PHILOSOPHICAL SOCIETY OF WASHINGTON. 85 



A conversational discussion followed, in which Messrs. Mason, 

 Woodward, Hilgabd, and Taylor participated. 



Mr. E. S. HoLDEN spoke of observations of the sun at the U. 

 S. Naval Observatory in search of the supposed interior planet 

 Yulcan. These were made for three successive days, chiefly with 

 the comet-seeker, occasionally with the nine-inch refractor, but 

 without success. 



Messrs. Newcomb and Taylor discussed the theory of Yulcan, 

 and the probabilities of the existence of such a planet. 



Mr. Joseph Henry described recent experiments under the 

 direction of the U. S. Lighthouse Board, particularly on the 

 combination of sounds produced by two syrens of the same pitch, 

 and which were heard at a much greater distance than one alone; 

 and the construction of a buoy so as to give sounds by the force 

 of the waves. 



Mr. J. W. Powell spoke of the requirement by geologists of 

 more time, less thickness of the earth's crust, and more contrac- 

 tion than physicists were ready to allow. 



Messrs. Newcomb, Hilgard, Taylor, and Gill participated 

 in the discussion which followed. 



lllTH Meeting. October 21, 18t6. 



Vice-President Welling in the Chair. 



Twenty-two members and visitors present. 



Mr. E. B. Elliott made some remarks on 



monetary standards ; 



referring to recent action of France, Germany, Austria, and 

 Spain, in limiting the coinage of silver, and restricting the use 

 of silver coins mainly to a subsidiary currency. 



Some discussion followed, chiefly with regard to the large 

 amount of silver required by Germany at the present time, in 

 which Messrs. Abbe, Newcomb, and Welling participated. 



