Encouraged by this special advantage, the Americans constructed for the California and China trades, vessels of still greater dimensions, and of a still finer description, in which, for a time, they practically monopolised not merely the trade between New York and San Francisco, but also that between China and Great Britain. Attributing the depression from which they were suffering to the repeal of the Navigation Laws, as every branch of trade was then greatly depressed, our Shipowners naturally viewed, with great alarm, the rapid strides made by American shipping. Nor were their fears allayed by a reference to the Board of Trade returns; wherein it appeared that, while the increase of British shipping had, in the year previously to the repeal been 393,955 tons, there had been a decrease in the year after the repeal of 180,576 tons; while, concurrently with the falling off of British shipping, it was also shown that foreign vessels, entering inwards from foreign ports, had increased from 75,278 tons to 364,587 tons. Our position appeared, therefore, critical; and, had it not been for the resources we held within ourselves, and the indomitable energy of our people, foreign shipping might then have gained an ascendency which might not afterwards have been easily overcome. American shipping, above that of all other nations, had, hitherto, been moving onward with such rapid strides that though, in 1815, at the close of the war, the tonnage of the United States was not more than one-half that of Great Britain, it had risen by 1850 to 3,535,454 tons (including river and lake steamers), against 4,232,960 tons of British shipping, and bade fair, with the special advantages they now possessed, to surpass it in amount ere many years had elapsed. Under such circumstances, unusual efforts were necessary to maintain our position as the first of maritime nations.[132] We had, however, one advantage which our great American competitors did not possess. We had iron in abundance; and, about this period, we were specially directing our attention to the construction of iron ships to be propelled by the screw. Various of these vessels, to which I shall hereafter fully refer, were launched about the year 1850, and placed in competition with the American liners, which had long, all but monopolised the trade between the United States and Europe. Even if we could not build wooden ships, as was then feared, at as low a cost as the Americans, we had the advantage in labour, in the cost of equipment, and in being able to produce a superior class of vessels suited for the China and other distant trades, from our English oak.[133] [Sidenote: Jardine and Co. build vessels to compete with the Americans.] [Sidenote: Aberdeen “clippers.”]