Abstract
A new measure of magnetic activity—the American magnetic character‐figure CA—was inaugurated on March 13, 1937. As discussed in a previous paper1 the purpose of this new measure is to supply a timely and adequate index of the Earth's magnetic condition for comparison with related phenomena, particularly radio‐transmission conditions. Since its inception the American magnetic character‐figure seems to have fulfilled this need. Weekly bulletins on the Earth's magnetic activity have been issued to interested persons and organizations by the Department of Terrestrial Magnetism of the Carnegie Institution of Washington on Wednesdays, covering the seven‐day interval ending at 24h GMT the preceding Friday.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
