ON THE MECHANICAL PROPERTIES OF STEEL. 



147 



A wrought-iron girder of the same dimensions would break with 11-8 

 tons. The comparison, therefore, stands as lS-1: 11-8, being in the ratio 

 of 1 : -652. The resistance of this description of steel to a transverse strain 

 is therefore more than one and a half times greater than that of wrought 

 iron. 



Experiment on a Steel Girder from the Barrow Haematite Steel 

 Company (April 1868). 



Length between supports 13-9 feet. Sectional area 2-31 inches. 



There is great difficulty in testing beams of this description, arising from 

 the narrow top and bottom flanges, which, to prevent injury from lateral 

 flexure, should be loaded and broken through the sides of a rigid frame. In. 

 this case the beam was identical in every respect with the previous one, and 

 would have carried the same weight but for the lateral injuries it received in 

 the early stages of the experiment. Taking, however, the strength of steel 

 beams and the amount of deflection when submitted to a transverse strain, 

 it will be found that they are not only one-third stronger than those of the 

 best wrought iron, but they are much superior in their powers to resist im- 

 pact, and therefore more secure under the influence of a rolling load or 

 severe vibratory action often repeated. 



Taking into account the peculiar properties of this material, its superior 

 strength, the saving of one-third in weight, and other conditions of security, 

 it is (under the conditions of perfect uniformity of character in the manufac- 

 ture) admirably adapted for roUed joists and gii-ders, as also for bridges, 

 where high powers of strength and elasticity are required to resist the united 

 forces of load and impact. 



Appendix II. 



The ' Practical Mechanics' Journal ' gives the following description of the 

 furnace and apparatus for the manufacture of steel on the Heaton system. 

 See Plate II. :— 



The Heaton converter (fig. A) is nearly a cylindrical cupola, lined with 4^- 

 inch iire-brick, the shell of boiler plate, and surmounted by a plate-iron coni- 

 cal cap and narrower cylindrical flue of a few feet in height. The cupola may 

 be supposed cut in two horizontally at about one diameter and a half in height, 



l2 



