702 REPORT — 1903. 



oceans differs in intensity from that of the dry land we inhabit. A connection 

 between the disturbances of the earth's crust in earthquakes and disturbances of 

 the magnetic needle also seems to exist, although the evidence on this point is not 

 conclusive. 



Magnetic Survei/s. 



Previously to the year 1880 there were two periods of exceptional activity on 

 the part of contributors to our knowledn^e of the earth's magnetism, during which 

 the scientific sailor in his ship on the trackless ocean combined with his brethren 

 on land in making a magnetic survey of the globe. 



The first period was that of 1843-49, during which not only were fixed obser- 

 vatories established at Toronto, St. Helena, Capetown, and Hobart for hourly 

 observations of the movements of the magnetic needle, but, to use Sabine's words, 

 ' that great national undertaking, the Magnetic Survey of the South Polar Regions 

 of the Globe,' the forerunner of our present Antarctic Expedition, was accom- 

 plished by Ross and his companions almost entirely at sea. 



This Antarctic survey was carried out during the years 1840-45, and the 

 results given to the world as soon as possible by Sabine. The results afterwards 

 formed a valuable contribution when constructing his maps of equal lines of Mag- 

 netic Declination, Inclination, and Intensity for tlie whole world, a great work for 

 the completion of which Sabine employed every available observation made up to 

 the year 1870, whether on land or at sea. 



Readers of these contributions cannot fail to bo struck with the great number 

 of observations made by such travellers as Hansteen and Due, Ermau and AVrangel, 

 extending from Western Europe to far into Siberia. 



The second period was that of 1870-80, during wliich not only was there much 

 activity amongst observers on land, but that expedition so fruitful to science, 

 the voyage of H.M.S. ' Challenger,' took place. During the years 1872-76 we find 

 the sailor in the ' Challenger ' doing most valuable work in carrying out a magnetic 

 survey of certain portions of the great oceans, valuable not only for needful uses in 

 making charts for the seaman, but also as a contribution to magnetic science. 



Prior to this expedition very little was known fmni observation of the distri- 

 bution of Terrestrial Magnetism in the central regions of the North and South 

 Pacific Oceans, and Sabine's charts are consequently defective there. 



Combining the 'Challenger' magnetical i-esults with tlinse of all available ob- 

 servations made by others of H.M. ships, and by colonial and foreign governments, 

 I was enabled to compile the charts of the magnetic elements for the epoch 1880, 

 which were published in the report of the scientific results of H.M.S. ' Challenger.' 

 I will venture to say that these charts give a fairly accurate representation of the 

 normal distribution of the earth's magnetism between parallels of 70° N. and 

 40° S. Beyond these limits, either northward or southward, there is a degree of 

 uncertainty about the value of the lines of equal value, especially in the Southern 

 reo-ions, an uncertainty which we have reason to hope will be dissipated when we 

 know the full results obtained by Captain Scott and the gallant baud he com- 

 mands, for as yet we have to be content with some eddies of the full tide of his 

 success. 



Until the ' Discovery ' was built, tbe ' Cliallenger ' was the last vessel specially 

 selected with a view to obtaining magnetic observations at sea, so that for 

 several years past results obtained on land have been our mainstay. Thus, 

 elaborate magnetic surveys with fruitful results have been carried out in recent 

 years in the British Isles by Riicker and Thorpe. France, Germany, Holland, and 

 some smaller districts in Europe have also been carefully surveyed, and British 

 India partially so, by Messrs. Schlaglntwelt in 18-57-58. The latter country is 

 being again magnetically surveyed under the auspices of the Indian Government. 



On the American continent the Coast and Geodetic survey of the vast terri- 

 tories comprised in the United States, which has been .so many years in progress, 

 has been accompanied by an extended maf^netic survey during the last fifty-two 

 years, which is now under the able direction of Dr. L. A. Bauer. Resulting 

 from this some excellent charts of the magnetic declination in the United States 



