the movement of the diaphragms, the gas to be measured passes alternately in and out of each space. The contractions and expansions set in motion the clockwork which marks the rate of consumption. The diaphragms in all the chambers are so connected that they move in concert.

What is a Game Preserve?

Game preserves have only been introduced comparatively recently in the United States, for the hunting grounds have been freely open to the hunter, but they have been common in Britain and other countries of Europe for centuries.

Their purpose here is the preservation and increase of wild animals instead of their destruction.

Deer parks have long been kept in this country, but the first systematic attempt to foster wild game was made about 1860 by Judge J.D. Caton in a park of Ottawa, Ill.

Chief among those that followed on a large scale is the great game park of Austin Corbin, near Newport, N.H., an enclosure of 36,000 acres, in which a wire fence eight feet high encloses an oblong tract twelve by five miles, through which passes a mountain range 3,000 feet high. American game of all kinds are kept here, from buffalo, elk, and moose to the smaller and more timid varieties, and there has been a rapid increase.

Dr. J. Seward Webb has a 9,000-acre preserve in the Adirondacks, and various other large parks have been established elsewhere, in which our fast-disappearing game animals are augmenting in numbers and game birds of foreign origin have been introduced.