But the "voragious iron-mills" were proceeding to swallow up everything that would burn, and the old forest growths were rapidly disappearing.

An entire wood was soon exhausted, and long time was needed before it grew again.

At Lamberhurst alone, though the produce was only about five tons of iron a-week, the annual consumption of wood was about 200,000 cords! Wood continued to be the only material used for fuel generally--a strong prejudice existing against the use of sea-coal for domestic purposes.[11] It therefore began to be feared that there would be no available fuel left within practicable reach of the metropolis; and the contingency of having to face the rigorous cold of an English winter without fuel naturally occasioning much alarm, the action of the Government was deemed necessary to remedy the apprehended evil.
To check the destruction of wood near London, an Act was passed in 1581 prohibiting its conversion into fuel for the making of iron within fourteen miles of the Thames, forbidding the erection of new ironworks within twenty-two miles of London, and restricting the number of works in Kent, Surrey, and Sussex, beyond the above limits.

Similar enactments were made in future Parliaments with the same object, which had the effect of checking the trade, and several of the Sussex ironmasters were under the necessity of removing their works elsewhere.
Some of them migrated to Glamorganshire, in South Wales, because of the abundance of timber as well as ironstone in that quarter, and there set up their forges, more particularly at Aberdare and Merthyr Tydvil.

Mr.
Llewellin has recently published an interesting account of their proceedings, with descriptions of their works,[12] remains of which still exist at Llwydcoed, Pontyryns, and other places in the Aberdare valley.