OF NITRO-CELLULOSE AND THE LAW OF ITS OPTICAL BEHAVIOUR. 161 
obtained from spectrum observations gives the following values, of which Table VI. 
is a typical example, from which the mean values are obtained as follows :— 
Strains. 
0-001 
0-002 
0-003 
0-004 
0-005 
0 006 
0-007 
0-008 
Stresses in lbs. per sq. 
inch. 
310 
620 
920 
1240 
1540 
1845 
2135 
2400 
Strains. 
0 • 009 
o-oio 
0-011 
0-012 
0-013 
0-014 
0-018 
0-0192 
Stresses in lbs. per sq. 
inch. 
2G65 
2890 
3055 
3285 
3460 
3680 
4310 
4455 
Table of mean values 
Fig. 16. Comparison of stress-strain curves. 
