Notwithstanding the obvious utility of wet-docks, and the vast trade of the British Metropolis, there was no establishment of this sort on the Thames till nearly a century after a wet-dock had been constructed at Liverpool. The inconvenience arising from the crowded state of the river at those periods when the fleets of merchantmen were accustomed to arrive, the very insufficient accommodation afforded by the legal quays and sufferance-wharfs; the necessity under which many ships were placed of unloading in the river by means of fighters, and the insecurity and loss of property thence arising, had been felt and complained of as an intolerable grievance. But so powerful was the opposition to any change, made by the private wharfingers and others interested in the support of the existing order of things, that it was not till 1793 that a plan was projected for making wet-docks for the Port of London, yet the activity and enterprise of the merchants and shipowners of the metropolis have, since that date, amply compensated for their lost time, and the docks of London are now models of superiority in that peculiar department of civil engineering. Though not included in the engraving, the recent improvements which have been effected in its vicinity by the public spirit of the Corporation of London, demand a passing tribute of admiration. The New Coal Exchange is an edifice worthy of the purpose for which it was designed--the mart for the sale of one of Great Britain's most valuable products; and Billingsgate is now a market fitting for a city containing two millions of inhabitants. [Illustration: THE TOWER OF LONDON.] THE TOWER OF LONDON. This celebrated fortress is situated on the east side of the City, a short distance from London-bridge, near the banks of the river Thames. It at first consisted of no more than what is at present called the White Tower, traditionally reported, without any authority, to have been built by Julius Cæsar, though there is the strongest evidence of its being marked out and a part of it first erected by William the Conqueror, in the year 1076, doubtless with a view to secure to himself and followers a safe retreat, in case the English should ever have recourse to arms to recover their ancient possessions and lost liberties.