190 RAILWAY CONSTRUCTION. 



The experience obtained year after year in the wear of rails 

 under heavy traffic, led to continued improvements both in the 

 method of rolling and in the selection of the iron to form the 

 rail-pile; one description of iron was found more suitable for 

 the head, or running surface, and another for the vertical web ; 

 but, even with the best machinery and most carefully assorted 

 materials, high-class wrought-iron rails were liable to lamination, 

 and long thin strips of iron became detached from the upper, or 

 wearing, surface. The rail was composed of many layers of iron, 

 and it was not always possible to ensure that they were all 

 thoroughly welded, or incorporated together. As early as 1854 

 a few experimental solid steel rails were laid down on some of 

 the principal railways, and gave excellent results as to evenness 

 of wear and durability, but their cost of manufacture rendered 

 their extended use almost prohibitory. 



Compound rails of steel and wrought-iron, as in Fig. 260, 

 were also tried on several railways, but the practical results 

 were not such as to lead to a very extended adoption. In 

 preparing the pile for a compound rail, suitable wrought-iron 

 bars were placed to form the lower member or flange, the web. 

 and part of the head, and a slab of steel was placed on the top 

 to form the upper portion of head, or wearing surface of the 

 rail. It was intended that in the process of rolling these distinct 

 layers were to be incorporated together, to form the section 

 shown in Fig. 260. Doubtless many good wearing rails were 

 manufactured on this system, but the inherent difference of the 

 two materials, steel and iron, rendered it very difficult to ensure 

 such uniform incorporation as would withstand the constant 

 pounding under heavy, fast traffic. It was not until some years 

 later that the process of the Bessemer Converter was discovered 

 and perfected, by means of which steel can be produced in large 

 quantities far more rapidly and at much less cost than by any 

 other method hitherto adopted. The introduction of this process 

 for making steel caused a complete revolution in the material 

 for rails. Steel which had previously been excluded on account 

 of its cost, could now be supplied at a moderate price, and, 

 from its compact and homogeneous character, promised a very 

 much longer wearing life than the best wrought-iron rails 

 that had ever been rolled. Experience has shown that these 

 promises have been fully verified ; wrought-iron rails are things 

 of the past, steel rails have taken their place, and can now be 



