1. The Commissioners appointed to examine and report upon the state of our Coast Defences, have recommended the construction of additional Fortifications at various points, which, it is computed, will involve an outlay of several millions sterling. The defences of the dockyards and arsenals are, very properly, to be strengthened so as to enable them to resist the attacks of steam-ships armed with rifled cannon; and every assailable part of the coast is to be protected against an invading force. The defence of London forms no part of the scheme; that most important topic having been omitted in the Defence Commission. The reason for such an extraordinary omission need not here be discussed: suffice it to say that, while the extremities are guarded, the heart of the country is left exposed.[1] Our first line of defence, the Channel Fleet, is provided to prevent the sudden descent of a hostile force upon our shores. Our second line, consisting of forts on various parts of the coast, will, no doubt, be strengthened by powerful batteries. A third and innermost line of defences, for the protection of the Capital, the seat of Government, the centre of the wealth and commerce of the nation, is wanting. To show how this deficiency may be supplied, speedily, and economically, and at the same time so effectually as to make London impregnable and successful invasion hopeless, is the purpose of this article. 2. If ever an invasion of England be attempted, the point to be aimed at by the invader will be the capture of London; and for the very simple reason that _it_ alone would repay the cost and risks of an attack. If Portsmouth dockyard were destroyed, Devonport would remain; if both were lost, there would be Chatham; give all three to an enemy, and we have Pembroke; let him take all four, and England might still build ships in the Clyde and the Severn and the Mersey by private enterprise: better, perchance, than in royal dockyards, the gun-boat failures notwithstanding. An enemy would not be likely to place himself permanently on Portland Bill, or any other part of England; and certainly no burning of dockyards, or any other similar contingency, would be likely to induce England to capitulate and make terms. What might happen if a conqueror were to get possession of the Bank of England, and appoint a General of Division Governor _pro tem._, who would make the bank parlour his head-quarters, and bid his soldiers mount guard over the bullion-vaults, it is difficult to say. With London in a state of siege, a Provost-Marshal installed at the Mansion House, a park of artillery on Tower Hill, the Royal Exchange and Guildhall converted into military posts, and a foreign soldiery quartered upon the inhabitants, there would be no “Quotations” of Consols on the Stock Exchange, nor any of the usual telegrams or leading articles in the newspapers. The Government would be powerless for anything but “making terms” with the invading