237 



From these data it would seem that the apparent secondary revo- 

 lution of B round the common centre of gravity of B and A is at 

 the rate of about one half a degree per day, and the foreshortened 

 daily departure of B from A in space, is about 1000 miles, and that 

 so far, the revolution round each other, and the increase of distance 

 asunder, are nearly uniform. 



I am quite unable to give any theoretical explanation of the phe- 

 nomenon. 



Yours, truly, 



S. C. WALKER. 

 To Prof. A. D. Bache, LL.D. 



Prof. A. D. Bache made some remarks on the progress of 

 the coast survey, under his superintendence, and illustrated 

 them by a number of diagrams. 



On motion of Dr. Elwyn, the letter from the American 

 Academy of Arts and Sciences was referred to a committee, 

 consisting of Dr. Emerson, Mr. Charles M'Ewen, and Prof. 

 Cresson. 



Stated Meeting, February 20. 

 Present, seventeen members. 



Dr. Chapman, President, in the Chair. 



A letter was announced and read: — 



From the American Academy of Arts and Sciences, dated 

 Boston, Feb. 8, 1846, inviting the cooperation of the American 

 Philosophical Society, in a petition to Congress, to print an 

 additional number of copies of the Reports of the U. S. Ex- 

 ploring Expedition. 



The communication was referred to a Committee, consist- 

 ing of Dr. Elwyn, Prof. Frazer, and Dr. Patterson. 



The following donations were announced: — 



FOR THE LIBRARY. 



Proceedings of the Geological Society of London. With Plates in 

 illustration of the Papers abstracted. Session 1844 — 45. VoL 

 IV. No. 104. Parts. Qvo.— From the Society. 



