32 abstracts: terrestrial magnetism 



TERRESTRIAL MAGNETISM.— Results of observations made at the 

 Coast and Geodetic Survey Magnetic Observatory at Cheltenham, Md., 

 1907 and 1908. D. L. Hazard. Washington, Government Printing 

 Office, 1911. Restdts of observations made at the Coast and Geodetic 

 Survey Magnetic Observatory at Sitka, Alaska, 1907 and 1908. D. L. 

 Hazard. Washington, Government Printing Office, 1911. Resultsof 

 observations made at the Coast and Geodetic Survey Magnetic Observatory 

 near Honolulu, Hawaii, 1907 and 1908. D. L. Hazard. Washing- 

 ton, Government Printing Office, 1911. 



In terrestrial magnetism the Coast and Geodetic Survey has published 

 during this calendar year, the results of its magnetic observatory work 

 at three of its five magnetic observatories for the years 1907 and 1908, 

 viz: for Cheltenham, Maryland; Sitka, Alaska; and Honolulu, Hawaii. 

 Each volume contains the results of two years observations. The hourly 

 values of the magnetic declination, the horizontal and vertical magnetic 

 intensity are tabulated for the whole period. The mean nourly values 

 of these magnetic elements are given for each month as well as those for 

 the " ten least disturbed days." Based upon the data in these tables are 

 other tables showing the diurnal variation of the magnetic elements. 

 A summary of monthly mean values of the different magnetic elements 

 is also given. 



The volumes also contain tabulations of the principal magnetic dis- 

 turbances recorded at the observatories. The actual records of a num- 

 ber of these magnetic disturbances or "magnetic storms" are reproduced 

 to three-fourths the original size, and are referred to Greenwich mean 

 time for facility of comparison with the records of other observatories. 



The magnetic data conform as far as possible with the recommenda- 

 tions of the Commission on Terrestrial Magnetism of the International 

 Meteorological Committee as expressed at its several meetings since 

 1896. 



In these volumes is also given the data of all earthquakes recorded on 

 the seismographs operated at the magnetic observatories during 1907 

 and 1908. 



At the present time all of the magnetic observatories of the Coast and 

 Geodetic Survery are making special registration observations of the 

 magnetic elements (declination, horizontal and vertical intensity) at 

 stated periods, in response to the request of the Royal Society of Lon- 

 don for international cooperation in magnetic work on certain term 

 days from May, 1911, to January, 1912, covering a portion of the period 

 of the magnetic work of the English South Polar Expedition now in the 

 antarctic regions. 



