Bass's eagerness to explore soon found other scope. In 1797, report was brought to Sydney by shipwrecked mariners that, in traversing the coast, they had seen coal. He at once set off to investigate. At the place now called Coalcliff, about twenty miles south of Botany Bay, he found a vein of coal about twenty feet above the surface of the sea. It was six or seven feet thick, and dipped to the southward until it became level with the sea, "and there the lowest rock you can see when the surf retires is all coal." It was a discovery of first-class importance--the first considerable find of a mineral that has yielded incalculable wealth to Australia.* (* It is well to remember that the use of coal was discovered in England in very much the same way. Mr. Salzmann, English Industries of the Middle Ages, 1913 page 3, observes that "it is most probable that the first coal used was washed up by the sea, and such as could be quarried from the face of the cliffs where the seams were exposed by the action of the waves." He quotes a sixteenth century account relative to Durham: "As the tide comes in it bringeth a small wash sea coal, which is employed to the making of salt and the fuel of the poor fisher towns adjoining." Hence, originally, coal in England was commonly called sea-coal even when obtained inland.) He made this useful piece of investigation in August; and in the following month undertook a journey on foot, in company with Williamson, the acting commissary, from Sydney to the Cowpastures, crossing and re-crossing the River Nepean, and thence descending to the sea a few miles south of his old resting place, Watta-Mowlee. His map and notes are full of evidence of his careful observation. "Tolerably good level ground," "good pastures," "mountainous brushy land," and so forth, are remarks scored across his track line. But these were pastimes in comparison with the enterprise that was now occupying his mind, and upon which his fame chiefly rests. Hunter's despatch to the Duke of Portland, dated March 1st, 1798, explains the circumstances of the expedition leading to the discovery of Bass Strait: "The tedious repairs which His Majesty's ship Reliance necessarily required before she could be put in a condition for going again to sea, having given an opportunity to Mr. George Bass, her surgeon, a young man of a well-informed mind and an active disposition, to offer himself to be employed in any way in which he could contribute to the benefit of the public service, I enquired of him in what way he was desirous of exerting himself, and he informed me nothing would gratify him more effectually than my allowing him the use of a good boat and permitting him to man her with volunteers from the King's ships. I accordingly furnished him with an excellent whaleboat, well fitted, victualled, and manned to his wish, for the purpose of examining the coast to the southward of this port, as far as he could with safety and convenience go."