1876.] 



333 



[Trowbridge. 



density of the solar atmosphere at the surface of the Sun, is but little more 

 than one-half the density of hydrogen at the surface of the Earth, and at a 

 temperature of 60° Fah. The pressure on a square inch of surface, is about 

 11,000 pounds Avoir. In the case of the Earth the density of the atmos- 

 phere at the surface of the Earth, is to the density at the surface of the at- 

 mosphere, at least as great 31°°: 1. If we assume the same ratio to hold 

 for the Sun's atmosphere, Eq. (23) will give us for the hight of the solar 

 atmosphere, 426,000 miles, or about the radius of the Sun. If we make to 

 = 0, we shall find the hight of the atmosphere, with the same ratio of den- 

 sities, about 12^ miles ; the density at the Sun's surface about 740 times 

 that of the Earth's atmospliere at the surface of the Earth, or nearly equal 

 to the mean density of the Sun. It will be noticed that in the case of high 

 temperature, if we assume K = 10 (a very improbable value, it being too 

 large), we still have /\ = 0.369oAo> which gives a rare atmosphere. The 

 following table will give the density at different hights above the Sun's 

 surface : 



Relative Density. 



A 



1 



16 



1 

 SI 



1 

 'S^ 



1 

 T2y 



■5?^ 



These numbers will help us to explain the rapid movements which Prof. 

 C. A. Young and others have noticed in the solar atmosphere. If gases 

 are pent up beneath the solar surface, but finally escape with great force, 

 the rare atmosphere of the sun would not retard the motion like a dense 

 one. The less rapid motion may be due to difference of specific gravity. 

 The density of the hydrogen clouds can be calcnlated from the formulae 

 which have been given in the te.xt. D. T. 



November 24, 1876. 



[^Minutes continued from yage 292.] 

 The minutes of the last meeting of the Board of Officers 

 and Members in Council were read, and the recommenda- 

 tions of the Board were acted upon as follows: 



A committee of five, to be appointed by the Chairman, 

 after consultation, was, on motion of Mr. Price, ordered, who 

 should accept Mr. Wooten's invitation, and examine his an- 

 thracite slack fires at Reading, or elsewhere along the line 

 of the Reading Railroad. 



PROC. AMER. PUILOS. SOC. XVI. 98. 2p 



