THE MAGIC SPARK.

Auckland Star, Volume LV, Issue 115, 16 May 1924, Page 9

THE MAGIC SPARK.

ELECTRONS SIMPLY | EXPLAINED. I THEIK STRANGE BEHAVIOUR. Tll£ MARCONI BEAM. DIRECTIONAL AERIALS. 1U PHOKOS. Leading-tplpgTaphist L. R. Flood, of! HM.s. Hood. having completed his period of service in tie Navy, leaves tiie j warship at Auckland to enter the com- j mercinl radio world here. It is rather a sore point in the wireless branch of the Navy that their j operaturs. though highly efficient, and j poi.'f.-'siiig the British P.l\|.G.'s certi- j ficate as operators, receive rather a j set-hack when they endeavour to secure | post* in Hip merchant, service. After '. all their years of work and training, j the Marconi Company insists on their I taking a special course at one of the ! training depots, and then offers I merely a junior operator's job. It is ! bard on the ratings, certainly, but it is | good for the Navy, for, through this, the ' most experienced hands stay with the fleet instead of drifting to the mercantile marine. Dr. Buist, the Hawera enthusiast, writes that he has just assembled a five-valve Freed-Eiseinann neutrodvne from bought parts, and is very keen on its receiving qualities. He gets Sydney j at L.S. strength on the stage of audio, while on two stages the row is so tcrri- I fie as to he unpleasant. i The "Sleeper Monotrol,'" a set that has : not yet made its appearance in the Dominion, is exciting much interest in other .parts. It utilises the Grimes inverse reflex principle, and is a fourvalve apparatus. three of the valves being reflexed and the fourth used as a straight-out power amplifier. Due to the utlisation of this reflex principle the set provides the equivalent of an ordinary seven-vavle one. It is adapted for loop aerial only. Aerial Directional Effects. Some aerials receive very much betfer in one direction than in another, and this applies particularly to long low aerials in which tho lead-in is taken from the end of the aerial. Tests have been made recently, and it was found that an aerial not more than 100 fpet in length and not less than 30 feet above the. ground has very little direc- , tional effects. In aeriale where the directional effects are noticeable it usually will be found that the horizontal length is equal to or more than four times 'the vertical height, and in constructing an aerial fan should try to avoid such a condition. Beam Transmission. The cable have given prominence to the recently-developed system of beam transmission which has followed an exhaustive series of experiments conducted by Signor Marconi and others. Recent files from England contain the following particulars; supplied by Marconi himself: — Senator Marconi, who for two years has been experimenting with "beam" transmission, declared that this method will soon be available for long-distance communuication. "By such a beam the waves would go in a straight line from to station," he said. "T.he method will increase the secrecy of wireless messages and give "higher speed in transmission. The cost of operation will also be reduced. I have made successful experiments m sending messages from Cape Verde to Cornwall on a beam, a distance of 2200 miles, and I am about to experiment with beam transmission from England to South America, a distance of about 5000 miles. The Magic of the Electron. The electron is the smallest unit of electricity. With one exception it is the only thing in nature that cannot be broken up into smaller parts. We do not know absolutely its size and shape, but it is generally assumed to be a sphere of such size that if enough of them were laid in a row to make a line as long as the diameter of one of the hairs of your head, it would require more than seventy thousand million of them. In .spite of the minuteness of the electrons, which is really, far beyond the limit of human comprehension, the quantity of electricity associated with it has been measured so accurately that the error cannot be greater than about one part in four thousand—less than four hundredths of 1 per cent. This charge of the electron is, like its size, so small that a figure representing its magnitude is quite meaningless. Some idea, however, may be grasped by computing the number of electrons which are equivalent, in quantity of electricity, to that which flows through an ordinary 40-watt lamp in one second. This is found to be about two and a-half quintillions—2s with 17 cyphers after it. This number is so enormous that if all the .people on the earth—and there are about two thousand millions of them — were put to the task of counting this number, and each man, woman and child counted at the rate of one electron per second for ten hours every day, it -would take over eeventy-five years to finish the job. This is the number of electrons flowing through the filament of a 40-watt lamp in a single second. So much for the electron itself. We shall now consider its connection with the filament in a vacuum tube. It is now known that every atom of every element is made up partly of electrons, and that, at least in metals, there are, in addition to the electrons tied up with each atom, other electrons which are free to move about. These "free" electrons, whether in a metal or outside in space, always move toward a positively charged body and are repelled by a negatively charged one. A current of electricity in a wire is nothing more than the movement of these "free" electrons in the direction of a positive charge. About thirty-four years ago Sir J. J. Thomson discovered that, although electrons could not be drawn out into space from a cold body by the attraction of a positive charge, electrons could be drawn out from a filament when it was heated. This opened the door to the interesting field of thermionies, the emission of electrons 'from hot bodies, and a great deal of work has since been done by other physicists in determining the laws governing this phenomenon. It has been found that the emission of electrons from heated metals is quite analagous to the emission of vapours from heated liquids. The. rate of evaporation from liquids is known to increase very rapidly as the temperature is raised, and the same general law has Veen found to apply in the case of the 'evaporation," if vre may call it such, of electrons from hot bodies. |