The Zeppelin's Doom

Pukekohe & Waiuku Times, Volume 5, Issue 138, 28 January 1916, Page 1 (Supplement)

The Zeppelin's Doom

ALLIES' ELECTRICA No longer do German airships und'T. j tttKe raids over the territories oi their , western adversaries during daytime and m clear weather. The dirigible pilots Know too well the vulnerability of their Huge craft to the hurricane of fire from thousands of anti-aircraft guns that dot Fiance from the wavy western battle line to, Paris, as well as those that guard the coasts and interior points of England. And the danger to them is aot confined to anti-aircraft guns, for mere are the squadrons of fast, heav-ny-armi'd battle aeroplanes to contend with, which rise in virtual swarms to Kive battle to the more cumbersome oir cruiser.

The onening month of the war witnessed tlie utisuccesstul and somewhat costly efforts of the Teutons to employ their Zeppelins in daylight for tne Oombardment of fortresses, camps, and cues, and as participants in military engagements. The second month, Scptcmrjer, saw the practically total abandonment of daytime raids on the western iront the German pilots evidently uaving decided that their air cruisers could be used to far better advantage una with almost complete immunity from gun fire and aeroplane attack irnen employed at n'ght, in foggy weatner, or when low-hanging clouds off?r aa effective screen behind wnich Zcppcuns can navigate without being observed.

The protection that airship mints Hiwe thus availed themselves of is but a temporary respite, for, altiv.) igh tlio eruft may be invisible to ot>«t«".\s en sne ground they are not noiseless, the sounds of tlie engines and propeller Mades can be detected and amplified with suitable devices, serving to betray the presence of an airship; and (says a writer in tne "Scientific American") developing these systems to a still finer aegree, it lias been rendered possible uvea to determine the range of the unseen airship for setting the fuses of the anti-aircraft shells and adjusting the aerial guns.

THE FRENCH DEVICE. The anti-aircraft defenders of Paris nave devised an ingenious arship detector which they call a poste d'ecoutc, 01 listening station. It is in tne form ol four huge horns or reverted imyaptiones so mounted as to swing on a pivot to any point of tiie compass and luru on bearings to any angle in relation to the ground. The horns all point in the same direction, and because of their huge size as capable of gathering the slightest sounds. These are then magnified by means of niicropnones. An operator, swinging tho liorns m all directions and listening carefully to the sounds gathered by the device, can detect the presence of an airship at a considerable distance away, even if it be high in tho air and nehind dense cloud banks. It is also possible to determine the approximate position of the invader and despatch a squadron of aerial defenders to rise among the clouds and give battle to him after he has been found. Whereas the French airship-detector only serves to betray the approach of hostile aircraft, there has been developed in the United States a system for detecting as well as determining tho

exact portion of hostile airships, making it possible to furnish anti-aircraft gunners with the range of the invisible target. The system, which makes use of telephone microphones in an ingenious manner, the invention of Edward K. Chandler, of New York, whose work in torpedo design has been extensive.

This airship detecting system consists essentially of placing telephone microphones at the corners of a geometrical figure which may be in the form of a triangle or a parallelogram of known size, and adjusting these microphones until the sound waves from the aircraft are loudest; the microphones then aiming towards a common point which is the position of the airship. .Mathematical calculations thou permit the determination of the distance between the common point, or Apex, and the ground, giving the range to the gunners.

FOIt FIELD PURPOSES. In its simplest form, and that which will be used in temporary installations <n the field, each microphone is placed lit the base of a large horn, which in rum is mounted by means or a gimbalring construction similar to the mounting of marine compasses—on a fieavy service tripod. A microphone is placed at each corner of an imaginary triangle or parallelogram of known 'size, and an operator detailed to each jioerophone. The operator, wearing a telephone headset, slowly moves the horn about in ali directions until sound rt-aves caused by airships are detected. The horn is then adjusted until it points straight at the source, of the *ound wave-, which is determined by the loudness of the sounds. As the a rcraf't moves the horn is also moved, nnd when the target passes within effective range each operator—who in the

I. RANGE- FINDERS. meantime lia.s boon adjusting his uiicro(itiono, so that they nil point towards a common centre —signals the readings of his instrument to the gun pointer, liy combuv.ng the different angles and dil cottons at which the microphones arc puinted, the gun pointer can arrive at the apex of an imaginary pyramid or cone, and it is then but a simple mathematical problem to determine the distance between the apex and the ground, which is the range sought. To facilitate the calculations, u special lurm of slide rule is employed so that the determination of the range is greatly simplified and occupies but little time.

in installations of a permanent character, such as those for the protection or fortresses and cities, the detector system is more elaborate and necessarily more complicated. The essential principle remains the same : the microphones are mounted at the corners of nn imaginary triangle or parallelogram of known size. However, this system requires but one operator, who is located at some suitable point which may oc remote to the zone of the detector system if desired. The microphones ere governed by the operator through a remote control system which make* sse of differential resistances and magneto, and is similar in principle to the Gray telautograph mechanism which transmits facsimile handwriting over wires.

The operator listens by means of tho telephone receivers worn on his head to the sound waves striking each miorof>none; the microphones being constanty turned in all directions so as to cover the sky that cornea within th» aone of the installation. When the sounds of an airship are picked up. the/ microphones are each adjusted until tho sound is loudest in the telephones.

HOW THE SYSTEM WORKS. After the sounds of an airship have !>een picked up on each microphone of the system the operator switches the sound detectors on to the galvanometer device, and makes the final adjustments of the microphones, carefully watching the needles until they both point to 0 and towards each other. This, then, indicates that, each micropnone is equally affected by the sound waves, and accordingly pointing towards their source, which is the target sought. An instant's work with a slide ru;e results in determining the distance oetween the apex of the imaginary cone or pyramid formed b.y the known distances between the mic!optionee and the direction in which they are pointing towards the common point and the ground. This information is then telepnoned to the anti-aircraft artillery, as well us to the aeroplane squadron commander, if so desired. Since aerial artillery does not require the exactitude demanded by military and naval range finding, the distance of the target from the ground is sufficient for the determination of the range. The shells are usually in the nature of shrapnel, and upon exploding scatter fragments over a wide area, bo that the main requirement is to time the fuse of each shell so that the explosion will occur on the same level and as near to the airship as possible The microphones, in conjunction with suitable amplifying apparatus, are capable of picking up airship sounds several miles distant, and while the operator then adjusts his microphones to point towards the moving target—using oniy one or two microphones fortius purpose, since there us no object tobe gained in using the others at tlrs time —he makes no attempt towards tlie final adjustments until the airship. passes within the effective zone of the installation. The microphones follow the moving target much in the same manner as a pair of eyes; a skilled operator being able to move them in perfect unison. There is no hard an.) Hint rule for the most suitable shap>.« and size of base figures to use with tin* system. The microphone* can be spaced several hundred yards apart; and the inventor stativ that lor determining ranges up to 5001) feet, a spacing fii tfOO yards between microphones & lucai.

A LONDON SCHEME. Recently, Dr. Lee Do Forest, perhaps best known as the inventor of tho nudion wireless detector, the audion amplifier, and the audion high fn - oiu-ncy generator, left New York lor England on the mission of installing nn alrsiiip detector system for the protection of London against Zeppelin raid". As far as can be learned at the present moment, the De Forest system also makes use of a number of microphone!* placed in a geometrical figure on tin* ground. The audion amplifier is employed to magnify the toecived sound waves and thus increase the range of the apparatus. By adjusting the different microphones so as to obtain tbo loudest sound from each, the microphones point towards a common p<> nt, which is the apex of a cone, and mako it possible to calculate the targets Tango.