THE EYES OF WAR

Dominion, Volume 9, Issue 2707, 29 February 1916, Page 8

THE EYES OF WAR

WHERE BRITISH MAKERS EXCEI HUGE OUTPUT OF FIELD GLASSES (By T. Thornc Baker in the London "Daily Mail.") The science of sight has been one of the most notable features of the war. That every bullet "should find its billet" is one of the essential things in modern warfare: but with the artillery of to-day, the long distances through which shells can be propelled before they explode, and the submarine's torpedo, a veritable second sight has becqme necessary, and the human eye unaided would be Quite incapable of dealing with tiie problems of attaching from a distance. In one factory alone in Great Britain over a thousand men are employed in 'making range-finders. In other cases factories which before the war were engaged exclusively in making microscopes, telescopes, and instruments for investigating the minute and the vast things of nature, are now devoting their entire attention to making optical instruments necessary for the direction of explosives upon the objects to be destroyed. Manufacturers in this country who made in a year a few hundred field-glasses and opera-glasses for sport or pleasure are now turning out in the same time between thirty and forty thousand military prismatic glasses for the Army. So great is the need of these glasses that they cannot now be bought or sold without permission. Only a very short time ago it' was quite the vogue in Great Britain to buy Gorman field-glasses, German photographic lenses, and German microscopes; they were "indispensable" to the serious man. Now we have discovered that British instruments are as good, if not better, and that many of tho finest, modern optica] instruments are actually British inventions. Submarine's Periscope. Take as an example the submarine periscope, the invention of an Irish lihysicist. Sir Howard Grubb. The ' eye" of every German submarine is a copy of his invention; in other words, enemy submarines find their prey ivith British eyes—they would be blind othervise. _ The artillery range-finder is another instance. Large numbers ,of the British instruments were purchased before the war, and are in use by the enemy; their extraordinary perfection has caused them to be used almost exclusively in the ITrench Army, too. The Turkish array are using British field-glasses in very large numbers. >et until the war—and even up to the present—the idea was very prevalent among tho British that what are known ns "precision instruments" in the optical way must be of German origin if lliey are really of any use. A great new industry has been (established in our country through the war, and already British opticians have established the fact that thoy stand pre-eminent in a vast branch of manufacture hitherto allied in popular opinion as much with Germany as is the aniline dye industry.

There have been difficulties to contend with which cannot be laid to tho blame of any lack of foresight in this coimtry, such, as the scarcity of certain types of glass. A very dense typo of Hint glass, for example, is used in tho manufacture of prims; locality plays an important part in the nature of the ra.iv material, and most of this glass came from Jena. It is being made both in France and .England in increasing quantities, but in tho meantime our soldiers have had to use trench periscopes made for only one eye in order to conserve the supply, of prismatic glass, whereas the German periscopes are binocular. There have been amusing instances of tho effcct of this shortage of glass in industrial work. One firm, for example, >vere about to place a new pill on tho market. Thousands of pills were manufactured, but no suitable bottles could be obtained, and the pills aro still waiting for .the war to end.- In another case a face cream had been supplied in tasteful opalescent glass jars. New jars were wanted, but none -could be got, and the cream had to be put up in very ordinary common glass pots. A great deal of anxious work had to be done by the travellers of the firm ,in question to convince grumbling -customers that the cream, despite 'its less aristocratic outward appearance, still maintained its inherent good qualities. Yet another instance is tliat of a brewing firm, anxious to introduce some new beer with some notable qualities; here war intervened in the form of a scarcity of screw-stop-pered beer bottles. Beer devotees in the South of England insist on their beer being delivered in screw-stoppered bottles —they will have none of the por-celain-topped, spring-stoppered bottle, which is much more abundant. Henco the new beer is also awaiting the end of the war.

To return to the prism, however, it may bo surprising to learn what an important part his plays in means of sighting in warfare. Trench periscopes, ritle anil 'other telescopic sights,' prism binoculars, range-finders, nearly every typo of instrument, takes advantage"of the reflection without appreciable loss of light which a prism, as distinguished from an ordinary mirror, will give. The use of a prism also enables the human eye to he placed at a lower level than the "eye" of the instrument, which means a great saving of human life. The now almost universal telescopic rifle sights not enly bring the enemy visibly much nearer, but the soldier is able with them to see what he could not see witli the naked eye unless he held his head an inch or two higher above the trench. Rangß-finder9. Tins men working a gun to-day are very nuich like the engineers in a ship: ooeying commands without seeing where i.hey are going or what exactly they are doing. The range of the enemy is found by means of a range-finder. Simply described, this instrument comprises two telescopes about tlii'eo feet it part, one of which throws an erect image on an eyepiece near the middle <if tne instrument: the other an inverted image. A dolicato adjusting screw Is turned until the erect image comes exactly above the "upside down" image, when the range can be read off up to ten or fifteen thousands yards on a scale. The gun is trained, following on these details, by artillery officers, allowance being made for the continual falling of the shell during its (light through the air, and the men who actually fire the gun are mere automatons, acting as the mechanics who ieed and drive the engine of destruction.

British opticians, as already stated, riband pre-eminent in tlio malting of range-finders, although a German instrument is included in the official artillery text-book, and was used by our Amy for many years. Hlucli might- be written of British inventions in the science of sight which seems to border on the miraculous. There ts a little instrument known as the corner-cube prism which, if fitted to a vessel at sea, makes that vessel distinguishable from any other by those on shore who have the necessary sighting apparatus, though the ship may be miles away. This little instrument, hardly bigger than a lump of sugar, possesses the remarkable power of reflecting back in a "bee line" every ray I of light that is directed upon it, no matter ftom what direction it cninc4< I There arc innumerable instances of in-

genuity in actual use in the war which cannot, for obvious reasons, be described. Jiut a lesson to be learnt from a study of the "eyes" of the Army and iN'avy is that so many of them were originally invented by our own couttErymen, such as the compound photographic leus of to-day, without which we should have none of the thousands of Press photographs which bring the war so much nearer to us. Too little thought has been given to Fliis great British industry, for it is olie of, unhappily, too few in which Great Britain has, all unsuspectingly, led, and maintained its lead of, a world science.