rectly worked out, we have to draw the conclusion that not all the projected great tunnels are practicable. Dr. Stapff calculates that the Simplon Tunnel, as projected by Favre and Clo, will develop temperatures of 46·9° C. in the stone, 45·85° in the air, and 54·3° in the water, which will be unendurable unless the air is perfectly dry. A shorter tunnel, projected by Clo, Varetz, and Jacquemin, will be more feasible. A projected tunnel under Mont Blanc will probably have to be made in an extreme temperature of 51° C, and this will be impossible. It follows from these observations that while we may generally be able to overcome the difficulties imposed in tunnel-making by length and geological structure, we are not always competent to contend against those imposed by temperature.
Interesting Finds in Pompeii.—In entering Pompeii, says a recent visitor, writing in "Chambers's Journal," "we descend a sloping path to the silent city, which stands between two enormous embankments of ashes, like a very deep railway-cutting, and enter by the great gateway, with arches and pillars in perfect preservation. Through a small arch at the side, intended for foot passengers, we pass into the deserted streets; from the high, narrow footway we see the tracks of wheels on the paved street below; and the great stepping-stones are still there, as in the days of old. Everywhere stand the remains of sculptured fountains—at the street corners, in every house, in every square. A number of converging streets lead into the Forum. Here are the perfect remains of beautiful temples with their marble columns and sculptured altars, on which the inscriptions may still be read. On some are delicate carvings representing sacrifice, in high-relief, with every detail clear and sharp as when first chiseled. We go through the street of the soap-makers and visit the large soap-works, where the huge iron caldrons are still left. Another street is full of wine-shops, with the large red jars still inserted in the marble counters. Then we pass the city bake-houses, where ovens were found full of charred bread, which is now in the Naples Museum, the baker's name stamped upon each loaf. Close by are the splendid public baths, with every appliance for hot, cold, and vapor baths, the pipes and cisterns still remaining. Near the entrance-gate is a small museum containing the skeletons found in the city—a mother and daughter clasped in each other's arms; a sentinel found at his post; a man evidently knocked down by the cloud of ashes; and several others. Some of them have been injured in the process of excavation. When a skeleton is found, hot plaster-of Paris is immediately poured into it, so that while preserving the skeleton intact, it gives also, by filling up the impression or mold of the body that had lain there, the form and features of the living man. A large collection of surgical instruments greatly interested a celebrated physician who was one of our party, and who expressed unbounded surprise at the very slight difference between these relics of the infancy of medical science and the instruments in use at the present day. Some large cases of dentists' tools caught our eye also. . . . A great number of paint-boxes are displayed, which still contain the same bright, soft colors that we see on the walls of Pompeii; and case after case of jewels, some found in the house, others evidently dropped in hurried flight from the burning city, or fallen from the necks and arms of the skeletons."
Life on Coral Islands.—The Chagos Archipelago, the southernmost island of which, Diego Garcia, has been made a coaling-station for steamers, may be taken as typical examples of coral islands. Diego Garcia is nearly in the longitude of Bombay, and 7 south of the equator. It is an island of the "atoll" type, fully thirty miles in circumference—"a lake with a shore and nothing else." The shore, in some places a few feet, in others a few yards, but never so much as a quarter of a mile wide, is entirely covered with trees, which are chiefly cocoanut trees, with various kinds of tree-ferns, and a few flowering shrubs. The archipelago consists of several groups, among which are the Six Islands, which lie in a ring, and are linked together by coral reefs that approach the surface of the sea, but do not rise above it. South of these is the Pitt Bank, a very dangerous atoll, that nowhere rises above high-water mark, and near it some thirty islands,
