ACCURATE SHOOTING MADE EASY.

Star (Christchurch), Issue 7203, 14 September 1901, Page 3

ACCURATE SHOOTING MADE EASY.

The reports of the inadequate results obtained in South, Africa from the expenditure of immense quantities of ammunition, led Sir Howard G-rubb, of Dublin ; .whose rame, says " Engineering," is known, to all by reason of the fine optical work he iias done -for astronomical purposes, to endeavour to utilise the methods of the physicist for the benefit of the rifleman: and the artillerist. ,The conditions are not unlike. Wh«n in the laboratof^the' spot oft light of a galvanometer 'is brought' im to the zero of the scale, it is certain that ih? mirror of the instrument points directly at the same spot. On the battlefield the enemy's line is the scale, and thp particular man- the marksman wants to hit is the zero point. If he had some means of projecting a bright image on to the man from a mirror filed in definite relation to the 1 barrel of bis gun; and if, moreover, the bright object sent parallel rays to his eye, the action of aiming would be retfdefe'd. vastly^ easier. How this caw be done- "willfbe unVr <lerstood from the following explanation;. On a small sheet of glass, inclined; to the sky, is engraved, a cross. The light rays from this cross radiate in all directions, but a portion of them fall on a silvered . surface at the lower part of an inclined Bheet of glass, and are reflected on to a concave glass at the front of the apparatus. The surface of this glass is reflective, and sends the rays back towards the eye of the marksman. The radius of the glass is such that it renders the divergent beam parallel, and produces what is called a "virtual image " ; that is, the eye sees the image . of the cross as .if it were 4 long distance in front of the. instrument. The image is not reducedSn size and brilliancy as if it were at a distance, but yet it can be focussed on the retina without any effort, *long- with objects that are hundreds of yards distant. It is like a foresight carried on the end of a pole attached to the barrel. Evidently if the barrel could be so far extended that the marksman could plant his foresight on the chest of his enemy, there would ba no need of a backsight at all ; and this is exactly what is done by Sir Howard Grubb's device, except that an imponderable beam of light carries the image of the sight in place of the actual thing itself.