Key points are not available for this paper at this time.
The probability density on a sphere, exp (κ cos θ′), where θ′ is the angle between the polar and observation vectors, has recently been suggested by Fisher for the analysis of palaeo-magnetic data. In this paper, a series of approximate tests of significance is given for hypotheses about the precision constant κ and the polar vector
G. S. Watson (1956) studied this question.