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M.I.7b(4), 12th March 1918
1. By Aeroplane. Without doubt the aeroplane is the most efficient and simplest, but on account of the action taken by the Germans on the Western Front in court-martialing and sentencing captured airmen, its use has been stopped by order of the C-in-C.
There are two ways of using it:
(a) With wind driftage. Single leaflets thrown out from an aeroplane at a height of from 5,000 to 10,000 feet will drift from ten miles upwards before reaching the ground. In suitable winds therefore leaflets may be thrown out loose from aeroplanes flying parallel to the enemy lines at a distance of several miles from these lines, according to the strength of the wind.
(b) When the aeroplanes fly over the enemy lines, the matter to be dropped, unless it consists of relatively heavy pamphlets, should be tied in bundles which will disperse only when they have nearly reached the ground. Individual leaflets should be folded in the method described under balloon distribution.
2. By Kites & Carriers. This method is quite effective for ranges of from fifteen to twenty miles according to the strength of the wind. It has been turned down on the Western Front because of the incessant aeroplane activity, as the wire of the kite is a danger to aeroplanes.
The method requires box kites weighing from 7 to 10 lbs. each and costing (as supplied by Messrs. Gamage in small quantities) from 75 shillings to £6 each. These can be sent up in a light to strong wind by two men where there is a stretch of from 20 to 100 yards free ground available. The kites are attached to a wire cable paid off a winch. Light power winches with suitable brakes such as are used by the Naval Meteorological Department are required. The kite can be used for liberating propaganda as soon as it has reached a sufficient height, which in the experiments was found to be from 3,000 feet upwards, nearly 10,000 being attained. The propaganda is sent up by Gamage’s Automatic Kite Conveyer, a hinged framework of canvas with spread of about fourteen square feet. This is mounted on a runner which passes up the cable leading to the kite on grooved wheels. The runner has a trigger device and when the Conveyer has been taken by the wind up to a stop fixed on the cable near the kite, the trigger comes into action, releases the propaganda sheets and folds down the wings of the messenger. The Conveyer or Messenger then comes down again, is received on a string buffer and can be recharged with propaganda and sent up again. Each conveyer, as supplied by Messrs. Gamage in small numbers, costs £4.4s. The inventor estimated that loads of fifteen lbs. could be taken up; in the actual experiments, in light winds, loads of five to seven lbs. were found quite easy to take up. The messenger takes several minutes to attain an elevation of 4,000 feet and rather less to come down. In a very moderate wind, propaganda sheets liberated at a height of about 4,000 feet were picked up on the ground ten miles away.
There is no reason why this apparatus should not be employed in the dark.
3. By Balloons. For some time experiments have been made with balloon distribution as other methods were considered impracticable on the Western Front. As the smallest useful size of fabric balloon costs between £8 and £10, experiments have been conducted with paper balloons and a satisfactory type, costing with the propaganda release about 13s. each has been arrived at and is being manufactured so as to give a weekly output of 1,200 for the Western Front. These balloons carry a load of 2 lbs. of propaganda and are useful for distribution up to a range of about 20 miles from the liberation point. Experiments with balloons to carry a larger load for the same range of distribution are in progress, but in practice paper balloons are so fragile to fill and discharge that it is expected that the limit of useful capacity will not be much more than three or four pounds.
The type now being made and used with success is made of sections of doped white paper pasted at the edges and with a short tubular mouthpiece of oiled silk. The mouthpiece is provided with a string which ties it up after inflation. Supporting strings to carry the load are attached to the balloon by strips of gummed paper. The balloons are circular in section in the horizontal plane and the height is about one and a half times the diameter. The circumference at the centre is 20 feet and the height ten feet.
The "Release" (which has been settled after experiment with many different types) consists of a board 9 inches long by 4½ wide to which the fuse is attached. The fuse is a piece of orange-coloured tinder similar to that used in pipe-lighters and burns at the rate of one inch in five minutes as attached to the board and in the open air. It is arranged in a rectangular spiral, beginning at one corner on the outer edge and finishing in a straight piece about five inches long along the centre of the board. 28 inches of fuse are used. The board is slung to the supporting strings of the balloon by slings attached to its corners and has the fuse uppermost.
The propaganda is attached to the central or terminal part of the fuse in 8 bundles of four ounces each. The attachment is by threads which pass through the fuse and through holes in the board. The threads are half an inch apart so that the bundles are released successively at intervals of 2½ minutes.
The part of the fuse from the outer corner to the attachment of the thread for the first bundle is arranged to regulate the distance to which the balloon will travel before beginning to release the propaganda. It is marked off in inches by figures stencilled on the board, from 24 to 1. When the fuse is lighted at figure 24 it will burn for two hours before beginning to drop the load; when lighted at other figures for a proportionately less time, the piece of fuse in front of the lighting point burning away harmlessly. Obviously the distance that will actually be traversed depends on the place where the fuse is lighted and on the speed of the wind, and simple tables working out these calculations have been drawn up.
As the object of the paper balloon distribution is to reach a definite area and then to drop the propaganda within it, it has been found useful both by us and by the Germans, to fold the sheets in a particular fashion. Each sheet should have the length to the width in the proportion of five to four; it is then folded as in the sample attached, and suspended in bundles by a thread passed through a punched hole. Heavier folded matter can also be attached in the same way. For inflating and liberating the balloons, some kind of shelter is required to protect the balloon from gusts of wind. A screen in three panels, formed of canvas fixed on poles has been found useful. The side panels should be about 25 feet long, the back panel fifteen feet long and all three fourteen to sixteen feet high. The screen should be set up with its open end pointing in the direction to which the wind is going.
Hydrogen is used for inflating the balloons. The balloon is laid at full length but folded on the ground with its mouth towards the open end of the screen and its top close to the back of the screen. The mouth is placed over the pipe leading from the nozzle of the hydrogen cylinder and the gas turned on slowly. The balloon is inflated to about two-thirds of its cubical capacity during which time it gradually rises and has to be steadied by the supporting strings. The release with the propaganda is attached to the supporting strings at the points where these are tied together. The nozzle is removed and the mouth of the balloon is tied up and the fuse lighted at the point indicated by the directing officer. As soon as possible after the lighting the balloon is released, care being taken to see that all the strings and the release are clear. As the balloon rises it expands and becomes quite taut; if filled too full it would burst soon after ascending.
4. Rockets, Projectiles, etc. Various forms of these have been considered, but hitherto have been rejected, for military reasons on the Western Front. They have all a very limited range. The French have experimented with various forms of projectile containing propaganda wrapped inside a metal case, and provided with a detonator worked by a time fuse. One form of these is fired from a V.B. grenade discharger from a rifle, by means of a blank cartridge. It lets loose the leaflets at a range of 200 to 250 yards at a height of 100 to 200 feet. Others fired from 75mm field gun burst at a range of about 1,400 yards. It is believed that distribution at short range would seldom be useful, as the men whom the propaganda might reach are otherwise occupied.