138 
Transactions of the Society. 
Name of Glass. 
Z 
B 
E 
1 
F 
G* 
Hi 
Hard crown . . 
•0035410 
•0029186 
•0052525 
•0088588 
•0120192 
Soft crown 
•0037149 
•0030620 
•0055105 
•0092939 
•C126095 
Extra light flint . . 
•0046471 
•0038303 
•0068933 
•0116260 
•0157737 
Light flint 
•0055737 
•0045941 
•0082679 
•0139443 
•0189190 
Dense flint . . 
•0068649 
•0056583 
•0101831 
•0171745 
•0233016 
Extra dense flint . . 
•0076566 
•0063108 
•0113575 
•0191551 
•0259888 
Double extra dense! 
flint ( 
•0093763 
•0077283 
•0139084 
•0234574 
•0318260 
Errors in Calculated Values. 
Name of Glass. 
B 
E 
F 
G' 
Hard crown .. 
- *14 
- *30 
- *28 
+ *01 
+ *23 
Soft crown 
- *13 
- *85 
- *66 
- *69 
- fl04 
Extra light flint .. 
- *18 
- *23 
+ *07 
+ *80 
+ *61 
Light flint 
- *45 
- *72 
- *12 
+ *99 
+ tl23 
Dense flint 
- *61 
- *90 
- *51 
+ *60 
+ *28 
Extra dense flint .. 
- *65 
- fill 
- *85 
+ *90 
- *01 
Double extra dense) 
flint [ 
- *89 
- *51 
+ *19 
+ f266 
t=-000 *=*0000 
