302 Prof. Trowbridge ctnd Mr. Hutchins on 



10 15 

 " ^ sta * ce " - .00073x2-303 {C ' G '^ UnitS * 

 „ = 595 x 10 15 (C.G.S.) units. 



„ = 595 x 10 6 ohms. 



Some measurements in which brass knobs were used instead 

 of the platinum-foils yielded results similar to those just 

 given. The flame was, however, of a rounded conical form, 

 about 5 millim. high. The knobs were each 1-7 centim. in 

 diameter, the distance between their nearest points being 

 8 millim. A Daniell cell gave 65 divisions of a deflection on 

 the electrometer-scale. 



The results of the observations were plotted-out as described 

 above, and the equations to the curves found by trial. Taking, 

 as before, y to represent the reading on the electrometer-scale 

 at the time t, in minutes, I find : — 



With the + pole of the battery to earth, in two different 

 measurements, 



on - ., A --039«- -00148^2 

 y = 315 K 10 , 



Q/IA w i A--03W- -00092*2 



y = 340 x 10 

 The negative pole put to earth gives 



Q1 O.K 1 n-"°328*--000395*2 



y = old x 10 



These quantities are of the same dimensions as those given 

 above, and need not be discussed further here. 



Gordon's College, Aberdeen. 

 August 1887. 



XXXIX. Oxygen in the Sun. By Professor John 

 Trowbkidge and C. C. Hutchins*. 



SINCE the time it was announced that hydrogen existed 

 in great abundance in the sun's atmosphere and was a 

 controlling element in its economy, there have been no more 

 interesting questions in solar physics than those touching 

 the presence of other gases in the sun's body and atmo- 

 sphere; and when we consider the important part that oxygen 

 plays in terrestrial affairs, the great variety of combinations 

 into which it enters, and its high constituent percentage in 

 the composition of the earth itself, a peculiar interest, second 

 to that of no other element perhaps, attaches to its probable 

 presence in the sun. 



The investigation of the spectrum of oxygen as a research 

 by itself, and as connected with its presence in the sun, has 



* From an advance proof from the Proceedings of the American 

 Academy of Arts and Sciences, vol. xxiii. Communicated by Professor 

 J. Trowbridge, of Harvard University, Cambridge, Mass., U.S. 



