THE STRENGTH AND DUCTILITY OF FLAT STEEL BARS. 199 
mtinued over the middle 12 inches of the length, in order that the extension might 
be computed in a satisfactory manner. The width and thickness of each bar were 
rmined by a micrometer to ‘001 inch; the maximum variation in dimensions did 
Fic. 2.—Longitudinal section of soft steel plate containing 0°12 to 0°15 per cent, of 
carbon ; etched with picric acid and sodium picrate ; magnified 100 diameters. 
cceed 0°5 per cent. In Table II. are given, averaged for each set of bars, the 
sectional dimensions and area, the square root of the area, and the ratio of 
h to thickness. 
TABLE II. 
DIMENSIONS OF TEST-BARS. 
nal Width. | Actual Width. Thickness. Area. Nem Width 
Inches. Inch. Sq. inches. ares Thickness" 
0-450 0°255 07115 0°339 1°76 
0°967 0:254 0°245 0-495 3°81 
1-443 0°256 0°370 0-608 5°64 
1-947 0°257 0°501 0-708 T5T 
2-478 0259 0642 0-801 9°57 
2°897 0:260 0-752 0867 11:14 
3°451 0:259 0-894 0°945 13°32 
3°955 0:257 1:016 1-008 15°39 
The bars from } inch to 3 inches wide were tested in the Riehlé (gear-driven) 
une, and those 34 and 4 inches wide in the Buckton (hydraulic) machine of the 
ineering Department of the University of Edinburgh. When setting the bars in 
testing machine, the centre line of one face was plumbed so that the load should be 
