212 MR W. GORDON AND MR G. H. GULLIVER ON 
represent the original and the final area, respectively. The values of this quantity 
are given in Table VIII., and a curve showing its variation with the ratio width/ 
thickness is drawn in fig. 13. The curve is of the same form as that of fig. 6, the 
curve of maximum extension at fracture, the two quantities being related thus :— 
dd 
at 
Maximum extension, 
TABLE VIII. 
Repuction or AREA, AND Maximum EXTENSION AT FRACTURE. 
Nominal Widen, |) Wadube Reduction ote Aren Mes es 
Inches. Thickness — Per cent. Pox coat ; 
1 1-76 64:1 178-7 
] 3-81 59°5 147°8 
| A 5-64 56 2 1279 
24 9°57 56-2 128°8 
3 11:14 54:0 et 
3h 13325 56-0 127°3 
4 15:39 54-7 120°8 
The method of determining the final area has been described already, and the diffi- 
culty of securing accuracy has been mentioned. In the neighbourhood of fracture the 
section of a bar initially rectangular is not a rectangle, but has curved sides, the curva- 
ture being less pronounced the wider the bar. Moreover, the ratio of width/thickness does 
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WIDTH 
THICKNESS 
Fic, 14.—Change in the ratio of width to thickness of flat steel test-pieces after fracture. The upper curve shows the increas 
in the ratio at the fracture itself, and the lower one the increase in the sensibly parallel portion of the bar. 
not remain constant but increases during extension ; in other words, the metal is reduce 
relatively more in thickness than in width, a result quite to be expected. Similarly the 
width is reduced less in the wide than in the narrow bars, even when compared with 
the diminished thickness. ‘The values of the final ratio of width to thickness are give’ 
