246 DEIERMINATION OF THE ELEMENTS OF TERRESTRIAL 



netism. Dr. L. A. Bauer, Chief of the Division of Terrestrial 

 Magnetism, U. S. Coast Survey, was appointed to control this 

 department and an annual grant of twenty thousand dollars 

 .alloted to carry out the work. 



Magnetic Declination. 

 In Europe the science of terrestrial magnetism began with 

 the disco veiy of magnetic declination in 1492. In this year 

 Columbus, on his first great voyage, found that except in certain 

 places the compass needle did not point to the pole and that the 

 angle it made with the true meridian varied from place to place. 

 Eighteen years later, in 1510, George Hartmann made the first 

 recoided measurements of magnetic declination on land. At 

 Rome in this year, he found the declination 6*^ E. and at Nurem- 

 burg 10° E. In the succeeding years many observations of 

 declination were made, and in England the first work published 

 on the subject was by William Borough, " A Discours of the 

 Variation," in 1581. In this book the value of the declination 

 at London for 1580 is given as 10° 15' E. By such observa- 

 tions all over the earth, at sea and on land, the declina ion was 

 noted, and in 1599 Simon Stevin published at Leyden, under 

 the patronage of the Dutch admiral, Count Moritz, a list of 

 magnetic declination determinations. This early interest in 

 magnetic observation has been kept up by the Dutch. At home 

 and in their colonies magnetic work has been carried on 

 energetically, and at the present day the survey of Holland is 

 the most complete in Europe. Dr. L. A. Bauer has published *'> a 

 very complete list of magnetic declination observations made 

 before the year 1600, and points out that the declination over 

 the greater part in Europe in the sixteenth century was east of 

 north. 



Dip. 



The second element of the earth's macrnetism, the inclina- 

 tion or Dip, was discovered by Robert Norman, an instrument 



(1) Magnetic Declination Tables for 1902, by L. A. Bauor. U.S. Coaatand Geodetic 

 Survei/. 



