Page:Popular Science Monthly Volume 45.djvu/738

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THE POPULAR SCIENCE MONTHLY.

Bay of Fundy, coast of Maine, Boston basin, and the central Carolinas; while the western belt crosses the Eastern Townships and follows the Blue Ridge through southern Pennsylvania, Maryland, Virginia, and North Carolina, to Georgia. Further and fuller Studies of the subject are desired by the author, who remarks that the identification of truly volcanic rocks in highly or partly crystalline terrains possesses far more than a petrographical significance, since, by fixing what was the surface at the time of their formation, they furnish a certain datum for tracing out the sequence of later geographic changes and geological development.

 

A "Copper Age."—An account of the discoveries made at Tel-el-Heyi, the site of the ancient city of Lachish, in Palestine, gave rise, in the British Association, to a discussion concerning a probable copper age. The very high mound contains the ruins of several towns, built each (except the lowest) on the ruined remains of its predecessor The uppermost was an Israelitish town, and was very probably the remains of the Lachish which was besieged and destroyed by Sennacherib in the time of Hezekiah. Throughout the mound, from the bottom to the top, were found flint and metallic implements. Among them was a thick chisel made of copper, which had been hardened by mixture with red oxide of copper, from which it received a red appearance. Toward the top of the mound were bronze arrowheads, which probably dated back to between 1400 and 1500 years b. c. In the ascent of the mound a change was observed from copper to bronze and from bronze to iron, which was very common in the Israelitish town. Lead was found in the form of a thick wire, very pure. A silver bangle contained ninety per cent of silver, considerable copper, and an appreciable quantity of gold. Sir John Evans spoke of the evidences of a copper age preceding a bronze age, seen in North America, Ireland, Hungary, and other countries. Dr. Hildebrand said that several implements of pure copper had been found in Sweden. Prof. Boyd Dawkins thought the evidence from North America showed that the copper age was practically a side of the neolithic age. Prof. A. H. Sayce spoke of the absence of words for tin in the Egyptian and Assyrian languages, although the metal was known in Egypt as far back as the eighteenth dynasty, and although there are words in both languages for gold, silver, iron, copper, bronze, lead, and possibly metallic antimony. The word for iron in Egyptian meant metal from heaven, and in Assyrian, heavenly metal. This would indicate that their iron was meteoric.

 

Feats of Diving Birds.—Naval architects are credited with saying that the highest speed in navigation could be obtained by submarine boats. The principle is illustrated in the diving birds, which are capable of shooting through the water with amazing velocity. While these birds live by catching fish in deep water far below the surface, they present many differences in outer appearance. In the collection at the London Zoölogical Gardens are black-footed penguins, guillemots, "darters," a puffin, and a cormorant. The penguin can not fly in the air, can not walk, but hops as if its feet were tied together; and can not swim; and can only with any grace fly under water. When the keeper of their quarters appears to feed the birds, they each behave in their characteristic way. The fish thrown into the water, the penguins instantly plunge beneath, when an astonishing change takes place, thus described by a writer in the Spectator: "The slow, ungainly bird is transformed into a swift and beautiful creature, beaded with globules of quicksilver, where the air clings to the close feathers, and flying through the clear and waveless depths with arrowy speed and powers of turning far greater than in any known form of aërial flight. The rapid and steady strokes of the wings are exactly similar to those of the air birds, while the feet float straight out, level with its body, unused for propulsion, or even as rudders, and as little needed in its progress as those of a wild duck when on the wing. The twists and turns necessary to follow the active little fish are made wholly by the strokes of one wing and the cessation of movement in the other; and the fish are chased, caught, and swallowed without the slightest relaxation of speed, in a submarine flight which is quite as rapid as that of most birds which take their prey in midair." The head and shoulders may be