Chap. VI.

FRANCE .

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fascines well bound were laid in, and the coffers of the grillage filled carefully with ma-sonry.

The celebrated breakwater , commenced by Louis Alexander dc Cessart, in the year 1783,was the most extraordinary work at this port; it was necessary to obtain a sufficientlyextensive harbour for the anchorage of the French fleet after the destruction of Dunkerque,there being no other refuge on the coasts.

Die difficulties were great, both in forming and defending it, some portions being carriedup to the height of 80 feet, as a rampart against the impetuosity of the waves or the attackof an enemy. To weaken the power of the sea, Cessart suggested the use of large truncatedwooden cones, base to base, loaded with stone, and placed in a line at half a league from theshore: they were prepared on land, floated to their destined position, filled with stone, andsunk ; after which, all above the level of low water was to be built up with good masonry,faced with granite, and laid in mortar composed of puzzolana. When all that belonged tothe construction was complete, the intervals between the tops of the cones was either to beclosed by iron chains suspended from eacli other, or guarded by a floating boat or pontoon,and it was supposed that such a construction would present a barrier to the power of theocean, and aftord at all times protection to 100 sail of the line. Batteries were afterwardsto be erected, which should rake the entrance at each end, and annoy an enemy approachingthe harbour.

Numerous projects and experiments were tried by the engineer, in the port of Havre,upon the effects of floating a truncated cone of 150 feet diameter at bottom, 60 feet at top,and 70 feet in height. It was calculated that ninety such cones placed contiguous to eachother would form a perfect breakwater. All the experiments upon the model having

Fig. 237.

succeeded, the government, after making it a subject of grave discussion, and examiningmany competent engineers and nautical men, ordered the works to be commenced. Cessartbeing instructed to revise and make various deviations from his original plan, constructedon a platform previously laid down on the shore a truncated cone, the lower diameterof which was 150 feet: around this were set up ninety timbers, at a distance of about

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