The so-called Isthmus of Chiriqui, lying between Panama and Nicaragua, was explored by the late Lieut. St. Clair Morton, who was killed in the siege of Petersburg. Lieut. Morton crossed the Isthmus twice, and pronounced the route practicable for a railroad. As no notes of this survey are extant, curiosity in regard to this route must remain unsatisfied. Lieut. Jeffers, U. S. N., speaks favorably of the harbors. Mr. Evans, the geologist, discovered an inferior kind of coal. Another reconnoissance may develop some important information. COSTA RICA. A railroad has been projected from Port Limon, near the tenth parallel of latitude on the Atlantic, to Caldera, in the Gulf of Nicoya. Rising to an altitude of 5,100 feet the route passes through a salubrious climate, and over a productive soil. A macadamized road, 134 miles long, with five stone bridges, has been completed along this line. As a route for a ship canal the altitude of the summit appears to exclude it from further consideration. PANAMA. As the passenger route and highway of the trade between the Atlantic and Pacific States of America, the mention of this line arrests attention. Information in regard to it is full and accurate. Here, alone, in all Central America, a railroad unites the two oceans. Confining his remarks to the project of M. Garella, Admiral Davis pronounces his condemnation of the route. M. Garella’s route, starting from the Bay of Limon, on the Atlantic, following the valley of the Chagres, ascending with 17 locks to the summit, which it passes with a tunnel 17,500 feet in length, at an altitude of 135 feet above high water in the Pacific, and descending with 18 locks, terminates at the Bay of Vaca del Monte, on the Atlantic. The altitude of the ridge to be pierced is 459 feet. The commission of the “_Ponts et chaussés_” appointed to report upon Garella’s project, object to the expense of tunneling, and to the absence of evidence of the sufficiency of the mountain streams to feed the summit level. But a tunnel is not a necessary plan of piercing the Isthmus at this point, nor is a summit level 135 feet above high water an unavoidable necessity. The Panama railroad passes the divide without a tunnel, at an altitude of 280 feet above tide. The fact that a route possessing such advantages should be found so near the line of M. Garella, encourages the belief that a more critical examination of other prescribed routes may be rewarded with the same good fortune. The merits above mentioned justify a more attentive consideration. The advantages of the route may be enumerated as follows: