A graphic means for determining the distance from a light as it is raised on the horizon
The quest of the navigator for every means of lessening the chances of disaster at sea has led him to devise various methods for obtaining the location of his vessel to meet the varied conditions imposed upon him by the vagaries of the weather. These methods differ in accuracy and his judgment dictates the degree of reliance to be placed upon each. Some furnish only rough approximations to his true position, yet are preferable to dead reckoning when making a coast after a period of stormy weather with no astronomic determinations of position.
The distance of visibility at sea of an object of known height as it is raised on the horizon, together with its bearing, furnishes a ready means for obtaining an approximation to the true position of a vessel. This method is of value when raising a light house at night in making a coast after stormy weather.