MAGNETIC OBSERVATIONS IN THE 

 BAHAMA ISLANDS 



BY 



OLIVER L. FASSIG, Ph. D., 



Section Director of theU. 8. Weather Bureau^ at Baltimore^ Md. 



INTRODUCTION. 



The instrumental equipment for the magnetic survey of the Islands con- 

 sisted of the following: (1) A Pauth theodolite, with a compass needle and a 

 tripod, the latter provided with an extra head for mounting the dip circle. 

 With this instrument observations for obtaining the true azimuth of the mark, 

 the correction of the observer's watch on local mean time, and for latitude, 

 were made. By mounting the compass needle on the telescope, the necessary 

 observations were made for obtaining the magnetic declination. (2) A Kew- 

 Casella dip circle (Plate XIV, Pig. 1), provided with two Dover needles, with 

 which the regular dip observations were made, and two intensity needles for 

 dip and relative intensity observations. This instrument was also provided 

 with a compass for making declination observations. (3) A magnetic observ- 

 ing tent. 



The entire instrumental outfit, the necessary training of observer, as well 

 as detailed instructions for making observations of magnetic declination, dip 

 and relative intensity and for the necessary astronomical observations, were 

 provided by the Superintendent of the TJ. S. Coast and Geodetic Survey. The 

 directions furnished were carefully and conscientiously followed at all stations 

 occupied, and the observations were reduced in the Division of Terrestrial 

 Magnetism of the U. S. Coast and Geodetic Survey. 



STATIONS OCCUPIED. 



The magnetic declination and dip have been determined for a number 

 of localities in the Islands since 1831. The location of the stations, the 

 values obtained and the names of the observers are given in Table I. Some 

 of the former stations were reoccupied, as nearly as practicable, in order to 

 obtain the value for the secular variation in the Islands. 



A complete set of observations was made at the following stations for 



