Running down the coast, on the 7th January he entered the great bay, then called Bahia Sin-fondo, or San Matthias' Bay, but now more generally known under the name of San Antonio, at the bottom of which, in latitude 42° 13´, he discovered the entrance of a noble harbour, which he named San Joseph's.

Piedra passed three months in examining the shores of this great gulf and the peninsula which bounds it, and so impressed was he with its capabilities that, without proceeding further, he left an officer and part of his men to build a fort there, and returned himself to the River Plate to give an account of his discovery.

According to his report, indeed, it appeared on many grounds to offer a most eligible site for a new settlement. The port itself was said to be deep and commodious, affording anchorage for ships of any size, whilst its situation seemed particularly convenient not only for facilitating the further exploration of the great rivers Negro and Colorado, which empty themselves a little to the northward of it, but for securing more or less the entrance of those rivers against any sudden surprise by the enemies of Spain, a point to which great importance was attached in the instructions of the surveying officers, in consequence of the statements made by Falkner as to the possibility of passing up them into the very heart of the Spanish possessions.

The vast number of whales and seals which were seen in its neighbourhood, moreover, held out the promise of its becoming a station whence to carry on those fisheries which the Spanish Government of the day were so anxious to establish[19]; whilst the extensive salt deposits in several parts of the peninsula promised an inexhaustible supply of an article of the first necessity in Buenos Ayres in curing the hides and beef.

The only drawback to the situation was the apparent scarcity of fresh water, which the discoverers had great difficulty in finding in the first instance, though subsequently a sufficiency was obtained at some distance from the coast: it was, however, at all times more or less brackish, and eventually caused much sickness and suffering to the settlers.

The Viceroy was dissatisfied with Piedra for returning, and superseded him, when it devolved upon Don Francisco and Antonio Viedma (the officers next in command of those sent out from Spain) to carry into execution the intentions of their Government. These brothers were long employed upon various parts of the coast of Patagonia, and collected much valuable information respecting that terra incognita.

In April, 1779, Don Francisco sailed from San Joseph's, to form a settlement on the River Negro, in favour of which he was fortunate enough to propitiate the Viceroy, who supplied him with men and stores, and all things necessary for the purpose.

Don Antonio was left in charge at San Joseph's; but, the scurvy breaking out amongst the people to a great extent, they became so dissatisfied that he was under the necessity in the course of the summer of returning with the greater part of them to Monte Video. He was not, however, permitted to be long idle; and in the January following (1780) was again despatched to carry out the original plan, and to survey the whole of the southern part of the coast of Patagonia.

In furtherance of these orders, he examined the several ports of St. Helena, San Gregorio, the northern shores of the great Bay of San George, Port Desire, and San Julian's: which occupied him till the end of May, when, the cold weather setting in, he hutted his people for the winter at Port Desire, and despatched one of his vessels to Buenos Ayres with an account of his proceedings.

Of all the places he had visited, San Julian's appeared to offer the best, if not the only suitable site for any permanent establishment. Everywhere else, the coast presented the aspect of sandy, steril dunes, intermixed with stones and gravel, fit only, to all appearance, for the occupation of the wild guanacoes and ostriches, which wandered over them in quest of the scanty coarse grass which constituted their only herbage. No wood was to be seen bigger than a small species of thorny shrub, fit only for the purposes of fuel; and, as to water, it was every where scarce, and the little to be found was generally brackish and bad. The ports, too, were most of them difficult and dangerous of access, affording little or no security for vessels above the size of a brig.