OP GLASS, AND THE EESISTANCE OF GLASS VESSELS TO COLLAPSE. 247 
lY. Resistance of Rectangular Glass Bars to a Transverse Strain. 
Let I — the length of the bar supported at the ends and loaded in the middle. 
W = breaking weight in lbs. 
K = area of the whole transverse section. 
D = the whole depth of the section. 
= the respective distances of the top and bottom edges from the neutral axis. 
Ti = the tensile resistance of the material in lbs. per square inch. 
Ta = the compressive resistance of the material in lbs. per square inch. 
Then we have “Tate’s strength of material” equations (27.) and (6.) — 
hence we get 
where the constant 
and.^;==:^; 
W-4 T,-T, K.D K.D 
I I ■ 
T,.T, _ 4 2560x30150 
3-Tj + T2~3 X 32710 —3140 nearly. 
( 17 .) 
Substituting this value of the constant, equation (16.) becomes 
W=3140.~, (18.) 
which expresses the transvei’se strength of a rectangular bar of glass supported at the 
ends and loaded in the middle. 
2 L 2 
