" Floating " bridges are roadways carried on pontoons moored in a stream.
Other forms show no indication of ever having been attached, while some that had been moored by means of a peduncle during the early portion of their existence have become detached at a more advanced stage of life, the opening becoming gradually cicatrized, as is so often seen in Leptaena rhomboidalis, Orthisina anomala, &c. Lastly, some species adhere to submarine objects by a larger or smaller portion of their ventral valve, as is the case with many forms of Crania, Thecidium, Davidsonia, &c. Some Cranias are always attached by the whole surface of their lower or ventral valve, which models itself and fills up all the projections or depressions existing on either the rock, shell or coral to which it adhered.
For smallpox the Board maintains hospital ships moored in the Thames at Dartford, and a land establishment at the same place.
It owes most of its interest to the peace signed here in July 1807, the preliminaries of which were settled by the emperors Alexander and Napoleon on a raft moored in the Memel.
Though the harbour is deep and extensive, and possessed of excellent anchorage, large vessels have to be moored at a considerable distance from the shore.