English: In 1820, Mr. Birkinshaw patented an improvement in the form of hammered iron rail. The malleable iron rails previously used were bars from two to three feet long, and one to two inches stjuare ; but either the narrowness of the surface produced such injury to the wheels, or by increasing the breadth their cost became so great, as to exceed that of cast iron, which consequently was preferred.

It was to remedy these defects in the malleable form, and at the same time to secure the same strength as the cast iron, that Mr. Birkinshaw made his rails in the form of prisms, or similar in shape to the cast-iron ones of the most approved character. fig. 578 shows a side view of this kind of rail; jig. 579 a plan, and fig. 580, a section of the same rail cut through the middle.

These rails are made by passing bars of iron, when red hot, through rollers with indentations or grooves in their peripheries, corresponding to the intended shape of the rails ; the rails thus formed present the same surface to the bearing of the wheels, and their depths being regulated according to the distance from the point of bearing, they also present the strongest form of section with the least material.