EFFECT OF PRESSURE UPON ARC SPECTRA. NICKEL. 

 TABLE IV. (continued). 



219 



Line. Wave-length. 



155 atmospheres. 



172 4401-70 



174 4437-17 

 176 4459-21 



177 4462-59 



178 4470-61 



182 4520-20 



185 4547-30 

 188 4592-69 



189 4600-51 



190 4605-15 



191 4606-37 



Immensely broadened. Unsym- 

 metrical to red. Displacement 

 approximately 0-6 A.U. Mean 

 displacement per atmosphere : 

 0-0039 A.U. 



Doubtful whether the hazy band is 

 due to this line or a close neigh- 

 bour. 



Immense unsymmetrical broadening. 

 Displacement approximately 



0'69 A.U. Mean displacement 

 per atmosphere = approximately 

 4'5 thousandths of an A.U. 



Immense unsymmetrical broadening. 

 Displacement approximately 



1 1 A.U. Mean per atmosphere 

 = 0-007 A.U. 



Immense unsymmetrical broadening. 

 Displacement approximately 



97 A.U. Mean per atmosphere 

 - 0-0063 A.U. 



Considerably broadened. Fairly 

 compact. 



Immense unsymmetrical broadening. 



Immense unsymmetrical broadening. 

 Displacement 0'83 A.U. Mean 

 per atmosphere = 0-0054 A.U. 



Immense unsymmetrical broadening. 



Immense unsymmetrical broadening. 

 Displacement - 91 A.U. Mean 

 per atmosphere = 006 A.U. 



Merged into 190 or else vanished. 



200 atmospheres. 



Immensely broadened. Unsym- 

 metrical to red. Displacement 

 between 0-71 and 0'91 A.U. 

 Mean displacement per atmosphere 

 between 3 5 and 4 5 thousandths 

 of an A.U. 



Faint hazy patch of luminosity. 

 Flat-topped intensity curve. 



Immensely broadened. Displace- 

 ment between 0'9 and 1'G A.U. 

 Mean displacement per atmosphere 

 = approximately 6 thousandths 

 of an A.U. 



Immense unsymmetrical broadening. 



Immense unsymmetrical broadening. 

 Displacement approximately 



1-7 A.U. Mean per atmosphere 

 = 0-0085 A.U. 

 Not quite merged in background. 



Faint hazy patch of luminosity. 



Immense unsymmetrical broadening. 

 Displacement (1"9) A.U. Mean 

 per atmosphere = (0'0095) A.U. 

 Faint patch of luminosity. 



Immense unsymmetrical broadening. 



Displacement 0-97 to 1-9 A.U. 

 Mean per atmosphere = 0-005 



to 0-009 A.U. 



Merged or vanished. 





(4) Displacement towards the Violet : The writer has on previous occasions 

 chronicled the displacement of a few lines towards the more refrangible part of the 

 spectrum and so have other observers. In the nickel spectrum similar displacements 

 have been recorded, and it will be seen from the following table that there is good 

 agreement between the readings made by my assistant and myself upon these lines. 

 In accordance with precedent Mr. PE ARSE'S determinations are those which are included 

 in Diagram 5, where the negative displacements are distinguished by a horizontal line 

 passing through the dot. It would be of great interest to observe if the displacement 

 towards the violet increases or decreases with increase of pressure, but unfortunately 

 reliable measurements of the displacements of these lines were not feasible above 

 a pressure of 10 atmospheres. The reality of displacements towards the violet 



