The early history of iron making in Scotland is obscure but it seems that despite a lack of self-sufficiency in the early modern period, reflected in trade with England and overseas countries going back to the fifteenth century, there were a large number of bloomeries, perhaps as many as 2,000. Some were situated in an exposed position to benefit from strong winds while others achieved greater efficiency through harnessing water power. Bog ore was acceptable, with an open porous structure amenable to smelting with charcoal from forests and peat mosses. These resources gave some prominence to the Highlands as a potential exporter to other parts of the country and there is a hint of such a dimension in the decision of George Hay (entrepreneur of the Wemyss glass works in Fife) to build a furnace at Letterewe (Ross & Cromarty) in 1607. It is known that the iron was of good quality, taking advantage of the expertise of some English workers employed in smelting and casting and from the use of some haematite ore from Furness, and also that Hay's influence at court exempted the works from the prohibition on the use of timber for smelting in 1609. But the ultimate fate of the venture is unknown and the most reasonable assumption is that it closed on the expiry of the nineteen year lease. Further efforts were made in the Highlands in the eighteenth century with the York Buildings Company leading the way with their project for Glenkinglass near Loch Etive (Argyll & Bute) in 1725.