3. On the Decennial Period in the Mean Amplitude of the Diurnal Oscillation and Disturbance of the Magnetic Needle and of the Sun-spot Area

J. A. Broun
1878 Proceedings of the Royal Society of Edinburgh  
The author, in presenting results relating to the decennial period derived from observations made at Trevandrum during twenty-two years, has sought a redetermination of the mean duration of that period, as shown by preceding magnetical observations connected with his own. The relation of the frequency and area of sun-spots to the amplitude of the diurnal movements of the magnetic needle gives an increased value to this investigation.
doi:10.1017/s0370164600032041 fatcat:kpcud7r6ufdubjpchbo2d6tuuu