On this day in 1887 David Porter Heap was granted the patent fr TOPOPHONE. U.S. Patent No. 590,062.
The principal purpose of this invention is to enable vessels to change their direction of movement with relation to dangerous objects, such as vessels, icebergs, the shore, or similar obstacles to their safe movement, and thus avoid contact or collision with them, which purpose is attained by means of an instrument whereby the direction or source of sounds produced at or reflected from a more or less distant point from the instrument may be determined in time to enable the vessel to escape, if necessary, any danger the source of the sound may offer. The usefulness of this instrument is especially realized by its employment as an aid to navigation, its operation in such use being to detect and locate the direction or position of a sound-producing object in its relation to a vessel at such times when said object may not be visually perceived, as at night, during foggy weather, or by reason of distance; but the instrument is susceptible of other uses, as during a war, when it is desirable to ascertain the location of an approaching body of men or the position of a dangerous cannon and the like when the same are not visible.
