442 MR. J. E. H. GORDON ON MEASUREMENTS OF ELECTRICAL CONSTANTS. 
Refractive index of double extra-dense flint glass. 
Specific gravity 
4 - 421 Gordon. 
4-42162 Hopkinson. 
•v/K= 17783. 
Ray. 
"Wave length. 
fi. 
Ray. 
Wave length. 
GrOEDOX. 
Hopkinson. 
Bright line in extreme red . 
D. 
h . 
\ . 
Bright line in central blue . 
Band in extreme violet . 
5-892 
| 5-174 | 
1-7032 
1-7099 
1-7201 
1-7234 
1-7374 
1-7460 
1-7011 
1-7102 
j 1-7209 
1-7272 
/ 1-7432 
{ 1-7577 
B 
D 
b 
F 
G 
Hj 
6-867 
3-968 
Which give /r A=00 
1"655 Gordon from D and b. 
1 -672 Hopkinson from B and H^ 
Refractive index of extra-dense flint glass. 
.p f 3-884 Gordon. 
fepccinc \ 
13-88947 Hopkinson. 
v / K=1 , 7474. 
Ray. 
Wave length. 
/i. 
Ray. 
Wave length. 
Gobdon. 
Hopkinson. 
Bright line in extreme red . 
1-6423 
1-6429 
B 
6-867 
D. 
5-892 
1-6478 
F6505 
D 
. 
b 2 . 
J 5-174 | 
1-6561 
1-6586 
| 1-6591 
b 
Bright line in central blue . 
1-6693 
J 1-6642 
F 
Band in extreme violet . 
1-6757 
/ 1-6770 
1 1-6885 
G 
3-968 
Which give /r A=ao = 
1-615 Gordon from D and b. 
1-620 Hopkinson from B and Hj. 
