a two days journey, which goes by the village of Pequeni, and is full of the greatest difficulties.

In every age and climate, of two neighbouring seas, the one has been considered as more elevated than the other. Traces of this vulgar opinion are to be found among the ancients. Strabo relates, that in his time the gulf of Corinth near Lechaeum was believed to be above the level of the sea of Cenchreae. He is of opinion that it would be very dangerous to cut the isthmus of the Peloponesus in the place where the Corinthians, by means of particular machines, had established a portage. In America, the South Sea is generally supposed to be higher at the isthmus of Panama than the Atlantic ocean. After a struggle of several days against the current of the Rio Chagre, we naturally believe the ascent to be greater than the descent from the hills near Cruces to Panama. Nothing, in fact, can be more treacherous than the estimates which we are apt to form of the difference of level on a long and easy descent. I could hardly believe my own eyes at Peru, when I found, by means of a barometrical measurement, that the city of Lima was 91 toises† higher than the port of Callao. An earthquake must cover entirely the rock of the isle San Lorenzo with water before the

* Strabo, lib. i. ed. Siebenkees, v. I. p. 146. Livius, lib. 42. cap. 16.

† 582 feet. Trans.

ocean can reach the capital of Peru.

The idea of a difference of level between the Atlantic and South Sea has been combated by Don George Juan, who found the height of the column of mercury the same at the mouth of the Chagre and at Panama.

The imperfection of the meteorological instruments then in use, and the want of every sort of thermometrical correction of the calculation of heights, might also give rise to doubts. These doubts have acquired additional force since the French engineers, in the expedition to Egypt, found the Red Sea six toises higher than the Mediterranean. Till a geometrical survey be executed in the isthmus itself, we can only have recourse to barometrical measurements. Those made by me at the mouth of the Rio Sinu in the Atlantic Sea, and on the coast of the South Sea in Peru, prove, with every allowance for temperature, that if there is a difference of level between the two seas, it cannot exceed six or seven metres t.

When we consider the effect of the current of rotation, which carries the waters from east to west, and accumulates them towards the coast of Costa Ricca and Veragua, we are tempted to ad

38 feet. Trans.

† 19 or 22 feet. Trans.

I call current of rotation the general motion from east to west, observed in the part of the ocean comprised in the torrid

zone.

mit, contrary to the received opinion, that the Atlantic is a little higher than the South Sea. Trivial causes of a local nature, such as the configuration of the coast, currents and winds (as in the Straits of Babelmandel), may trouble the equilibrium which ought necessarily to exist between all the parts of the ocean. As the tides rise at Portobello to a third part of a metre *, and at Panama to four or five metres t, the levels of the two neighbouring seas ought to vary with the different establishments of the ports. But these trivial inequalities, far from obstructing hydrau lical operations, would even be favourable for sluices.

We cannot doubt that if the isthmus of Panama were once burst by some similar catastrophe to that which opened the columns of Hercules ‡, the current of rotation in place of ascending towards the gulf of Mexico, and issuing through the canal of Bahama, would follow the same pa rallel from the coast of Paria to the Philippine islands. The effect of this opening, or new strait, would extend much beyond the banks of Newfoundland, and would either occasion the disappearance or diminish the celerity of the Hotwater river, known by the name of Gulf-stream §,

* 13 inches. Trans.'

13 or 16 feet. Trans. Diodorus Siculus, lib. iv. p. 226. lib. xvii. p. 533. edit.

Rhodom.

§ The Gulf-stream, on which Franklin and afterwards

which leaving Florida on the north-east, flows in the 43° of latitude to the east, and especially the south-east towards the coast of Africa. Such would be the effects of an inundation analogous to that of which the memory has been preserved in the traditions of the Samothracians. But shall we dare to compare the pitiful works of man with. canals cut by nature herself, with straits like the Hellespont and the Dardanelles !

Strabo * appears inclined to believe that the sea will one day open the isthmus of Suez. No such catastrophe can be expected in the isthmus of Panama, unless enormous volcanic convulsions, very improbable in the actual state of repose of our planet, should occasion extraordinary revolutions. A tongue of land lengthened out from east to west in a direction almost parallel to that of the current of rotation escapes, as it were, the shock of the waves. The isthmus of Panama would be se riously threatened, if it extended from south to

Williams, have left us such valuable observations, carries rapidly the tropical waters to the northern latitudes. It is occasioned by the current of rotation which strikes against the coasts of Veragua and Honduras, and ascending towards the gulf of Mexico, between Cape Cutoche and Cape St. Antoine, issues through the canal of Bahama. It is owing to this mo tion that the vegetable productions of the Antilles are carried to Norway, Ireland, and the Canaries. See the second volume of my voyage to the tropics, chap. i.

* Strabo, ed. Siebenkees, T. I. p. 156.

north, and was situated between the port of Car thago and the mouth of the Rio San Juan, if the narrowest part of the new continent lay between the 10° and the 11° of latitude.

The navigation of the river Chagre is difficult, both on account of its sinuosities and the celerity of the current, frequently from one to two metres per second. These sinuosities however afford a counter current, by means of which the small vessels called bongos, and chatas, ascend the river, either with oars, poles, or towing. Were these sinuosities to be cut, and the old bed of the river to be dried up, this advantage would cease, and it would be infinitely difficult to arrive from the North Sea to Cruces.

From all the information which I could procure relating to this isthmus, while I remained at Car thagena and Guayaquil, it appears to me, that the expectation of a canal of seven metrest in depth, and from twenty-two to twenty-eight met est in breadth, which, like a pass or a strait, should go from sea to sea, and admit the vessels which sail from Europe to the East Indies, ought to be completely abandoned. The elevation of the ground would force the engineer to have recourse either to subterraneous galleries, or to the system

* From 3.28 to 6.56 feet. Trans.

+22 feet 1 inches. Trans.

From 72 feet 2 inches, to 91 feet 10 inches. Trans.