FRAGMENTS OF SCIENCE. 



717 



him in the valley of Acoma in central New 

 Mexico. The Katzimo, or enchanted mesa, is 

 an isolated mass of rock rising from the cen- 

 ter 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 find- 

 ing 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 ex- 

 tension 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 infor- 

 mation is taken from a recent circular of the 

 United States Department of Agriculture : 

 In all the timber trees of the temperate por- 

 tion of our country the wood of the stem is 

 laid on in sheets, which on any cross-section 

 appear as so many concentric rings. Gen- 

 erally 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 con- 

 spicuous 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 in- 

 nermost cells of the spring wood of the 

 neighboring ring are much larger, not flat- 

 tened, and always have thin walls. The 

 growth of these rings is very even and regu- 

 lar, especially in young and thrifty timber, 

 where the conditions for tree life are favor- 

 able. Where the conditions are not good 

 the ring formation varies in a number of 

 ways, and is a not at all reliable source for ob- 

 taining 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 seed- 

 ling would probably have required that pe- 

 riod to reach a height of two feet. 



The Pitch Lake of Trinidad. — Some ro- 

 mances 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 dis- 

 tance 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, ex- 

 cept 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 va- 

 ries, it may be that it boils sometimes. The 

 surface of the lake is marked by fissures 

 two or three feet wide, and slightly de- 

 pressed 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 hori- 

 zontal axis at right angles to a line from the 

 center of the lake, the surface moving 



