Page:Popular Science Monthly Volume 40.djvu/297

Rh They now threaten to cover up the few existing fields on the Tigris. While extensive tracts in these regions have been lost to cultivation from the lack of water, another part is suffering from its superabundance, and the land is swamp at the normal level of the streams. Such is now what was once the most populous region of the earth.

Tests of Woods.—A system of tests of woods was described by Prof. Fernow at the meeting of the American Association, which have been undertaken at the Department of Agriculture for the determination of the relation of technical and physical qualities to each other and to conditions of growth. The method includes the selection of testmaterial from as many essentially different soil and climatic conditions as the species may occupy; the examination of the structure and physical condition of the material down to the minutest detail; the usual testing with special care; and the compilation and comparative discussion of the results of the tests in connection with the physical examination and the known conditions of growth. Besides more reliable data than have been hitherto obtained of the qualities of our principal timbers, the investigation promises to furnish us with a knowledge of the conditions under which desirable qualities can be produced by the forest-grower.

Phosphorus in Plants and Animals.—In a paper presented to the American Association meeting in 1890, Mr. Walter Maxwell showed that a vegetable organism, during the initial stages of growth and under the action of the ferments operating in germination, possesses the power of taking the phosphorus present in seeds or in soils as mineral phosphates, separating the phosphorus from the inorganic combination, and causing it to appear in the young plantlet in an organic form as a lecithine. In a second part of his paper, which was read at the association meeting of 1891, the author showed that the lecithine bodies present in the animal kingdom revert to the mineral form under the action of the ferments present in the animal organism. The phosphorus contained in a hen's egg, with which the investigations were conducted—both in the forms of mineral phosphates and of organic phosphorus compounds as lecithines—was first determined. Next, eggs were incubated, and the products of incubation were studied. It was found that the phosphorus contained in the natural egg as a lecithine reappeared in the incubation product as calcium phosphate, forming the bone of the chicken. It thus appears from the investigations that the lecithine bodies are a medium through which phosphorus conducts its circulation between the mineral, vegetable, and animal kingdoms—passing from the mineral, through the vegetable, into the animal kingdom, where it reappears as a mineral compound.

Carpet-weaving in Persia.—Few ancient carpets are to be found in Persia now, the stock having been gathered up by European travelers, merchants, and curio hunters. It may seem almost incredible to many people that among the ancient carpets so many are still in good condition and comparatively little worn. The secret of this is, according to M. G. de Vries, that not only has great care been bestowed on the weaving of the carpets and on the quality of wool used, but because of the custom prevailing in the houses of Eastern people. While we enter our own and other people's rooms with the same boots with which we walk through the muddy streets, a Persian never enters any room without leaving his boots or shoes at the door. The most important present manufacture of carpets is carried on at Sultanabad. The weaving is done exclusively by women. The only share the men take in the work is, that to them the merchants give out the designs, the colors, and the money required for the weaving. The loom is an inexpensive and simple structure, consisting of four wooden poles, which generally occupy the whole length of the weaving-room. When weaving is going on regularly, three or four women work at a carpet of fairly large size, the weaver's wife being, as a rule, the principal weaver, and at the same time superintending the work of her daughters or hired women. The rule is, that, at each end of the board on which the women arc seated, there shall be one female overseer. For carpets of very large size, in the weaving of which seven or eight women are employed, there is also an overseer in the middle. At the age of seven years girls begin to assist in the