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Page:Popular Science Monthly Volume 35.djvu/149

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Geological Progress.—In reviewing the progress made by geological science during the last twenty-four years, Prof. W. Boyd Dawkins mentions the advantages which it has drawn from microscopic analysis of the rocks, in the study of metamorphism, and of the crushing and shearing forces that were brought to bear on the cooling crust of the earth; and from deep-sea explorations, revealing the structure and deposits of the ocean abysses. From a comparison of these deposits with the stratified rocks, we may conclude that the latter are marginal, and deposited in depths not greater than one thousand fathoms, or at the shore end of the globigerina ooze, and most of them at a less depth—and that consequently there is no proof in the geological record of the ocean depths having ever been in any other than their present places. In North America, the geological survey of the Western States has brought to light an almost unbroken series of animal remains, ranging from the Eocene down to the Pleistocene age. In these we find the missing links in the pedigree of the horse, and sufficient evidence of transitional forms to enable Prof. Flower to restore to its place in classification the order Ungulata of Cuvier. These may be expected to occupy the energies of American geologists for many years, and to yield further proof of the truth of the doctrine of evolution.


Yucatan Hammocks.—With a couple of straight poles, a shuttle, a thin slab of zapoli-wood, and a pile of heniquen-leaves at hand, says Consul Thompson, of Merida, the Yucatecan is ready to accept contracts for hammocks by the piece, dozen, or hundred. The poles are placed a distance apart, according to the required length of the hammock. The thin slab of hard wood is fashioned into a stripper, by the aid of which the fiber of the thick heniquen-leaf is denuded of its envelope, and a wisp of rasped fiber is obtained. This having been bleached, the fibers are separated into a certain number, and these are rolled into a strand. Two or more of these strands are then taken out, and by a similar dexterous manipulation converted into a han or cord, from which the hammock is made. The cord is riven rapidly around the two upright poles, and the shuttle, worked by the women, seems to move and seek the right mesh, says Consul Thompson, with a volition of its own—and in a very short space of time the hammock is made and laid with its kind, to await the coming of the contractor. Almost the entire exportation of hammocks from Yucatan is absorbed by the United States. All the districts of the State produce hammocks, but that of Tixcoco more than all the other districts combined. Chemax hammocks are noted for their fineness, and do not have to seek a market abroad.


What is Fire-proof?—The idea that theatrical appurtenances of wood and cloth can be made efficiently fire-proof by soaking them with certain chemical solutions is, in the opinion of Mr. Walter Emden, a serious error. Theoretically, the soaking works beautifully, and in practice for a time secures immunity against the spread of fire. "But for how long? Of the majority of those preservative solutions, it is a question if anything is left at the end of a certain time. They evaporate or sublimate or pass off into the atmosphere. No one can say with any degree of certainty for what length of time a beam or a cloth will be fire-proof as the result of soaking in any non-inflammable solution. Now, miscalculations in respect to this may lead to the most terrible catastrophes." A further point of the greatest moment is that gas-flames raise the temperature of wood and canvas in their vicinity to 140° F., and dry them to tinder. Obviously, actual contact with a caked flame must, under such circumstances, produce results altogether different from those of the experiments usually made with preservative solutions. It is the materials themselves which are used in the construction that must be proof against fire. The aim should be, not to make some combustible material incombustible, but to use only fire-proof materials.


Bread of Water-Lily Seeds.—The seeds of various species of water-lilies form the food of thousands of people in Asia and some parts of America. The most important species for this purpose are those belonging to the genus Trapa, which are known in India as Singhara, in China as Ling, and generally as water-chestnut. The fruit of the Trapa bicornis, which grows in the lakes of