Page:Popular Science Monthly Volume 52.djvu/737

Rh him in the valley of Acoma in central New Mexico. The Katzimo, or enchanted mesa, is an isolated mass of rock rising from the center of the plain to a height of four hundred and thirty feet. Native tradition has it that this was once the home of their ancestors, but during a great convulsion of Nature, at a time when most of the inhabitants were at work in their fields below, an immense rocky mass became freed from the friable wall of the cliff, destroying the only trail to the summit and leaving a few old women to perish on the inaccessible height. This tradition has been strengthened by the finding of numerous fragments of pottery of very ancient type in the talus beneath the wall where it is said the path originally existed, and also by traces of hand and foot holes for some distance up the side of the cliff. Professor Hodge, by the aid of an extension ladder and several hundred feet of rope, after two hours' hard work, succeeded in reaching the summit of the mesa. The first recorded ascent was that of Professor Libby, of Princeton, in July, 1897. Several ancient potsherds and a curious sort of monument were the only archaeological finds. Professor Hodge, however, drew a map of the surface and accurately determined its altitude.

The Age of Trees.—The following information is taken from a recent circular of the United States Department of Agriculture: In all the timber trees of the temperate portion of our country the wood of the stem is laid on in sheets, which on any cross-section appear as so many concentric rings. Generally these rings are sufficiently well defined to be readily counted, and since only one is formed during each growing season they furnish a very convenient record of the age of that portion of the tree. In the cross-section of a pine, fir, or cedar these rings appear as alternate narrow bands of lighter and darker color, the dark line, or "summer wood," occupying the outer portion of any one ring, and being sharply contrasted against the lightest part of the inner lighter, or "spring wood." These rings are conspicuous through rows of pores, each row occupying the inner or spring wood part of a ring and being separated from the row of pores of the next ring by wood practically devoid of large pores. In the "diffuse porous" woods, like birch, poplar, tulip, etc., the rings are generally less conspicuous, being defined by a mere line, often scarcely perceptible in the fresh wood, and due to the fact that the outermost cells of the summer wood are always small, flattened in form, and have thick walls, while the adjoining innermost cells of the spring wood of the neighboring ring are much larger, not flattened, and always have thin walls. The growth of these rings is very even and regular, especially in young and thrifty timber, where the conditions for tree life are favorable. Where the conditions are not good the ring formation varies in a number of ways, and is a not at all reliable source for obtaining the age of the tree. A cross-section from one to two feet, above the ground should have added to the number of rings found from five to seven years, as the seedling would probably have required that period to reach a height of two feet.

The Pitch Lake of Trinidad.—Some romances and exaggerations of which the pitch lake of Trinidad has been the subject are corrected by Mr. Albert Cronise, of Rochester, N. Y. Its area, height, and distance from the sea have been overestimated, and a volcanic action has been ascribed to it which does not really exist. It is one mile from the landing place, is one hundred and thirty-eight feet above sea level, is irregular, approximately round, and has an area of one hundred and nine acres. Its surface is a few feet higher than the ground immediately around it, having been lifted up by the pressure from below. The material of the lake is solid to a depth of several feet, except in a few spots in the center, where it remains soft, but usually not hot or boiling. But as the condition of the softest part varies, it may be that it boils sometimes. The surface of the lake is marked by fissures two or three feet wide, and slightly depressed spots, all of which are filled with rain water. In going about, one has to pick his way among the larger puddles, and jump many of the smaller connecting streams. Each of the hundreds of irregular portions separated by this network of fissures is said to have a slow revolving motion upon a horizontal axis at right angles to a line from the center of the lake, the surface moving