Wireless Telegraphy.

Progress, Volume VI, Issue 9, 1 July 1911, Page 716

Wireless Telegraphy.

The Paris Wireless Telegraph Station. (From Our Own Correspondent.) Paris, March 20. The various practical applications of wireless telegraphy have of late years aroused great interest, not only among scientists and engineers, but in the general public throughout the world. Not the least important of such applications is the service which it appears destined to render to navigators. With a view to keeping New Zealand readers au courant with the progress in this direction I recently made several visits of inquiry, and in the subsequent paragraphs I am presenting some of the principal facts that came under my notice. • . , Au Interesting Subject. The rigorously exact determination of the position of a vessel at sea has at all times been a subject claiming close attention and study from those interested in navigation. The methods of astronomical and chronometrical observations in use up to the present, although they yield approximately exact results, are not free from the risk of errors which may involve serious consequences. The application of radio-teiegrapny to the transmission of time snoiuci, However, soon suppress every possibility of error. The multiplication of the stations in communication with one anotner will in the near future enable the surface of the entire globe to be covered oy means of the Hertzian waves. The latest' improvements directed in wireless teiegrapny will rapidly lead to the achievement of this result.

it acu o- teiegrapny renders it possible to transmit- to aii ships within a radius of okjvu Kilometres or more a given time, say tne nour of noon, maenema ticaliy exact wunm one-tenth of a second, the speed of ine Hertzian waves being almost equal to unit or light, bOU,bdU kilometres a second, Tins puts the sailor in possession of the cnronometric time, which assures the determination of the exact spot where the vessel is at that moment; that is to say, enables him to calculate the longitude and latitude of the place with absolute exactitude. Importance of Exactitude. And the importance of this exactitude in the knowledge of the time, by means of which most serious errors can be avoided, will be appreciated oy everyone who reflects that the best marine chronometers in use may, after a few weeks or

months of navigation, be subject to variations of two or three seconds or more, and that each error of one second in the time corresponds with an error of 450 metres in regard to the exact position of the ship. The new method was first experimented with in June last. At that date an increase in the power of the electric batteries and improvements in the other instruments employed at the Eiffel Tower enabled long-distance radio-telegraphic signals to be sent and received. Certain wireless telegraphy stations in the United States which have water power at their disposal and are thus able to produce large quantities of electric energy had already sent electric waves as far as Europe, where they were registered by sensitive apparatus. And a serious effort is being made in Prance to equip the principal radio-tele-graphic stations, and notably that of Paris, with instruments and electric energy to ensure that signals may . be transmitted and received with certainty and regularity. In order to ascertain the working of this important service I decided to investigate the . question of the transmission of the hour, and for this purpose two visits seemed to' me to be of equal importanceone to the Observatory, the other to the Laboratory at the Eiffel Tower. At the Observatory. The approaches to the Observatory have a severe aspect quite appropriate to the temple of the most ancient of human sciences. Passing through the gate and little garden laid out in geometric patterns, around which stand the pavilions where the modern disciples of Prometheus are engaged in wresting from the infinite the tell-tale image of the stars, if not the heavenly fire, one enters the sanctuary, rendered so illustrious by great discoveries, through a low archway which evokes ideas of a crypt.

There, on the silent ground floor, with walls more than two metres thick and covering over deep catacombs, were originally installed the clocks, instruments of precision, designed to serve as standards in the verification of the mean time, faultless dials whose truthful hands with their absolute synchronism have realised the ideal of Charles V. after a lapse of four centuries.

But even the shelters, which seem the most secure are liable, it appears, to be affected by certain climatic influences. After the inundations the whole installation of horary instruments was removed to the first floor. Under its fine rotunda, ornamented by portraits and astronomical instruments, the assistant astronomers quietly take their observations beneath the high windows which illuminate the spot where Louis XIV. visited Cassini, a scene of which Lebrun’s famous picture has illustrated the souvenir.

