REPORT OF BOARD OF CONSULTING ENGINEERS, PANAMA CANAL. PHYSICAL CHARACTERISTICS OF THE PANAMA ROUTE. The combination of a very narrow isthmus with low summit is found at Panama. The route practicable for a canal there is not half as long as the Suez Canal. The portion of this route that is higher than the highest cutting at Suez is about seven miles in extent. The drainage of the Isthmus throughout about three-fourths of its width is effected through the ChagresRiver and its tributaries to the Caribbean, and of the. remaining one-fourth through the Rio Grande to the Pacific. The proposed Pacific terminus is about 20 miles farther east than the Caribbean terminus, for at the Panama Isthmus the trend of the two coasts, there approximately parallel, is about east and west. The drainage to the Pacific is now effected through the Rio Grande, a small stream discharging into Panama Bay to the west of Sosa Hill and about two miles west of the city of Panama. The tidal oscillation in Limon Bay, the initial point of the canal route, is about two feet, while at Panama it is about 20 feet. The harbors are not naturally good, but they have been made to suffice for the limited traffic seeking this route. The geologic features of the Isthmus are very well described by two eminent French scientists, a translation of whose report on this subject, together with the deductions from the existing facts as affecting proposed engineering operations, and especially the stability of the banks of the channel and slopes, are very lucidly set forth in a paper which will be found in Appendix B, while climatic conditions are treated in the section of this report which is devoted to this important subject. As before stated, the drainage toward the Atlantic is naturally effected through the Chagres, the canal line by all plans being located in the immediate valley of that stream for about 21 miles. One of its tributaries, the Obispo, drains the extension of the canal line for about five miles toward the Culebra summit. The Chagres is a torrential stream, and drains a basin of an estimated total area of about 1,200 square miles, about half of which is above the point where the proposed canal line leaves the river. Its sources are in the San Blas Mountains to the northeast. The course of the Chagres is, in a general way, parallel to the Caribbean coast as far as the mouth of the Obispo, where it turns to the northward and follows a somewhat tortuous but on the whole fairly direct course to the Atlantic rim of its upper basin at Bohio, about 13 miles below the mouth of the Obispo. At Gatun, about 10 miles below Bohio, following the general course of the valley, the direct distance to the Atlantic at the head of Limon Bay is only three miles, but the river deviates to the westward, and after a further course of about seven miles, passing to the west of Limon Bay, discharges into the sea at the old. village of Chagres, about five miles west of Point Toro. Above Bohio the Chagres Valley is undulating or hilly,.the declivities becoming steeper toward the sources of the river, where the country is mountainous. 'At Alhajuela, about eight miles in a direct line above the mouth of the Obispo, the low-water surface of the river is about 95 feet above sea level, and at the mouth of the Obispo 45 feet; but at Bohio, 13 miles farther down, it is practically at sea level. From Bohio to the sea the surface of the ground for considerable areas in the vicinity of the river is but little above sea level. In this low region the Chagres receives several tributaries, of which the Gatun from the eastward and the Trinidad from the westward are of considerable size. There are several notable topographic features of the.Chagres Valley which have a very important bearing upon the canal problem. In the upper courses of the stream and its tributaries the bottom in the waterway is the original rock formation, and the channel is strewn with bowlders, pebbles, and sand which have been loosened by erosion. Borings have been made in this valley at several points from Alhajuela to Gatun, with a view of determining the character of the earth and depth to rock. It is found that at Aihajuela there is a depth of about 29 feet of gravel overlying the rock in midstream. The rock outcroppings in the bluff appears to be of a firm and homogeneous structure, of volcanic origin. At this point the hills on either side contract the valley in a marked degree. At Gamboa, which is just above the junction of the Obispo, the 15