An instrument for finding the time by night from the position of the two 'pointers' of the Great Bear or Little Bear constellations. It consists of a wooden or metal disc with a handle, marked with an anticlockwise annual calendar scale. Superimposed on this is a smaller disc, pivoted at its centre and marked with an hour scale 2 X 12 anticlockwise, carrying an index reading on the date scale or a pair of indexes marked 'GB' or 'LB' for Great or Little Bear. Superimposed again is an index arm projecting well beyond the discs. There is a central hole through the pivot system. To find the time, the observer faces north and sets the date index to the date of use. He then sights the Pole Star through the central hole and rotates the index until it is in line with the pointers of the Great or Little Bear, according to the index employed. The time of night is read off on the 2 X 12 hour scale.