400 THE CHEMISTRY OF THE SUN. [CHAP. 



The pith and marrow of the work referred to in this chapter 

 may be stated as follows : 



(1) At the highest temperatures we can get at here, or 

 are acquainted with in the celestial bodies, the most orthodox 

 chemists agree we are dealing with the chemical " atom." 



(2) Most chemists will accept Clerk-Maxwell's definition of 

 an atom that it is "a thing which cannot be cut in two" to 

 which I will add that it cannot be doing two opposite things at 

 the same time. 



(3) The line spectrum is held to be the radiation from the 

 " atom " of a chemical substance. 



(4) We have found the spectra of the same substance in 

 spots and prominences to be complementary to each other. 

 That is to say, in both cases certain vibrations of the same 

 "atom" have been stopped. 



(5) We have found the thing which cannot be cut in two 

 indicating rest, and a motion of thirty miles a second, at the 

 same time. 



(6) We have found the " atom " of calcium, a thing which 

 cannot be doing two opposite things at the same time, in sun- 

 spots giving as H and K bright in photographs while the blue 

 line is absorbing. 



(7) We now find that the " atoms " surrounding the core of the 

 arc absorb only certain radiations. 



(8) We now find that similar " atoms " vibrate with certain 

 wave-lengths at one pole of the arc, and with different wave- 

 lengths at the other. 



It must not be forgotten that the vibration of an " atom " 

 according to the received views is a very serious affair. The 

 vibration of the atom of cerium for instance according to that 

 view is more complex than all the vibrations of all the sub- 

 stances in the solar atmosphere put together ; for the number of 

 lines in the spectrum of cerium (the specimen was supplied to 

 me by my friend Dr. Holtzmann as puerissimo, having been 



