hodometer: device for measuring distance by means of a wheel, pushed along the ground, attached to a geared movement with a dial or other form of distance register.
horary quadrant: quadrant used to tell the time, usually from a measure of solar altitude, see article on the quadrant.
horizon obliquus: line denoting the local horizon on an astrolabe latitude plate, see article on the astrolabe.
horizon rectus: east-west line on an astrolabe latitude plate, see article on the astrolabe.
