214 THE STRENGTH AND DUCTILITY OF FLAT STEEL BARS. 
difference of extension is only 2 per cent. on the gauge-leneth, that is, about one- 
fourteenth of the extension of the narrowest bar. 
The extension on other variable gauge-lengths proportional to area changes in a 
somewhat similar manner. 
(5) The reduction of area decreases as the ratio width/thickness is increased from 
2 to 6, and then remains sensibly constant. 
(6) The thickness of a flat bar is reduced relatively more than the width, and the | 
width of a narrow bar is reduced relatively more than that of a wide one. 
(7) The critical ratios of width to thickness are not strongly marked, and probably § 
vary with the absolute thickness of the bar, and with the quality of the metal. 
In conclusion, the thanks of the authors are due to Prof. Hudson Beare for the 
facilities accorded, and for the interest which he has shown in the work. <a 
REFERENCES. 
(1) Publications of the Engineering Standards Committee, No. 18, Crosby Lockwood, London, 
June 1907. : 
(2) Barsa, Commission des Méthodes d’ Essai des Matériaux de Construction, Rothschild, Paris, 1895, 
Ti WAS: 
(3) AppLepy, Proc. Inst. Civ. Eng., 1894, exviii., 395. : 
(4) Unwin, Proc. Inst. Civ. Eng., 1903, clv., 170. 
(5) Guuutver, Proc. Inst. Mech. Eng., 1905, 141, and 1907, 519. 
j 
Abi 
