90 Mr Purvis, The influence of very strong 



With regard to the lines divided into triplets, of the lines 

 4061-5, 4057-5, 3738-9, 3682-9, 36392, 3572-6, 2832'2, 2801-4, the 

 two outside members vibrate perpendicular, and the inner one 

 parallel, to the lines of force. On the other hand, of the triplets 

 arising from 2662'5 and 2613'4, the two outside members vibrate 

 parallel, and the inner one perpendicular, to the lines of force. 



Tin. 



Wave-length 



\ 4524'0. The line becomes a triplet, the two outer members of which 



vibrate perpendicular to the line of force, and the inner 



one parallel thereto. 

 3800 - 3. There is a distinct widening, and, when analysed by the 



calcite, it seems to be a triplet, with the two outside 



components vibrating perpendicular, and the inner one 



parallel, to the lines of force. 

 3655*5. The line is widened, but the image is too weak to analyse. 

 3351 '8. A nebulous band, which seems to be very slightly widened. 



No separation can be made out by the calcite. 

 3330'0. This line becomes a doublet or reversal. The separation is 



clear, sharp and well defined. 

 3282*9. A nebulous band, which seems to be very slightly widened. 



No separation can be made out by the calcite. 

 3261-6. The line becomes a triplet, and the two outside members 



vibrate parallel, and the inner one perpendicular, to the 



lines of force. 

 3174 # 3. This line becomes a triplet, with the two outer components 



vibrating parallel, and the inner one perpendicular, to 



the lines of force. 

 3033T. This becomes a triplet, with the two outer members 



vibrating perpendicular, and the inner one parallel, to 



the lines of force. The three components, when analysed 



by the calcite, do not appear so well defined nor so sharp 



as in other instances. 

 3007*9. This is a triplet, with the members vibrating as in 3033T. 



And also here the components separated by the calcite 



are not so well defined, although the definition is sharper 



than that of 3033 1. 

 2862 T. This line becomes a triplet, the two outer components 



vibrating perpendicular, and the inner one parallel, to 



the lines of force. 

 2849 "3. A somewhat weak line, which is widened. The separation 



is not very well defined, but it seems to be a triplet, 



with the two outer members vibrating perpendicular, 



and the inner one parallel, to the lines of force. 

 2838*9. This becomes a triplet, with the components vibrating as 



the last. 

 2705 "8. There is a well-marked widening, but the line is too weak 

 to analyse with the calcite. 



