MAGNETIC OBSERVATIONS IN ALASKA 



By Daniel L. Hazard, Coast and Geodetic Survey 



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NE of the prime requisites for 

 successful navigation is a knowl- 

 edge of the magnetic declination 

 or, as the mariner calls it, the variation 

 of the compass, in order that the navi- 

 gator may properly direct his course 

 when observations of the sun or stars are 

 impossible. The portion of the earth's 

 surface where the compass needle points 

 true north is very limited in extent. Not 

 only does the magnetic north in general 

 differ from the true north, but the 

 amount of difference changes in going 

 from place to place ; so that, for example, 

 in crossing the United States from Maine 

 to Seattle the direction of the compass 

 needle would change from 20° west of 

 true north to 23 east of true north. 



At the present time the distribution of 

 the earth's magnetism is known at least 

 approximately for the greater portion of 

 the earth's surface, and world charts are 

 issued from time to time by the hydro- 

 graphic offices of several countries, from 

 which the variation of the compass at 

 any place may be obtained with an accu- 

 racy not far short of the needs of the 

 navigator. Up to comparatively modern 

 times, however, no such charts existed, 

 and it was necessary for the navigator to 

 determine the variation of his compass at 

 every opportunity, both on land and on 

 shipboard. Hence the early magnetic 

 data in Alaska, as in many other coun- 

 tries, have been obtained from the ac- 

 counts of the voyages of those pioneers 

 of the sea who visited that territory 

 either in searchof the Northwest Passage, 

 or for the definite purpose of adding to 

 our knowledge of the earth's surface, or 

 perhaps purely from a spirit of adven- 

 ture. Bering, Cook, Ua Perouse, Port- 

 lock, Meares. Malaspina, Vancouver, 

 Disianski, Kotzebue. Golofnin, Wrangell, 

 Franklin, and many others touched at 

 various places in Alaska and each con- 

 tributed his share to our knowledge of 

 the earth's magnetism in that part of the 

 world. 



Early in the nineteenth century a fresh 

 impetus was given to the study of ter- 

 restrial magnetism by the united efforts 

 of von Humboldt, Gauss, Kupffer, and 

 Sabine, and magnetic observatories were 

 established in different parts of the 

 world. In order to secure a wide distri- 

 bution of stations, it was determined to 

 place one of the Russian observatories in 

 Alaska. In 1841 a wooden building was 

 erected on Japonski Island, just across 

 the harbor from Sitka, and observations 

 were begun in March, 1842, by observers 

 who had been trained for the work at 

 Saint Petersburg. The observations, so 

 far as they have been published, consisted 

 principally of hourly observations of 

 declination from 4 a. m. to 8 p. m., and 

 in some years for the whole 24 hours. 

 The work was kept up until October, 

 1867, when the territory became the 

 property of the United States. 



Since the acquisition of Alaska by the 

 United States, the magnetic survey of the 

 territory has kept pace with the charting 

 of the coast and exploration of the in- 

 terior, the most of the observations hav- 

 ing been made by officers of the Coast 

 and Geodetic Survey. Owing to the un- 

 settled condition and inaccessibility of 

 most of the territory, no attempt has been 

 made to carry out a systematic magnetic 

 survey such as is possible in a fully-de- 

 veloped country. With few exceptions 

 the surveying parties engaged in other 

 work have been provided with magnetic 

 instruments, and magnetic observations 

 have been obtained at one or more places 

 in the area covered by each season's 

 work. 



In 1900, when an increase of appro- 

 priation made it possible for the Coast 

 and Geodetic Survey to prepare for the 

 erection of several magnetic observato- 

 ries, the importance of having one in 

 Alaska was recognized and Sitka was se- 

 lected as the best available location. The 

 site of the old Russian observatory on 

 Japonski Island was no longer suitable ; 



