Huancayo Magnetic Observatory January to March, 1936

(Latitude 12° 02′.7 S., longitude 75° 20′.4 or 5h01m.4 W. of Gr.)January 24–25—This minor disturbance was conspicuous for its sudden commencement and for a very great decline inH directly following the commencement. At 16h 45m there was a sudden commencement in all three elements,H increasing 50 gammas in eight minutes andD andZ in the same interval increasing respectively two minutes and one gamma. At 16h 53m, immediately following the increase associated with the sudden commencement, there began a long steady decline inH which ended at 20h 38m after a decrease of 368 gammas. The value ofH at 16h 53m (approximately 29,800 gammas) was the maximum for the day and that at 20h 38m the minimum. Following the minimum,H gradually increased to normal value by 5h on January 25, there being minor fluctuations superposed on the general trend.D andZ, during the interval in question, showed numerous minor perturbations superposed on the usual diurnal trend. Throughout January 25 and 26 all three elements showed marked fluctuations without departing greatly from the usual diurnal curves.