On the wall are fixed the two principal clocks, regulated to the hundredth of a second, which were ordered by M. Baillard, the eminent director of the Observatory from M. Leroy, the well-known chronometer maker of the French navy. It is these two clocks which twice every twenty-four hours, that is, at 11 a.m. and at midnight, will signal the time to the four points of the compass by means of the electric apparatus of the Tower. The Transmission of the Hour. Shortly before the decisive moment (ex-

actly at 10.59 a.m. and at 11.59 p.m.) the astronomer on duty, with one eye on the telescope, watches the hand of the clock, and sends the first electric signals to the wireless telegraph station of the Champ-de-Mars. From there, immediately transmitted by radio-telegraphy, they travel immense distances, warning navigators and other wireless stations. Then exactly at the hour and twice again at intervals of two minutes, the clockwork automatically establishes a contact, by means of which an electric manipulator in the Eiffel Tower sets up a discharge of Hertzian waves. And these waves, spreading through space, reach the limits of the immense circle of which the tower is the centre, influencing all the receivers in this area, and conveying to all, as it were, the beat of a heart which is felt in the pulsations of the remotest arteries. A wonderful result, which impresses even the least reflective when they realise this power of instant and direct communication between human beings scattered all over the surface of the . globe.

As I witnessed this simple operation of moving a handle and the contact of a pendulum, it recalled to my mind a very impressive souvenir: that of the solemn moment at the funeral of King Edward VII., when at the very moment of the lowering of the Royal coffin into the vault at Windsor, all work was stopped throughout the extent of the vast British Empire, and it seemed as if, at a signal, the pulse of an entire nation had for some seconds ceased to beat!

And radio-telegraphy performs this miracle every day!

At the Champs-de-Mars.

Here the military authorities hold absolute sway. The transmission of the time is one of the many functions of this important station. Directed with great ability by Major Fender, assisted by several distinguished officers, it keeps Paris in touch with the frontier and even with remote posts in Africa. In fact, it was the great service rendered by wireless telegraphy during the French expedition to Morocco which led to the military wireless telegraphy corps being given its present improved, quarters to replace the shed in the Champs-de-Mars which it had occupied from 1902 to 19.08. The new quarters are connected up with the antennae on the summit of the tower by a special wire.

These quarters are all underground and their entrance, situated about a hundred metres from the Tower, leads to the principal laboratory. It is here that the engineer, officers and sergeants carry out their daily experiments, by the aid of an equipment which is being perfected every day.

On one door may be read the impressive words: “Danger to life.” An officer explained to me that it led to the first battery, which has already been in operation for several years. It gives upwards of 50,000 volts and a range of 2500 kilometers.

“We have another in the new laboratory,” added my informant, “which was only .recently installed, and which the President of the Republic came to see about three weeks ago. This enables us to get 100,000 volts, and we think we shall be able to double our range of action.”

The Range of Communications. “Do you know how far it can carry now I asked. “We are not exactly certain yet. We learn the range only gradually by reports from vessels navigating distant seas. We are already in touch with some of our farthest stations in Africa, That at Dakar, for instance. Communication is not yet perfect as regards transmission to regions where atmospheric phenomena are of much greater intensity than with us. But many messages are distinctly perceived,”

“Do you communicate with the American coast?”

“We receive and register the waves sent from the Lake Bay station, which has at its service a force of 500 horse-power; and we believe that, with considerable less energy, we shall be able to send our waves over there. But it is not enough to talk what is said must be listened to. And, according to international conventions, only the small stations of the Marconi wireless telegraphy system are bound to listen and to answer; the large stations are under the same obligation in regard to distress signals, which they are bound to receive and to transmit. But questions are to be put officially in regard to this matter and will certainly be answered in a satisfactory way so as to enable us to exchange direct communications with the United States and Canada.”

“Your service is gaining daily in importance and extent. And thus the longevity of the Eiffel Tower is assured in spite of the ill-humour of the administration of the city of Paris, which on several occasions has manifested its desire to rid the capital of an unaesthetic and cumbrous monument

“Yes, but superior considerations will undoubtedly override considerations of art.” i

“It is certain that its noon cannon, from the point of view of public utility, constituted an insufficient argument.” “Oh,” said the official, laughing, “that cannon is no more military than it is chronometric. It is simply fired during the fine season by an employee of the tower, who, with the aid of a glass, watches the dial of the Lyons railway station and fires off his petard when it marks midday in order to remind Parisians that it is the time for dejeuner. It may be hygienic; it is in no way scientific.”

“And, since hygiene and science are fitted to agree,” I replied, “let us note that it is noon, the cannon has remained silent, but the breakfast hour has struck in our empty stomachs. Au revoir, messieurs et mercil ”