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THE POPULAR SCIENCE MONTHLY. 



rectly worked out, we have to draw the con- 

 clusion that not all the projected great tun- 

 nels 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 unen- 

 durable unless the air is perfectly dry. A 

 shorter tunnel, projected by Clo, Varetz, and 

 Jacquemin, will be more feasible. A pro- 

 jected tunnel under Mont Blanc will prob- 

 ably have to be made in an extreme tem- 

 perature of 51 C, and this will be impos- 

 sible. It follows from these observations 

 that while we may generally be able to over- 

 come the difficulties imposed in tunnel-mak- 

 ing by length and geological structure, we 

 are not always competent to contend against 

 those imposed by temperature. 



Interesting Finds in Pompeii. In enter- 

 ing Pompeii, says a recent visitor, writing in 

 " Chambers's Journal," " we descend a slop- 

 ing 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 arc the perfect 

 remains of beautiful temples with their mar- 

 ble 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 cal- 

 drons 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 en- 

 trance-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 evi- 

 dently 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 col- 

 lection of surgical instruments greatly in- 

 terested a celebrated physician who was 

 one of our party, and who expressed un- 

 bounded surprise at the very slight differ- 

 ence 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, 6oft 

 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 skele- 

 tons." 



Life on Coral Islands. The Chagos Ar- 

 chipelago, the southernmost island of which, 

 Diego Garcia, has been made a coaling-sta- 

 tion 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 cir- 

 cumference " a lake with a shore and noth- 

 ing 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 cov- 

 ered with trees, which are chiefly cocoanut- 

 trees, with various kinds of tree-ferns, and a 

 few flowering shrubs. The archipelago con- 

 sists 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 dan- 

 gerous atoll, that nowhere rises above high- 

 water mark, and near it some thirty islands, 



