Chase.] OO^ [April 15, 



Oa scrutiny of the ballot boxes the President declared the 

 following persons duly elected members of the Society. 



Prof. Claudio Jannet, of Paris. 



Prof. Paul Leroy Beaulieu, of Paris. 



M. Emile Malezieux, of Paris. 



Prof. E. A. Barber, of West Philadelphia. 



Dr. Jas. A. H. Murray, of Mill Hill, London. 



Hon. William Butler, Judge of U. S. District Court, 

 Eastern District of Pennsylvania. 



Mr. Wm. Woodnutt G-riscom, of Philadelphia. 



And the meeting was adjourned. 



Photodynamie Notes, II. By Pliny Earle Chase, LL.D., Professor of 

 Philosophy in Haverford College. 



(Bead before the American Philosophical Society, April 15, 1881.) 



16. Weighing the Sun by a Soap Bubble. 



In the well-kuown experiment of inflating a soap bubble with a mixture 

 of oxygen and hydrogen, and exploding it by a candle, there is an oppor- 

 tunity for studying various radiodynamic relations. The equilibrium, 

 which usually exists between the gravitation of the particles towards the 

 sun and towards the earth, is suddenly and violently disturbed. During 

 the restoration of equilibrium, there are simultaneous tendencies to the 

 production of orbital velocities, about the earth and about the sun . 



The height of virtual focal projection which represents elliptic orbital 

 r 

 velocity is -g (1 + ^) j the height at Earth's equatorial surface, which is 



3962.8 

 in unison with orbital projection, being — x — X 1.01677 = 3014.16 miles. 



/ 1389.6 \ 



Dividing this height by the French thermal unit IC=: 528O nule-poundsl 



and multiplying by 9, because 9 pounds of gas are lifted by 1 pound of 

 combustible, we get 68878.2 calorics as the thermal equivalent of the ex- 

 plosion. Naumann* gives the following experimental values : 



Thomsen 68376 



Favre and Silbermann 68924 



Dulong 69486 



Hess 69584 



Grassi 69332 



Andrews 67616 



Mean 68886 



* Handbuch der Chemie, p. 290. 



