488 
Mr Filon, On the variation with the wave-length 
Feb. 24 
Feb. 25 
y(n+l) _ y(n) 
in cms. 
\ in tenth- 
metres 
(Cp)- 1 
y(n+l) _ y(n) 
in cms. 
\ in tenth- 
metres 
(Cp)- 1 
•670 
6250 
1070 
•693 
6440 
1077 
•645 
6040 
1070 
•657 
6210 
1057 
•615 
5860 
1050 
•623 
6000 
1039 
•595 
5690 
1045 
•615 
5830 
1055 
•570 
5530 
1030 
•595 
5650 
1053 
•555 
5390 
1030 
•575 
5500 
1045 
•540 
5260 
1025 
•560 
5360 
1045 
•525 
5140 
1020 
•550 
5240 
1050 
•510 
5030 
1015 
•535 
5120 
1045 
•495 
4930 
1005 
•515 
5010 
1028 
•485 
4830 
1005 
•505 
4910 
1029 
•475 
4740 
1000 
•495 
4810 
1029 
•470 
4650 
1010 
•490 
4720 
1038 
•462 
4570 
1010 
•480 
4630 
1037 
•452 
4490 
1005 
•473 
4550 
1040 
•448 
4430 
1010 
•460 
4480 
1027 
•436 
4370 
1000 
•454 
4420 
1027 
•430 
4310 
1000 
•450 
4360 
1032 
•424 
4260 
995 
•442 
4300 
1028 
•414 
4200 
985 
•440 
4250 
1035 
•410 
4150 
990 
•426 
4190 
1017 
•406 
4100 
990 
•418 
4140 
1010 
•400 
4060 
985 
