MAGNETISM AT HALIFAX, AUGUST, 1904. — DIXON. 257 



in operation since 1841, In the United States one permanent 

 observatory has been established recently, that at Cheltenham, 

 Md., and the Coast and Geodetic Surve}'- has also in its 

 charge three other well equipped observatories, Sitka in Alaska, 

 Honolulu in Hawaii, and Baldwin in Kansas. The first 

 two rank with the Cheltenham as permanent observatories, the 

 Baldwin observatory being merely a temporary one.*^* Several 

 other permanent observatories are in contemplation. 



In the old world, the number of Tiiagnetic observations is 

 being continually increased. In a short time there will be eight 

 permanent observatories in France ; the Japanese have six in 

 operation at present. 



The choice of a site for a permanent observatorj- is a very 

 difficult matter. It is very hard to find a convenient locality 

 which will not be invaded sooner or later hy electric car lines. 

 And it has been shown by Dr. Edler in 1899, that an observa- 

 tory must be at least five miles from an electric tram line and that 

 for delicate research work the distance must be twice as great. 

 Of the great European observatories, that of Potsdam alone has 

 been able to carry on its work properly on its original site, and 

 this is owing to a decree of the Emperor, which forbids electric 

 tram lines coming within 16 kils. The other observatories 

 have been already moved or are seeking new sites. It is only 

 a few years since the site of the Toronto observatory had 

 to be changed for the same reason. 



The Observations at Point Pleasant, Halifax. 

 The observations of the elements were made at Point 

 Pleasant as being a station which could be easily occupied 

 again The position was marked by a concrete pillar sunk 4 

 feet in the ground in which was bedded a copper plug. The 

 observations were taken between 2 a. m. and 4 a. m. on the 

 mornings of August 25, 26, 1904, so that there might be no 

 local disturbance owing to the running of the electric trams. 



(1) Magnetic observations of the U. .S. Coast and Geodetic Survey, 1902. Bauer and 

 Fleming, Washington. 1903. 



