THE 



AMERICAN JOURNAL OF SCIENCE 



[THIRD SERIES.] 



Aet. LXI. — Inversion of Temperatures in the 26 - 68 day 

 Solar Magnetic Period /* by Feank H. Big-elow. 



The Epoch and use of the Ephemeris. — In previous abstracts, 

 containing some of the results of my research into the relations 

 between solar magnetism and meteorological phenomena, no 

 complete account has been given of the formation of the Epoch 

 and general use of the Ephemeris. A brief statement, how- 

 ever, interposed at this place, may be of service to some who 

 are interested in this subject. The Ephemeris depends chiefly 

 on the European Stations, Greenwich, Paris, Pola, Prague, 

 Vienna, Pawlowsk, and Tiflis, the mean geographical position 

 of the group being, longitude 17° V east, and latitude 48° 37' 

 north. Each of these stations reports 24 observations of the 

 three components of magnetic force every day, and the mean 

 of these values, therefore, is equivalent to an ordinate on the 

 scale of abscissas at noon of the station. Certain periodic 

 changes were found in the system of deflecting forces that 

 emerged from the daily residuals, of which one type was pecu- 

 liarly conspicuous. The first day following this principal 

 change was called number one of the new period, and from 

 such dates the mean epoch for the year 1887 was computed, 

 namely June 12*22, being very near the middle of the last 

 quarter of the century. Strictly this applies to the position at 

 longitude l h 8 m 28 s east, but not thinking the data of astronom- 

 ical accuracy, I have in my work taken the epoch as practi- 

 cally Greenwich mean time, the correction being —0*05 day, if 

 applied. 



* Communicated by permission of the Chief of the Weather Bureau. 



Am. Joub. Sci— Third Series, Vol. XLYIII, No. 288.— Dec, 1894. 

 28 



