ELECTRICAL COMMUNICATION.

Manawatu Herald, Volume L, Issue 40021, 9 November 1929, Page 2

ELECTRICAL COMMUNICATION.

ADDRESS BY MR. D. T. ALLAN AT LUNCH CLUB.

Oil Thursday Mr. D. T. Allan, engineer of the P." and T. Department., Palmerston North, delivered an interesting address to members of the Foxton Lunch 'Club on “Electrical Communication.”

“The study of electrical energy and its conservation,” said Mr. Allan, “teaches us that the world is created as a whole and that man cannot create anything on his own, merely being able to transform one form of "energy to another. lie burns a haystack, it is not eliminated, merely changed. He dams a 5-river and by means of pipes .and machinery he says lie has created electrical energy, but in reality he has only changed the potential energy of the rivet' into hydro-elec-tric energy. AYihen electricity is thus produced it leaves thempower at, say 110,0110 volts, far too high for direct commercial or domestic use and so the electrical engineer erects transformers throughout the district, to break down Hie power, to lower the voltage - and change or transform that energy in order that it might be applied to domestic and commercial uses. The v.iiloe thing is just a changing of one energy to another and this is found to lie so-right throughout the universe.”

Mr. Allan briefly referred to the first primitive means employed by man to convey news from one part of the country to another by means of runners and beacons, and stated that the fill's t discovery in connection with electrical communication was made in 177-1 when it was found that if a certain electrical condition was applied to the end of a w'ire a certain condition obtained at the other end which led those investigating the method to believe that electrical eurreijt flowed along a wire, a belief later exploded by fuller explanations as to what electricity actually was. In 18J74M.oir.so first used;a code in combination with electrical energy, to transmit messages from one. place to another. This first code consisted of five characters which were printed on a tape, read and translated. Thus method was soon found to be too slow and men were trained to read the messages !iy sound and to- write down the translated message. Further improvements were then effected which enabled two messages to be sent over the one wire at the same time without interfering with the clarity of each individual message and this was considered a great advancement in electrical communication and the wonder of the age, hut only a short: while elapsed betoro four messages were being sent over a single' 'wire at once and a printing system was invented whereby the messages were punched out on paper which enabled them to he transmitted and received at a great rate thus effecting a great economy in line time. Then came the telegraphic. typist who operated a highly efficient and very accurate machine." The message was typed out on a machine similar in appearance to a typewriter hut which also transmitted the message and it was received at the other end typewritten and addressed ’readv to leave the Post Office. Sufficient time elapsed between the typing of the message and the actual traifsmissiou to allow an operator to correct any error lie may have made prior to the message being despatched so that the telegram was always received correct, in every detail at the other end. In the United States to-dav the large hotels and business linns adopted similar methods in dealing with their guests or clients. When person entered the hotel lie approached the office'where he gave details as to his name, address and duration of stay to a. clerk who typed the particulars out and as he was doing so a tape hearing the particulars was tunning out of a machine on the floor to which the guest was being despatched so that on his arrival there the attendant knew who he was and all about him. In the big manufacturing concerns of the States the machine also played an important role. A client came in with an order. It’was taken down on the machine and at the same time particulars of the order were being received in every department with which it was'concerned. The details as to materials required were being ircceived in the material department while the manufacturing and packing departments would also be receiving the message hud so each department got to work on the order at the same time and a great deal of time was saved.

' “Despite these wonderful inventions in connection with telegraphic communication,” said Mr. Allan, “it is the dying' side of electri- < al transmission or communication. Telephony is rapidly replacing' it,” and in dealing- with this side of his subject, the speaker briefly outlined the progress of. the telephone iit an intesesting jammer. He’ re i'erred to the first crude telephones' of Reece and Graham. Bell and of the. discovery-of the microphone by Edison which revolutionised telephonic transmission of speech. With the application of the telephone to social, domestic and -business life it was necessary for those associated with this mode of transmission not only to be engineers hut also to become scientists. The (human sight- and hearing had to be closely studied. The ear had to be carefully considered if transmitter and receiver were to function perfectly. Hearing was made possible by air vibrations acting on the drum of that organ and in a great many ways the ordinary telephone was a replica of the human

ear. M the transmitting end of the telephone the vocal cords of the speaker set up vibrations which were caught on a metal diaphragm which varied the pressure on granules of carbon which in turn varied .the electrical pressure or current which sent the vibrations along the wire. In other words at the transmitter end the air waves were converted or transformed into electrical waves. At the receiving end it was necessary to convert the electrical waves hack to air waves in order that they might act on the ear drum of the receiver. An electro magnet varied the pull on the diaphragm in this instance and so set up air vibrations which were readily translated by the human brain per medium of the ear. The operation was instantaneous. Electricity travelled at a ‘ far greater rate than air waves and a person speaking over the ’phone to Auckland would actually he heard by the person in Auckland before n per - son standing at the other end of the room in which the telephone was would hear the speaker’s voiee. Peculiarly enough, said the speaker, the great advances in the art of electrical transmission have been due to scientific discoveries into the secrets of the Universe. The astronomer and the scientist with his microscope have both: contributed in a great degree towards our present day transmission system. The laws governing the solar system strangely enough, apply to the infinitesimal electron, the basis <T all matter and energy, and from the discoveries made in connection with electronic action the scientists have been able to produce the vacuum tube from which the greatest advancement has been made in electrical communication.

themselves. Dealing with the transmission wires the speaker said that the messages were at first sent over a single., or earthworking wire which was soon replaced by tlig more effective metallic circuit, or two wires. The discovery was then made that telegraphic communication over these wires did not interfere with speech and so both methods of -transmission were sent aver the wires. Farther experiments were responsible for the discovery of the phantom circuit which meant that three transmissions could !be made over the wires, while quite recently the speaker had been engaged in the installation at Palmerston North of Hie most modern development in transmission to date, the carrier system by means' of which a multiplicity of messages could be carried on the circuit without interfering with each other. In all sixteen persons could work on the one eirsuit at the same time by this means without any 'of them interfering with the other. The'discovery was due to the introduction of radio principles to telephonic circuits. If four persons were using the line atthe one time, the four speecheswere brought into the equipment, ve.-energised and then sent out on different frequencies or waves. At the other end the waves were picked up and passed through a filter which separated thp various speeches into their right channels' These filters,, 'which Mr. Allan likened to Hie metal sorter on a stone crusher, were 1 so adjusted that they picked up only the messages intended for them and rejected any others which passed on to their correct channels. In conclusion, Mr.* Allan said that although great improvements had been effected in transmission in recent years, we were now on the edge of greater developments which would revolutionise the whole system. He referred to the introduction of the Talkies, the greatest development of recent times, and said that in Germany to-day they were perfecting a machine which would enable a person to remain at home and both see and hear operas and (other functions in the comfort of one’s own home. Television, he concluded, was not a thing to he looked forward to in fifty years time. It was here now.