37 



connection with the Observatory. The doubled 

 efficiency resulting from the combination of the 

 two is of the same character as that which follows 

 from the joint prosecution of the solar and stellar 

 work. 



PRESSURES AND MOTIONS IN THE 

 SOLAR ATMOSPHERE. 



I have mentioned the displacement of lines by 

 pressure as a laboratory problem. The applica- 

 tion of the results to the interpretation of line 



FIG. 29. Magnet for Zeeman Effect. 



displacements observed in various parts of the 

 solar atmosphere has yielded much new informa- 

 tion. If the vapors in question are moving toward 

 or away from the observer, displacements due to 

 motion must be distinguished from those caused 

 by pressure; this can be done with certainty by 



