Values of the magnetic elements at the observatories of the United States Coast and Geodetic Survey at the time of the solar eclipse of May 29, 1919

Abstract

In order to supply data for a comparison of the magnetic condition of the Earth within and outside the eclipse belt at the time of the solar eclipse of May 29, 1919, values of the declination, horizontal intensity and vertical intensity have been derived from the magnetograms of the five magnetic observatories of the United States Coast and Geodetic Survey for every five minutes of the period from 10h to 16h30m Greenwich mean time. In reading the ordinates a graphical integration was made, so that a tabular value is approximately the average value for the 5‐minute period of which the tabular time is in the middle.Tables are given showing the diurnal variation of the magnetic elements for selected quiet days: May 29 to June 7 for Puerto Rico, Cheltenham and Sitka; May 28–30, June 1–7 for Tucson; May 27–31 for declination and vertical intensity, and May 8, 16, 29, 30, 31 for horizontal intensity for Honolulu. A plus sign indicates eastward deflection of the north end of the needle, or increasing intensity.