(under subclass 178) Apparatus responsive to relative motion of a fluid medium and a craft for use in determining the speed of the craft with respect to the fluid medium on which it is supported or in which it is immersed. The speed may be integrated with respect to time in order to obtain the distance traveled.
(1) Note. This subclass includes analogous devices for measuring the relative speed of land vehicles with respect to the air.
SEE OR SEARCH THIS CLASS, SUBCLASS:
861+, for mere flow meters which might be carried on a craft.