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Aviation History
1914
1914 - 0815.PDF
II. |*fth»;Ml|<MiWi;ii> JOL\ 31, 1914. I/Sll THE DONATH SIGNAL MIRROR. A METHOD of visual signalling in broad daylight by electricity has been recently introduced by Professor Donath of Berlin. The principle upon which it is based is that at extremely high tem peratures the light transmitted from incandescent lamps is greatly augmented, without a corresponding increase in the consumption of current. In consequence thereof, however, the life of the lamps is much diminished ; but as, in signalling, the duration of a flash is so short, this consideration is entirely negligible, as many messages fitted with a special filament, and is so designed that the lamp can be adjusted axially imide the parabolic mirror, as may be required in order to transmit a parallel beam of light. The mirror and lamp are carried on a handle which is held by the signaller, the switch controlling" the supply ol current to the bulb being mounted on the handle. Above the top of the lamp is a sighting tube through which the signaller observes the point with which he desires to communicate, and by depressing the button on the From the Scientific America n. On the left, an observer in an aeroplane is shown in the act of transmitting a message to the ground, and on the right an observer is seen reading a message, while a signaller is standing by ready to reply thereto. can be transmitted before renewal of a lamp becomes necessary, It is stated by the Scientific American that the full equipment necessary for signalling by this means, including a battery for the supply of electric current, weighs only 11 lbs., and hence the device is especially adapted for use on aeroplanes and airships. The signal mirror itself, which is similar in appearance to that used in the motor headlight, contains a small incandescent bulb ® ® Aeronautical Society of Great Britain. IT is officially announced that the date of the Associate Fellowship Election has been postponed until the middle of September, in order that candidates may be able to take advantage of the second part of Rule 28 with regard to payment of sub scriptions. lamp handle he may send out flashes of varying duration—a shdrt flash (say) of two seconds corresponding to a dot and a longer one, of about six seconds, to a dash. Thus, by the adoption of some conventional system or code, such as the Morse alphabet, communication with distant points can readily be made. Under normal conditions, it is said that signals may be transmitted over a distance of about four miles. ® ® The Trans-Atlantic Flight. THE several alterations to the Curtiss flying boat " America," including the fitting of a third engine, not giving the required results, it is announced from Hammondsport, N.Y., that the hull is to be rebuilt. The attempt to cross the Atlantic is, therefore, postponed to October. Recently Mr. Prosser had occasion to visit the Austin Motor Co.'s works at Northfield, Birmingham, when he required some work done to his engine, and he adopted the plan of making bis call uia the air. Our photograph shows Mr, Edwin Prosser in the pilot's seat of his biplane soon after landing in the field adjoining the Austin works, the extent of which may be gauged from the enormous range of buildings seen in the picture, 815
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