232 
MR. W. H. BARLOW ON THE RESISTANCE OF FLEXURE 
In connexion with the above-described experiments, I made four others on solid 
beams having the same sectional area and length as the open girders ; and the mean 
of the four gave a breaking weight of 1888 lbs. Obtaining the value of F from these 
experiments, we have, — 
Deflection with nine-tenths 
of breaking weight. 
Value of F. 
•670 
41709 lbs. 
which again exhibits an increase in the value of F, with an increase in the deflection. 
The foregoing experiments having shown that in girders containing the same depth 
of metal, the resistance arising from the lateral action of the particles depended on 
the amount of the flexure, I thought it desirable to make other experiments to 
ascertain how this resistance varied in girders having the same total depth, and con- 
sequently nearly the same deflection, but with different depths of metal in the girder. 
For this purpose beams were cast of the forms Nos. 5, 6 and 7 , each 4 inches deep, 
and with the upper and lower ribs 1^ inch by f inch, the ribs being placed as 
shown in the figures, so that the depth of the metal in No. 5 was twice as great as 
in Nos. 6 and 7- 
Four beams were cast of each form, — the exact dimensions and breaking weights 
are given in the Appendix, — and the mean results were as follows : — 
Description of beam. 
Depth of beam. 
Depth of metal. 
Sectional area. 
Deflection. 
Breaking weight. 
Form No. 5 
4-04 
3-01 
2-320 
•322 
5141 
Form No. 6 
4-04 
1-48 
2-230 
•310 
6147 
Form No. 7 
4*07 
1*56 
2-380 
•262 
6000 
Obtaining the value of F from these experiments, and comparing them with beam 
No. 4, which had the same total depth, we have — 
Deflection. 
Depth of 
metal. 
Value of F. 
Form No. 5 
•322 
3-01 
37408 
Form No. 4 
•301 
1-97 
28032 
Form No. 7 
•262 
1-56 
27908 
Form No. 6 
•310 
1-48 
25271 
These experiments did not affbrd so complete a comparison as the former series, 
because the intervals between the vertical ribs were not equal, nor in the same pro- 
portion to the depth of metal, the effect of which would be to vary to some extent 
the form of the curve of deflection. Nevertheless, they show in an equally decided 
manner, that when the deflection is the same the resistance increases when the depth 
of metal in the beam is increased. 
The foregoing experiments have therefore elicited three facts as regards beams 
formed of two parallel bars separated at given intervals by vertical ribs : — 
