gg DR. W. GEOFFREY DUFFIELD ON THE 



ataMVto*. it remains a definite line, but has broadened (about 0*5 A.U at 

 25 Atmospheres) and is displaced. At 80, 100, 120, and 200 atmospheres the 

 photographs show no trace of its presence. 



(<) 4212*1. Silver. 1st subordinate series. 



At normal atmospheric pressure it is broad and covers 16 to 20 A.U. (according to 

 the amount of exposure). It is asymmetrically reversed, its reversed portion being 

 slightly on the red side of the centre of the bright line, thus differing from a (4055-44), 

 the other member of the 1st subordinate series. At 5 and 20 atmospheres its 

 behaviour strongly resembles that of line a ; it has broadened and is distinguishable 

 60 A.U. from its original position ; the reversal which is just visible is displaced 

 towards the red end of the spectrum. The wings are shaded into a number of lines, 

 which are, however, differently spaced from those into which line a, is resolved. 

 Bettveen 25 and 200 atmospheres, this line cannot be distinguished from the 

 banded or continuous spectrum which in this region takes the place of the line 

 spectrum of silver. 



(d) 431T28. Non-series line.* 



At normal atmospheric pressure the line is fairly sharp, being only slightly 

 broadened towards the red. At 5 and 20 atmospheres it is seen to be slightly 

 broadened towards the red, though it is still comparatively sharp ; its displacement 

 towards the same end of the spectrum is also obvious. At 25 atmospheres the line 

 appears to be the violet head of a band stretching some distance towards the red. 

 At 60 and 80 atmospheres the line at ordinary atmospheric pressure seems to mark 

 the violet edge of the band, which becomes less sharp and less obvious as the pressure 

 is increased. It is now doubtful if the band to the right of the line has any causal 

 connection with it. Between 100 and 200 atmospheres, this band has become 

 submerged in the continuous spectrum that now dominates the photograph. . 



(e) 4476-29. Member of the 2nd subordinate series. 



At normal atmospheric pressure it is broadened towards the red. At 5 and 20 

 atmospheres its width has increased and it has suffered displacement towards the red 

 end of the spectrum. At 25 atmospheres it can still be distinguished, though its 

 intensity has been greatly reduced. Its displacement, though large, is difficult to 

 At 60, 80, and 100 atmospheres no sign of this line appears, though, if any 

 radiation of a period close to its original period existed, it should be visible, because the 



here were three slit* in the comparison shutter where this line occurs, so that three small pieces of 

 c pressure appeared upon the photograph. Two of them may be seen on the 

 atmospheres. They permit the comparison line to be easily placed parallel to the 

 iMe crow-wires in the measuring machine. 



