151 



The Committee of Publication reported, that the sixth 

 volume of the Transactions of the Society was completed. 



Professor A. D. Bache made a verbal communication, accom- 

 panied by a chart, showing the changes of magnetic variation 

 on the last two terms of the German Magnetic Association; 

 namely, the 30th of August and 30th of November, of the pre- 

 sent year. 



Professor Bache also presented, on behalf of the Committee 

 on Magnetic Observations, appointed at the last meeting of the 

 Society, a Memorial, addressed to the Secretary of War of the 

 United States, inviting the establishment of Magnetic Observa- 

 tories, and co-operation in the system of magnetic and meteor- 

 ological observations now in progress under the direction of 

 the British Government. 



Hall of the American Philosophical Society, 



Philadelphia, December, 1839. 

 To the Hon. Joel R. Poinsett, Secretary of War, tyc. Sfc. 



Sir : — The undersigned have been appointed a Committee of the 

 American Philosophical Society, to call your attention to, and to in- 

 vite, through the medium of your department, co-operation in, the 

 extensive system of magnetic and meteorological observations about 

 to be made under the direction of the British Government, and in con- 

 nexion with their Antarctic expedition, particularly directed towards 

 magnetic investigations. 



The science of terrestrial magnetism has of late years made great 

 advances, through the instrumentality of Humboldt, Hansteen, Gauss 

 and others, and has now reached that point where a system of com- 

 bined observations at widely distant points over the surface of the 

 globe, appears to be necessary to its further progress : desultory effort 

 has already done all that it is competent to effect. Such a series of 

 systematic observations has now been set on foot by the British 

 Government, directed to a better determination of the magnetic lines, 

 for the use of navigators, and to the accurate investigation of the 

 magnetic elements for theoretical purposes. The objects embraced 

 are the measurement of the magnetic intensity, dip, and variation, at 

 different stations, by a nautical expedition, and at fixed observatories, 

 and especially the investigation of the variations of these elements at 

 the latter points. As subsidiary to these objects, combined meteorolo- 



