But when the sons had grown up to manhood, they too entered upon the business of iron-founding; and Abraham Darby's son and grandson, both of the same name, largely extended the operations of the firm, until Coalbrookdale, or, as it was popularly called, "Bedlam," became the principal seat of one of the most important branches of the iron trade.
There seems to be some doubt as to the precise time when pit-coal was first regularly employed at Coalbrookdale in smelting the ore.

Mr.
Scrivenor says, "pit-coal was first used by Mr.Abraham Darby, in his furnace at Coalbrookdale, in 1713;" [4] but we can find no confirmation of this statement in the records of the Company.

It is probable that Mr.Darby used raw coal, as was done in the Forest of Dean at the same time,[5] in the process of calcining the ore; but it would appear from his own Memoranda that coke only was used in the process of smelting.
We infer from other circumstances that pit-coal was not employed for the latter purpose until a considerably later period.

The merit of its introduction, and its successful use in iron-smelting, is due to Mr.
Richard Ford, who had married a daughter of Abraham Darby, and managed the Coalbrookdale works in 1747.

In a paper by the Rev.Mr.Mason, Woodwardian Professor at Cambridge, given in the 'Philosophical Transactions' for that year,[6] the first account of its successful employment is stated as follows:--"Several attempts have been made to run iron-ore with pit-coal: he (Mr.Mason) thinks it has not succeeded anywhere, as we have had no account of its being practised; but Mr.
Ford, of Coalbrookdale in Shropshire, from iron-ore and coal, both got in the same dale, makes iron brittle or tough as he pleases, there being cannon thus cast so soft as to bear turning like wrought-iron." Most probably, however, it was not until the time of Richard Reynolds, who succeeded Abraham Darby the second in the management of the works in 1757, that pit-coal came into large and regular use in the blasting-furnaces as well as the fineries of Coalbrookdale.
Richard Reynolds was born at Bristol in 1735.