Hard to Hear Airplane at 80a.While It Is widely known that an airplane can be heard for some distance off on land, on water the lapping of the waves and the whistling of the wind through the rigging and superstructure of a vessel make it almost impossible to hear the power plant of an approaching seaplane until it is almost ovebead; hence the submarine plying the surface has slight warning of an impending seaplane attack until it is often too late to escape.—Scientific American.