SUBMARINE’S EYE.

Manawatu Herald, Volume XXXVII, Issue 1364, 20 February 1915, Page 4

SUBMARINE’S EYE.

In both submersibles and sub marines there is a difficulty of so discharging their torpedoes as to make striking an object a fair certainty, and much ingenuity has been directed to obtaining a satisfactory instrument of vision for use when the vessel is in a steady position somewhat below the surface of the water, and that most generally used is a “periscope,” or “optical tube.” A iot"l reflection prism at the upper end of a telescopic tube is placed -bov- the water, with a similar rism at the lower eud of the same ”ibe which reflects on a table in .be conning-tower, and'enables an observer to see over a limited distance the objects in his neighbour•nd. If the top of the periscope L c submerged, nothing, of course, can be seen; but for strategic purposes a submarine would seldom dive deep enough to submerse her optical lube. The periscope is ? very minute object, and even when the boat is running at her full submerged speed the movement of this tube through the water, its top only a few inches above the surface, makes so trifling a commotion as to be in(.ltsgiuguishable in anything but a perfect calm at more than 500 yards.