Inventions of the Great War

by A. Russell Bond

HIDING BIG GUNS

Nature's tricks of camouflage were freely used in the hiding of the implements of war on land. Our big guns were concealed by being painted with leopard spots and tiger stripes, the color and nature of the camouflage depending upon the station they were to occupy. In many cases, they were covered with branches of trees or with rope netting overspread with leaves. So careful was the observation of the air scouts that even the grass scorched by the fire of the gun had to be covered with green canvas to prevent betrayal of the position of the gun.

ROADS THAT LED NOWHERE

In the making of an emplacement for a gun it was of the utmost importance that no fresh upturned earth be disclosed to the aërial observers. Even foot-paths leading to it had to be concealed. Plans were carefully made to cover up all traces of the work before the work was begun. Where it was impossible to conceal the paths, they were purposely made to lead well beyond the point where the emplacement was building, and, still further to deceive the enemy, a show of work was sometimes undertaken at the end of the path. Wherever the sod had to be upturned, it was covered over with green canvas. The earth that was removed had to be concealed somewhere and the best place of concealment was found to be some old shell-hole which would hold a great deal of earth without any evidence that would be apparent to an observer in an aëroplane. If no shell-hole were handy, the excavated material had to be hauled for miles before a safe dumping-ground could be found. As far as possible everything was sunk below the earth level. Big pits were dug in which the mortars were placed, or if a shell-hole were empty, this was used instead.

SHADOWLESS BUILDINGS

Any projection above the ground was apt to cast a shadow which would show up on the observer's photographs. This was a difficulty that was experienced in building the hangars for airplanes. The roofs of these sheds were painted green so as to match the sod around them, but as they projected above their surroundings, they cast shadows which made them clearly evident to the enemy. This was overcome by the building of shadowless hangars; that is, hangars with roofs that extended all the way to the ground at such an angle that they would cause no shadow except when the sun was low. In some cases, aëroplanes were housed in underground hangars, the approach to which was concealed by a canvas covering. As for the machines themselves, they scorned the use of camouflage. Paint was little protection to them. Some attempt was made to use transparent wings of cellon, a material similar to celluloid, but this did not prove a success.

THE PHOTOGRAPHIC EYE

Although camoufleurs made perfect imitations of natural objects and surroundings, they were greatly concerned to find that the flying observers could see through their disguises. To the naked eye the landscape would not show the slightest trace of any suspicions object, but by the use of a color-screen to cut out certain rays of light, a big difference would be shown between the real colors of nature and the artist's copies of them. For instance, if a roof painted to look like green grass were viewed through a red color-screen, it would look brown; while the real grass, which apparently was of exactly the same shade as the roof, would look red. It had not been realized by the artists who had never studied the composition of light, that there is a great deal of red in the green light reflected by grass, and that if they were to duplicate this shade of green, they must put a certain amount of red paint in their imitation grass roofs. Air scouts did not depend upon their eyes alone, but used cameras so that they could study their photographs at their leisure and by fitting the cameras with different color-screens, they could analyze the camouflage and undo the patient work of the artist.

A CALL FOR THE PHYSICIST

To meet this situation, another man was summoned to help—the physicist, who looks upon color merely as waves of ether; who can pick a ray of light to pieces just as a chemist can analyze a lump of sugar. Under his expert guidance, colors of nature were imitated so that they would defy detection. Aside from this, the physicist helped to solve the tricks of the enemy's camoufleurs.