DEPARTMENT OF TERRESTRIAL MAGNETISM. 165 



weight of the magnet will be disclosed for the various positions, the magni- 

 tude of the differences depending upon the closeness with which the earth's 

 magnetic forces are coupled at the place of observation. 



With a view of testing this matter and establishing the degree within 

 which the coupling takes place in various magnetic fields, the Director, in 

 connection with his trip of inspection to the Galilee at Sitka, made a series 

 of weighings of an octagonal magnet, using a Becker non-magnetic analytical 

 balance. These weighings were made at the following points: Sitka (aux- 

 iliary building of the Sitka Magnetic Observatory), Treadwell Point (region 

 of great local disturbance). Juneau (Occidental Hotel), Victoria (in the 

 open air, as also inside a hotel), Baldwin, Kansas (Magnetic Observatory), 

 Washington, District of Columbia, and Cheltenham, Maryland (Magnetic 

 Observatory). 



In a region of pronounced local disturbance, such as exists at Treadwell 

 Point, there is no question as to appreciable differences in the weighings of 

 the magnet in the four positions above enumerated. At the other places 

 mentioned, where the local field is approximately uniform, there exist some 

 indications that exact coupling may not invariably take place. At Treadwell 

 Point the average difference for four points of observation was about 

 1/500000 part of the weight of the magnet (33.627 ± grams), the weight for 

 north end south being greater ; for the two vertical positions the average dif- 

 ference was nearly i/iooooo part, the weight for north end down being the 

 greater. 



Further observations will be required before more definite announcement 

 can be made regarding this interesting question, the main purpose at the 

 present time having been to get some idea as to the magnitude of the quan- 

 tities to be measured. The investigation has been amplified so as to include 

 more orientations of magnet and be conducted with various magnets and in 

 various magnetic fields. 



ATMOSPHERIC ELECTRICITY WORK. 



As stated in connection with the work of the Galilee, Mr. P. H. Dike, after 

 having made various experiments and investigations at Washington to deter- 

 mine upon the feasibility of certain atmospheric electricity observations at 

 sea, was assigned to the Galilee at Sitka on August i to secure the practical 

 experience required under the actual conditions involved. A synopsis of 

 what he proposes to attempt is contained in the June, 1907, issue of the 

 journal Terrestrial Magnetism. A preliminary report has been received 

 from him embodying the result of the experiments which he was enabled to 

 carry out on the recent cruise of the Galilee from Sitka to Honolulu, August 

 10 to 28. He states: "Up to the present most satisfactory work has been 

 done with the Gerdien conductivity apparatus ; observations have been made 

 on 5 days, giving results fully as high as are expected on land, being of the 



