238 



by the sum of the forces developed by the earth's magnetism in the 

 two vertical bars. 



The practical question was whether the horizontal bar could be 

 brought to rest, or nearly so, in time to observe its new position ; the 

 copper rectangles used in the declination instrument being obviously 

 inadequate to produce this effect. Prof. B. stated that his first assist- 

 ant and himself had both found this result practicable, even with the 

 short intervals of term-day observations. This was effected by a 

 change in the position of the movable vertical bar producing half the 

 amount of deflection ; — by allowing the horizontal magnet to make one 

 excursion in the direction of the impressed force, and when in motion 

 for the return, checking it by completing the change of position of the 

 vertical bar. 



Prof. Bache further proposed the use of tubes of sheet iron for the 

 temporary magnets, as they can be more readily annealed, and all 

 permanent magnetism may thus be more easily destroyed in them, 

 than in bars. 



The Treasurer presented the annual report of the state of the 

 funds of the Society, which was referred to the Committee of 

 Finance. 



Mr. Lea, chairman of the Publication Committee, presented 

 the annual report in relation to the Society's Transactions. 



The number of subscribers to the Transactions is 107. The 

 number of copies distributed in exchange with other Societies, &c, is 

 71, and the number sold to non -subscribers since the last annual re- 

 port, has been 10. The balance of funds in the hands of the Com- 

 mittee is $283.32. 



Stated Meeting, December 16. 



Present, thirty-two members. 



Dr. Bache in the Chair. 



Letters were read: — 



From the Academy of Sciences of Paris, dated 5th August, 

 1842,— the Royal Academy of Turin, dated 28th Oct. 1842, — 

 the Society of Antiquaries of London, dated 18th Nov. 1842, — 

 the Auxiliary Society of National Industry of Rio Janeiro, 



