APPENDIX No. 6. 



MEMORANDUM RESPECTING MAGNETICALLY DISTVRBED AND UNDISTURBED DATS AT UGLA- 



AMIE, ALASKA, 1882-'83. 



COMPUTING DIVISION, COAST AND GEODETIC SURVEY, December 6, 18.S4. 



A complete examination was made of the tabulated observations at Uglaainie of variations 

 in declination aiid in the horizontal and vertical components of the earth's magnetism for all 

 those days on which disturbances were observed at other polar stations and for those days which 

 were selected as normal or quiet days according to circular T$o. 39, issued by Dr. Wild, president 

 of the International Polar Commission. 



Our series with the Brooke differential instruments commences with September 12, 1882, and 

 for these instruments it was found that for every one of the 21 days, designated as disturbed at other 

 stations, disturbances occurred at Uglaamie in the declination and in the horizontal force and gen- 

 erally also in the vertical force, as may be seen in the accompanying list. Certain times, extending 

 over several days, present themselves very prominently, and these may aptly be designated as 

 times of stormy magnetic weather, suggesting their collective study. 



Respecting the so-called quiet days (steady condition of magnetism) it is not so easy to make 

 any positive statement, for the reason that the normal or undisturbed observations have not yet 

 been reported and treated by themselves, hence only an indistinct idea as to the limits of variability 

 can at present be had. In general the days mentioned as quiet were also found to be so at Ugla- 

 amie, yet there are exceptions, and in particular the horizontal force appears to have been rather 

 restless. The Uglaamie record would exclude the following days from the table of quiet days and 

 place them among those of ordinary ones, viz : 1882, September 30, declination and horizontal 

 force agitated; 1883, February 8, ditto; March 15, declination, horizontal and vertical force 

 agitated ; May 15, horizontal and vertica force excited; June 11, ditto. 

 Respectfully submitted by 



CHAS. A. SCHOTT, 



Assistant. 



J. E. HlLGARD, 



Superintendent United States Coast and Geodetic Survey. 



UGLAAMIE MAGNETIC EECOED, 1882-'83. 



Examination of days of disturbance mentioned in Circular No. 39, issued by President Wild, Aorem- 



her 8, 1884. 



August 5, 1882 (Observation with inferior instrument). Declination disturbance commenced 

 August 4, and was dying out in the forenoon of August 5. 



October 6, 1882. Declination greatly disturbed. Horizontal force heavily disturbed. Ver- 

 tical force slightly affected. 



October 28, 1882. Decimation slightly disturbed, extending to the 29th. Horizontal force 

 greatly disturbed on the 28th and 29th. Vertical force slightly affected. 



November 12 and 13, 1882. Declination greatly disturbed ; continued to 14tli. Strong amoral 

 display on both days. Great disturbance of horizontal force on the 12th, 13th, 14th, and 15th. 

 Vertical force disturbance excessive on 12th, 13th, and 14th. 



673 

 H. Ex. 44 85 



