Bore, the rapid rushing of the tide inland against the current of a river. This phenomenon takes place when a narrow river falls into a gradually widening estuary subject to high tides. At spring tides the great volume of water which enters the wide mouth of the estuary is compressed as it advances till it is several feet higher than the mouth of the river, up which it therefore rushes like a torrent. In England the bore is observed in the Severn and Trent rivers and in Sol way frith. There is a remarkable bore in the Hoogly branch of the Ganges, where the current goes 70 m. in 4 hours; also at the mouth of the Brahmapootra, where no boat ventures to navigate at spring tide, and at the mouth of the Indus. The rise of the tide in the bay of Fundy resembles a bore, and this phenomenon occurs in some of the smaller rivers on the coast of Brazil, as well as in the Amazon on a large scale.

Boreas. (From a bass relief on the Temple of the Winds, Athens).

Boreas. (From a bass relief on the Temple of the Winds, Athens).