Memoirs of the Kakioka Magnetic Observatory Vol.01 No.04， p.9, December, 1938
On Natural Demagnetisation of a Magnet.
Ito, K.
Abstract
An experimental formula of natural demagnetisation of a deflection magnet of cylindrical form used in the Tsingtau magnetic observatory is not only a function of time t，but depends on the number of observations n during a year. If M is the magnetic moment of the magnet and b, s, k and α are some constants，the formula is:
log 10M = b+(s+k)exp-α’.
