66 IRON AND STEEL. 



notches or furrows upon their surfass) by the force of my engine 

 hereafter described, or other power, into such shapes and forms as 

 shall be required." In this document we have a faithful description 

 of grooved rolls, and also an account of the decarbonization of cast 

 iron in a reverberatory furnace — that is a process of puddling iron, 

 instead of reducing it to nature by the slow 'and expensive process 

 of repeated heatings and hammerings, as had theretofore been 

 practiced. 



Another candidate for the honor of having invented rolls was 

 Major John Hanbury, who professed to have made the discovery in 

 1729, a year after Payne's patent was granted. About 1680 Andrew 

 Yarranton was sent into Saxony to learn the art of coating iron with 

 tin. The knowledge of that process is said to have been carried into 

 Saxony from Bohemia by a clergyman, but its origin is lost. Yarran- 

 ton succeeded in his mission, and brought the art into England, 

 where the manufacture of tinned plates soon assumed considerable 

 proportions, not only for home use, but for export. After the intro- 

 duction of rolls the English plates were considered superior to those 

 made on the continent, because they were rolled and not hammered, 

 and were consequently of equal thickness throughout. 



A great impetus was given to the iron trade in England by the 

 labors of Henry Cort toward the close of the 18th century. He 

 greatly improved the rolls and brought them into general use ; and 

 he perfected the process of puddling, bringing it substantially to its 

 present perfection. It will be remembered that the product of the 

 low bloomary was malleable iron. The carbon in the fuel was all 

 burned away by a strong blast of air directed through the tuyeres 

 upon the bloom as it formed. The process was slow and expensive, 

 though it is to be noted that bloomaries only slightly improved are in 

 use to-day and produce high grade malleable iron of first rate quality 

 in competition with modern furnaces. When the high furnace was 

 introduced it made the first production of iron much cheaper, but the 

 iron was cast iron, and the expense of converting it into malleable 

 iron in the finery was tedious and costly. Cort by the puddling 

 furnace made the operation simple and very much cheaper. 



Another highly important improvement introduced into England 

 about the middle of the eighteenth century was the substitution of 

 mineral fuel for charcoal. The attempt had been made a centnry 



