In 1830 published the Mechanics’ magazine an article dealing with the necessity of making a breakwater in Portlands Roads. The author compared this plan with the naval works of the French harbour and base Cherbourg and supplies useful information, including some history facts. Cherbourg was a threat for the British interests including the control over the British Channel.
P. 194: “The progress made by the French nation at Cherbourg in completing a capacious harbour and safe roadstead, as well as several docks for shipping, of the largest dimensions, has for more than a century been an object of attention and consideration to the British government. As early as 1697, Louis XIV formed a design of enlarging and fortifying that place and harbour, which was 'done at intervals. In 175S, it was considered by our government as of no trivial consequence, and likely to become the cause of much danger and alarm, that an expedition sailed under the command of the late Earl Howe, which destroyed nearly the whole of the works. Immediately after the preliminaries of peace were signed, in 1783, the views of the French were again directed to Cherbourg; and by renewed exertions, they have at length established it as a naval arsenal of the first consequence. Some part of the present works were commenced by Louis XVI; the greater proportion, however, were executed and nearly brought to perfection by Buonaparte. The undertaking is of a magnitude very difficult to be comprehended by those who are not conversant with works of this nature, and therefore an attempt to convey some idea of it is highly necessary. The grand breakwater at Cherbourg was commenced under the direction of Doumourier in ten fathoms water, and allowing about 30 feet for the rise or flow of the tide, it .required a structure of 90 feet perpendicular to attain the level of high-water mark ; five times the height is calculated as the extent of its base. The breadth at the base will therefore he 450 feet, and at least 4134 tons of stone may be calculated for every yard in length, or to erect it at low-water mark, not less than 1946 tons must have been required for every yard. A part of the breakwater is above high-water, but some parts of it are barely up to low-water mark. This immense edifice extends three miles from east to west, fronting the harbour, and at a moderate calculation must have required the enormous quantity of 10,974,280 tons of stone, for the most part quarried for the express purpose from a hill of granite "situated behind Cherbourg, about one mile distant from the shore. In addition to this work, fortifications on a very extensive scale have been carried on, and a naval arsenal completed with numerous docks, sufficiently capacious to admit ships of the largest class; these works have been all formed out of the solid rock near Fort Hornmet, a mile distant from the old works. The national advantages to the French, in time of war, of the important situation of Cherbourg, are very considerable, by affording adequate protection to their naval and commercial shipping, and enabling them considerably to annoy the English.”
p. 196: “The idea of a breakwater in so central a point of the British Channel originated with himself in 1704; since which period to the close of his life, he strictly watched the progressive advancement of Cherbourg tip to its present importance, and constantly availed himself of every possible means of representing the matter where it was likely to obtain the attention which the subject so highly deserves, as well as in maturing his plans to carry it into effect in Portland Roads, and thereby to afford an efficient counteraction to the opposite port of Cherbourg.”
p. 197: “Before the breakwater was erected at Cherbourg, by which immense structure that port has become so formidable, England had greatly the advantage of France, because the intervention of the national harbours of Portsmouth and Plymouth between Brest and Toulon, obliged France to lit out the whole of a fleet at one or the other of those ports; and as no French national harbour then intervened between Portsmouth and Plymouth, much valuable time was saved in fitting out a part of the British fleet in each of those harbours. From the great importance which Cherbourg has attained, France is now placed, in this respect, in the same point of view in which England has hitherto been. In a report which M. de Vauban made to the French government, he gave it as his opinion that the roadstead of Cherbourg possessed the means alike of protection, of attack, and of defence; that it was capable of exerting an important influence also in war, and on the commercial relations with the northern powers ; that it was the spot of all others on which the head-quarter of the French should be established on the coast of the Channel ; that it was a central advance post with regard to England ; and that, moreover, it might be made a port for the safe retreat of a squadron crippled by storms, or beaten by an enemy, as well as for the reception of a victorious fleet with prizes. The fortifications for the protection of the anchorage in the roadstead, and the naval arsenal, are Querqueville, 30 guns; Fort du Hornet, 65 guns; Fort Gallet, 80 guns; Fort Royal on the Isle Pelée, SO guns. Fort Royal and Fort Hornet have circular faces towards the sea, with each two tiers of guns, and turrets above them ; the principal channel from the road to the sea is at the western end of the breakwater, and a fleet may push out to the westward in southerly winds, which lock up the English ports in the Channel. In addition to the breakwater, two immense basins, building-slips, and the docks connected with them, have been completed. The basins are for the most part excavated out of granite rock, one is 30 and the other 60 feet deep ; the ships are launched into, and docked out of the smaller one, which will contain about 16 sail of the line; the larger basin, 1000 feet in length by 770 in width, is for the fleet when ready for sea, in which 94 sail of the line can be moored with the greatest ease, by means of anchors inserted in the granite, and when required, can be at sea in a fu\v hours. The two basins communicate with each other, and with the harbour: a basin for merchant-ships was also completed in 1829. A narrow canal between the walls of Fort Hornet and the wall of the wet-dock leads to a most convenient space for mast-ponds and mast-houses. The covers over the slips and docks are on a grand and magnificent scale; they are erected on granite piers, with the roofs constructed on a most excellent principle, and executed in a very superior style; they are regularly slated, each roof having a number of rows of lights, each row containing 27 windows. The building of large ships at Cherbourg has been proceeded with in a very rapid manner; no less than 3 three-deckers were launched at the arsenal during 1817; and two other three-deckers, 2 ships of 100 guns on two decks, several frigates, and large steam-boats, were on the stocks in the same year.”
Source
The Mechanic’s magazine, museum, register, journal, and gazette, vol. 13, no. 355, Saturday 29 May 1830.
