The work was at first carried on with great secrecy, lest other makers should copy the art; and the precaution was taken of stopping the keyhole of the workshop-door while the casting was in progress.

To secure himself against piracy, he proceeded to take out a patent for the process in the year 1708, and it was granted for the term of fourteen years.

The recital of the patent is curious, as showing the backward state of English iron-founding at that time.

It sets forth that "whereas our trusty and well-beloved Abraham Darby, of our city of Bristol, smith, hath by his petition humbly represented to us, that by his study, industry, and expense, he hath found out and brought to perfection a new way of casting iron bellied pots and other iron bellied ware in sand only, without loam or clay, by which such iron pots and other ware may be cast fine and with more ease and expedition, and may be afforded cheaper than they can be by the way commonly used; and in regard to their cheapness may be of great advantage to the poor of this our kingdom, who for the most part use such ware, and in all probability will prevent the merchants of England going to foreign markets for such ware, from whence great quantities are imported, and likewise may in time supply other markets with that manufacture of our dominions, &c.....

grants the said Abraham Darby the full power and sole privilege to make and sell such pots and ware for and during the term of fourteen years thence ensuing." Darby proceeded to make arrangements for carrying on the manufacture upon a large scale at the Baptist Mills; but the other partners hesitated to embark more capital in the concern, and at length refused their concurrence.