112 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 



hagen type, was run at quick speed for giving accurate times of inci- 

 dence of special perturbations in the field, such as sudden commence- 

 ments of magnetic storms. 



Until a year or two ago, when this quick-run magnetograph was 

 perfected in Denmark, it was impracticable to specify times of 

 perturbations on magnetic traces to a greater accuracy than 1 or 

 even 2 minutes, so that such questions as the mode of propagation 

 of world-wide sudden commencements — whether they appeared 

 simultaneously over the earth, whether they traveled from east to 

 west, or whether ihej were propagated along meridians — could not 

 be decided with certainty. Now, among disturbances in the earth's 

 magnetic field during the Polar Year, a well-marked sudden com- 

 mencement on April 30, 1933, heralding a big disturbance on May 1, 

 was recorded on the quick-run magnetographs at most of the Polar 

 Year stations. Preliminary measurements show that, within about 

 2 seconds, this movement was recorded simultaneously at places as 

 far distant as Copenhagen, Thule in northwest Greenland, Rae in 

 northwest Canada, and probably also at Huancayo in Peru and 

 Watheroo in Australia. Thus an early result of the Polar Year 

 activities may be to throw important light on this long discussed 

 question and therefore, directly, on the mechanism producing mag- 

 netic storms. 



The electric light for the recording mechanisms of this magnetic 

 apparatus was supplied by a Delco motor generator and accumulator 

 battery we took with us for the purpose. 



Of control magnetic instruments we had a double set representing 

 the old and new systems of magnetic observing. A Kew magnetom- 

 eter and dip circle served as comparison checks and also for parallel 

 work at the old Fort Rae substation, where magnetic observations 

 had to be carried out to determine the secular change since 1882; 

 while a Smith magnetometer and dip inductor were used as the stand- 

 ard instruments for determining horizontal force, declination, and 

 inclination at the main base. The use of electromagnetic methods for 

 determining the value of the earth's magnetic field is of special ad- 

 vantage in such a place as Rae, wdiere magnetic disturbance is so 

 frequent and on such a large scale. Observations which took the best 

 part of an hour by the older technique now require only a few min- 

 utes — provided everything goes as it should. 



Our meteorological equipment was very complete. Almost every 

 instrument was run in duplicate so that records might be maintained 

 complete in case of clock stoppage or unforeseen accident. And such 

 safeguards proved necessary, especially where clocks running out of 

 doors were concerned. Expecting trouble with the temperature and 

 humidity recorders in the Stevenson screen in the winter months, we 



