Charles Maire de la Condamine, the astronomer, was sent by the French government in 1735 to measure an arc of the meridian on the plain of Quito, and on his return in 1740 he addressed the French Academy of Sciences in behalf of a canal at Nicaragua, which he declared to be quite practicable. He was accompanied across the Isthmus by Don George Juan, and by Don Antonio de Ulloa, the distinguished Spanish scientist and statesman who was afterward governor of Louisiana in 1764; but competent as the expedition was, it appears to have made only most superficial examinations of the ground. During the latter half of the eighteenth century a few sporadic and futile essays were made to select a route. Augustin Cramer and Miguel del Corral surveyed the Tehuantepec route, and Ysasi, Muestro, and Alexandre the Nicaragua route, but their labours were fruitless. The illustrious Horatio Nelson led an expedition to Nicaragua in 1780, to seize the lakes and control the interoceanic route, but did little more than permanently impair his own health. The next year Manuel Galisteo surveyed the Nicaragua route and reported to the Spanish government that it would be impossible to construct a canal from the lakes to the Pacific. In 1788 a Spanish engineer officer, Manuel Milla, was sent by his government over the Caledonian Bay route, which Sharpe and Wafer had traversed long before, and which Paterson had surveyed. His report was even more favourable than Wafer's had been and must be regarded as grossly exaggerating the ease with which a canal could be constructed there. The native tribes were so troublesome, however, as to keep the Spanish government from making any further efforts in that region. Moreover, both war and science were preparing to open an entirely new era in the history of the Isthmus and of interoceanic trade.

WITH the opening years of the nineteenth century a new era in Isthmian exploration and in canal schemes was begun. Its foremost pioneer was the great scientific genius Alexander von Humboldt, who spent the years from 1799 to 1804 in Mexico (then still called New Spain), Central America, and the northwestern states of South America. His scientific researches were of incalculable value, but none of them surpassed in interest and suggestion his observations upon the feasibility and desirability of constructing an artificial waterway between the Atlantic and Pacific oceans. In his "Political Essay on New Spain" he described the Central American Isthmus, the "barrier against the waves of the Atlantic," as having been for many ages "the bulwark of the independence of China and Japan." Only by making a navigable channel across that Isthmus, he believed, could "any great changes be effected in the political state of Eastern Asia." Such an undertaking was "calculated to immortalise a government occupied with the true interests of humanity." Of the practicability of it he had no doubts. No fewer than nine routes were considered by him, for waterways between the two oceans. The first, beginning at the north, involved the Mississippi, Missouri, Peace, and Columbia rivers, with a passage over the "Stony" or Rocky Mountains, which latter, he was informed, were in some places as much as 3,520 feet high! The second was by way of the RioBravo, or Rio Grande del Norte, in Mexico, and the Rio Colorado, entering the Gulf of California. The third was at the Isthmus of Tehuantepec, Mexico, making use of the Coatzacoalcos River. The fourth was at Nicaragua, where

the great lakes appeared to him to offer special facilities for navigation, as did also the San Juan River. He appears

to have known, as he certainly should have known, that the San Juan River flows from the lakes to the Caribbean Sea, though strangely enough one of his maps of that region indicates it as flowing into the lakes, and a separate river, the Colorado, flowing into the Caribbean, with a mountain range between them.

The fifth route was that at Panama, from the City of Panama to Venta de Cruces, at the head of navigation on the Chagres River, near Obispo and Gamboa, on the present railroad and canal route. To this he devoted most attention of all. "That canal," he said, "would have to pass through a hilly tract, of the height of which we are completely ignorant. . . . It is very astonishing that in crossing the Isthmus neither La Condamine nor Don George Juan and Ulloa had the curiosity to observe their barometer, for the sake of informing us what is the height of the most elevated point on the route. . . . However, it appears beyond a doubt that we find the principal Cordillera, or, rather, a range of hills that may be regarded as a prolongation of the Andes of New Granada, between Cruces and Panama. It is from them that the two oceans are said to be discernible at the same time, which would only require an absolute height of 290 metres. However, Lionel Wafer complains that he could not enjoy this interesting spectacle. He assures us that the hills are separated by valleys which allow free course for the passage of the rivers. If this be true, we might believe in the possibility of a canal from Cruces to Panama, of which the navigation would be interrupted by only a very few locks." The 290 metres, or 951 feet, suggested by Humboldt, was really more than three times the actual height of the loftiest hill on the route ultimately selected for the Panama Canal.

After further consideration of the Panama route, Humboldt continued: "It appears to me that the expectation of a canal of seven metres in depth and from 22 to 28 metres in