Since the preceding pages were written, Captain Washington, secretary to the Royal Geographical Society, has favoured me with the longitudes of the places adverted to, as ascertained by Captain Forster, and in February 1837 by Captain Belcher, R.N. Porto Bello is in 79° 30' West long.; Chagre, 79° 55'; and Panama in 79° 29' 20". This gives the distance from Chagre to Panama 33 geographical miles. Porto Bello is in lat. 9° 32' North. From thence to the Pacific, a little to the east of Panama, is 30 miles. From Chagre to the mouth of the Caymito will be 30 miles. Ulloa's calculations of longitudes would thus appear to be wrong.]
This survey commenced from the eastern suburb of Panama, at high-water mark, and ran along the old road to Porto Bello, unto the point where it crossed the Rio Chagre,--a distance of 1828 chains, 22-3/4 miles. The highest land passed over was the ridge Maria Henrique, 12-3/4 miles from Panama, and 10 from the Chagre. Its height is 633.32 feet. The point where the road approaches the river, is 169.840 feet above the level of high-water mark at Panama; and the bed of the river from whence the survey commenced downwards, is 152.55 feet. Descending the river 1545 chains, 19-1/2 miles, Mr. Lloyd came to the village of Cruces, after a descent of 114.60 feet; thus making Cruces to be 37.96 feet above high-water mark at Panama. From Cruces to Gorgona 410 chains, 5-1/4 miles, the fall is 16.13 feet; and thence to a small gravel bank, named "_Playa los Ingenieros_" distant from Cruces 1302 chains, 16-3/4 miles, the fall is 21.82 feet, precisely level with the high-water mark at Panama. At 2682 chains, 33-1/2 miles below Cruces, Mr. Lloyd first observed the effects of the tide from the Atlantic, the level of the river at this point being 13.65 feet below the level of high-water mark on the Pacific. At 507 chains, 12 miles, further down, reached La Bruja, where the water became brackish; the level of the surface of the river being 13.55 feet below the high-water mark at Panama. From La Bruja there was no perceptible descent to the Atlantic. The whole distance gone over in levelling from sea to sea, was 82 miles.
The tide at the mouth of the Chagre rises only one foot, or 1.16 feet; but at Panama the spring-tide in the Pacific rises in a mean level (p. 093) to the height of 21.22 feet, though high winds and currents occasionally raise them to the height of 27.44 feet. At low water the sea sinks proportionally at Panama below the level of the Atlantic: the reason for this difference is obvious. The current towards the Gulf of Mexico, and which afterwards forms the famous gulf stream, carries off rapidly the waters in the Atlantic; while, on the contrary, the current which flows northward along the western coast of South America, and the tide which flows into the bay of Panama, from the south-west from the Pacific, heaps, as it were for a moment, the waters into the bay and on the shores of Panama, and occasions the tides alluded to, and differing so greatly from those which are seen in the Atlantic at the short distance on the opposite coast.