In 1517 an entry in the State Papers Domestic, given on page 31, states that 2541 lb. of Isebroke steel cost £26 12s., which gives about £23 for the ton. In the _Sussex Archæological Journal_, II, 200, Walter Burrel gives an account of Sussex ironworks in the seventeenth century. He states that when once the furnace was lit it was kept going sometimes for forty weeks, the period being reckoned in “foundays.” During each founday eight tons were made with twenty-four loads of charcoal. The metal was cast into “sows” weighing from 600 to 2000 lb. He states that “they melt off a piece of the sow about three quarters of a hundredweight and beat it with sledges near a fire so that it may not fall to pieces, treating it with water they thus bring it to a ‘bloom,’ a four square piece 2 ft. long.”[62] Modern bar-iron 1 in. by 1 in. by 12 in. weighs 3.4 lb. Therefore this bloom would approximately make a plate 33 sq. ft. by 1/16 in. thick.[63] Even with these data it is impossible to tell the size of the plates delivered to the armourer; for the appliances in the Middle Ages were but crude, and it is doubtful if rolling-mills were used in the sixteenth century. From the picture by Breughel, given as the frontispiece, we know that tilt-hammers were in use, but these would hardly have been used to flatten plates of any great size. It would appear that iron in some localities was tainted with some poison; for in a _Géographie d’Edrisi_ quoted in _Gay’s Encyclopædia_, 699, reference is made to a mountain in Armenia where the iron ore is poisoned and which, when made into knives and swords, produced mortal wounds. It may have been that this was actually the case, but it is more probable that it was an invention of the owner of the mine designed to give his productions a fictitious value. A few details of interest in connection with the manufacture of iron in England may be gathered from the _Metallum Martis_ of Dud Dudley, a natural son of Edward, Lord Dudley. The treatise was printed in 1665 and refers to the author’s endeavours to interest the Crown in his project for smelting iron with sea-coal instead of wood or charcoal. In his address to the King (Charles II) and Council he prefaces his technical remarks as follows:--