PHILOSOPHICAL SOCIETY OF WASHINGTON. 33 



Remarks were made by Messrs. Hilgard, Powell, Dall, Al- 

 VORD, Parker, Mason, Ward, Abbe, White, Gill, Woodward, 

 Harkness, aud Winchell, the discussion taking a wide range. 



Mr. J. R. Eastman exhibited and described 



A PERSONAL EQUATION INSTRUMENT 



devised by him in 1875, and successfully used at the Washington 

 Observatory in determining the absolute as well as relative equa- 

 tions of observers with the transit instrument. 



Remarks were made by Mr. Paul. 



Mr. J. E. Hilgard exhibited two 



PHOSPHORESCENT CLOCKS, 



stating that the faces were coated with calcium-sulphide, and that 

 after exposure to solar light they would remain luminous in the 

 dark during the greater part of a night. 



Mr. Antisell explained that a number of sulphides possess 

 this property of phosphorescence. 



159th Meeting. March 29, 1819. 



The President in the Chair 

 Thirty-eight members and visitors present. 

 Mr. S. jS'ewcomb made a communication on 



THE RECURRENCE OP ECLIPSES. 



The subject was discussed by Messrs. Abbe and Taylor. 

 Mr. L. F. Ward read a paper on 



THE ORIGIN OF THE CHEMICAL ELEMENTS, 



Dr. W. K. Brooks, of the Johns Hopkins University, read a 

 paper on 



