Studies of nature (Volume 1).

  • Saint-Pierre, Bernardin de, 1737-1814. Etudes de la nature. English
Date:
1808
Catalogue details

Licence: Public Domain Mark

Credit: Studies of nature (Volume 1). Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    liading itself straitened on passing from a wider to a narrower space, it forms' on the coast two counter-cui-rents, or vortices, wliich proceed in contrary di- rections. The one of these counter-cui-rents runs to the East, along the coast of Guinea, up to the fourth degree South, according to the testimony ofi?a»n. pier. The other takes it's departure from Cape St. Augustin, proceeds to the South-West, along the coasts of Brasil, up to Maire's-Strait inclu- sively. This effect is the result from a law in Hydraulics, the operation of which is generally knomi: it is this, that as often as a cun'ent passes from a wider channel into a narrower, it forms on the sides two counter-cui-rents. The truth of this may be ascertained by observing the current of a brook, or the passage of the water of a river under the arches near the abutment of a bridge, &c. Accordingly the current bears to the East, along the coasts of Guinea, and to tlic South-West, along tlie coasts of Brasil, during the Sum- mer of the South Pole. But in the middle of the Atlantic Ocean, and beyond the strait of the two Continents, it pushes on to the North in full force, and advances to the very northern extremities of Europe and of America, bring- ing us twice every day along our coasts the tides of the South, which are the half-tlaily effusions of the two sides of the South Pole. The other branch which issues from tlie South Pole, takes a direction to the westward of Cape Horn, ruslics into the Soutli Sea, produces in the Indian Ocean the Eastern monsoon, wliich takes place in India during our Winter ; and having made the tour of the Globe by the West, comes to the East, to unite Itself by the Cape of Good Hope to the general Cui-rent which enters into the Atlantic Ocean. It is possible partly to trace on the Chart this gene- ral Current of the South Pole, with it's two principal branches, it's couuter- cuiTents and it's tides, by the arrows which indicate it's direct, oblique, and retrograde movements. Six months after, that is in our Summer, commencing toward the end of March, when the Sun at the Line begins to forsake the South Pole, and pro- ceeds to warm the North, the effusions of the South Pole are stayed ; those of our Pole begin to flow, and the Currents of the Ocean change in all Lati- tudes. The general Current of the Seas then takes it's departure from our Fole, and divides, like that of the South, into tv.'o branches. The first of these branches derives it's sources from Waigat's, Hudson's bay, &c. which then flow in certain straits with the rapidity of a sluice, and produce toward ihe North tides which come from tlie North, from tlic East, and from the West, to the great astonishment of Linschoten, Ellis, and other Navigators, who had been accustomed to see them come from the Soutli along the coasts of Europe. This Current, formed by the fusion of most of the ices of the North of America, cf Europe, and of Asia, which at that season present a circumfer- t;nce of almost six thousand leagues, descends through the Atlantic Ocean, passes tlie Une, and finding itself confined at the same Strait of Guinea and J]rasil, it forms on it's sides two lateral counter-currents, which set in north- ward, as those formed six montlis before by tlic Current of tlie Soutli Pole set in southward. These counter-currents produce on tlic coasts of Europe, the tidc.^. which always appear to come directly from the South, though tlicv attually come at that season from tlie North.