86 Coast Lines and Magnetic Declination. 



^ 



light during the Admiralty enquiry into the causes that 

 led to the disastrous loss of H.M.S. "Serpent" off Cape 

 Villano, on the coast of Spain, November, 1890.* 



Among other reports read before the Court was one from 

 the captain of the Spanish screw steamer " Beneta," who 

 stated that, during the 15 years he had been trading along 

 the north coast of Spain, he did not remember to have 

 observed any deviation of the compass on account of the 

 attraction of the iron ore mountains, but he always noticed 

 that when steering on a southerly course the error of the 

 compass was N.E. ; that was to say, that the local variation 

 of the compass was eight or ten degrees N.W. instead of 

 18 or 20 degrees as shown on the Admiralty chart of the 

 declination. Now, a glance at the chart will show that the 

 north coast of Spain extends parallel to the earth's equator 

 for a distance of nearly eight degrees, or 400 miles, and 

 has, consequently, a maximum polarising influence on the 

 compass to diminish the amount of the secular change of 

 the declination, as observed by the captain of the " Beneta " 

 and as set forth in my papers. 



It would therefore appear that some of the declination 

 lines, as represented on the charts, do not partake of that 

 symmetrical character that is generally accorded to them 

 and that caution will be required in the use of variation 

 charts off the greatly extended coast lines of deep seas 

 where the rate and range of the secular declination are 

 large in amount. 



* The London Times, December 17th, 1890. 



