New Range Finder.

New York Times 100 years ago today, July 13, 1913:
Inventor Disgusted with British Admiralty, Will Sell It.
    LONDON, July 5.— After experimenting for five years with a range finder invented by A. Hungerford Pollen, the British Admiralty has decided not to adopt it for the British Navy. The inventor has therefore patented the apparatus, and will seek to dispose of it to some foreign nation.
    The Naval Annual, in commenting on the subject, says that it is at a loss to account for the decision of the Admiralty, as experiments had proved the range finder to be the only accurate one in existence. The apparatus is based on the paradox that if two ships are approaching each other at a combined speed of fifty knots, and the first shot be fired at a range of 10,000 yards, the range would have to be altered by nearly half a mile while a 6-inch projectile is in the air.
    It was, therefore, not only the absence of a range finder that accounted for the short distance at which naval firing was being carried out, but because no one had yet solved the problem of how to ascertain the future position of the moving target and to lay and train the guns accordingly. The conclusions at which Mr. Pollen arrived were, first, that the only clue to the future position of the target must be found in its past movements; secondly, that the only conceivable information of its past movements that could be obtained must be the observation of its successive previous positions; thirdly, that if these were plotted, with due allowance for the progress of the observer's ship through the water, a plan would result; and fourthly, that from such a plan the forecasting of the future ranges and the angle of deflection must be a mere matter of calculation.
    From these conclusions Mr. Pollen went to work, and ultimately devised a method of ascertaining the target's speed and course that is almost automatic. He has also devised a change of range machine for automatically supplying a forecast of the ranges to the guns. This machine not only generates the future ranges and bearings of the target at the true rate of change, but, like his plotting table, can be corrected for any change of course by the observer's own ship.