Page:Popular Science Monthly Volume 17.djvu/147

 China and Japan in the same course as the storms and tempests of the Atlantic which reach Europe; 2. That such storms are independent of the prevailing monsoon, and reciprocally, neither interfering with the other. Thus, says M. Faye, in regions opposed to ours in the northern hemisphere, the storms which we call cyclones or typhoons follow identically the same course, whatever may be the distribution of water and land, whether there are currents of warm water like the Gulf Stream, chains of mountains or not, on their way, whatever may be the direction of the lower winds prevailing in the country. The origin of these gyratory phenomena is, then, in the upper region of the atmosphere, whence, away above all the superficial accidents of the globe, they descend to the ground through the lower strata.

Wild Silks.—That our resources for the production of silk are capable of great enlargement is shown by the fact that heretofore only a few of the numerous insects which form silk and only a small number of the plants on which they feed have been utilized, leaving the greater number of insects and plants still unemployed. The known silk-spinners belong to the two families Bombycidæ and Saturniidæ, of the Lepidoptera. All of the Saturniidæ are silk-spinners, but not all of the Bombycidæ. Of the Saturniidæ, the British Museum catalogue contains the names of two hundred and ninety-four species, and one hundred more species have been added since the catalogue was published. Mr. Thomas Wardle, in a lecture on the wild silks of India, before the Society of Arts, gave a list of fifty-seven silkworms indigenous to India, of which six mulberry-feeding sorts are domesticated, and the others are wild. Besides the mulberry-feeding worms, of which there are also nine wild species, the cocoons of fourteen wild species are utilized. Of these, the principal species are the Attacus ricini, the Attacus cynthia, or Eria-worm, the Antheræa Assama, or Muga-worm, and the Antheræa paphia, or Tusser-worm. The Attacus ricini is a native of Assam, and feeds on the castor-oil plant and several other plants of the country. The cocoons can not be reeled, but the fiber is exceedingly well adapted for spinning, can be dyed and print ed easily and satisfactorily, and forms a cloth of "incredible durability, the life of one person being seldom sufficient to wear out a garment made of it, so that the same piece descends from mother to daughter." Attacus cynthia feeds on the ailantus, and has been successfully domesticated in France and England, where "ailanticulture" has a recognized place in industrial economy. Its silk is not adapted for reeling, but spins well, and there is no doubt, says Mr. Wardle, "that a great future remains for this silk, now that spinning-machinery has been so perfected." The Attacus Atlas is almost omnivorous, yields a "decidedly good" silk, and has been recommended for introduction into France. The Antheræa Assama yields the Muga silk, which forms one of the chief exports of Assam. Five thousand acres are planted in Assam and some Tipperah villages with food for the worm, and are capable of yielding 123,000 pounds of the fiber. Mr. Wardle reports of the silk that it bleaches well, and takes the dye freely, better than Tusser. The Antheræa paphia, from which the Tusser silk is derived, is the most widely distributed as well as the most important of the wild-silk producers of India, and has been utilized for many centuries. It feeds on a variety of plants, among them the castor-oil plant, and begins to spin its cocoons in six weeks from the time it is hatched. The silk is woven and used in the provinces of India in mixed fabrics of cotton woof and Tusser weft, but seems also to be used pure in many cloths. The fiber of this silk is flat, thereby showing a strong difference from that of the mulberry silk, which is round, and to this is ascribed its glassy look. So far from this property being a drawback, the luster seems to be enhanced by it after the fiber has become modified and its flatness has been diffused in the loom. The chief obstacle to the general introduction of this silk is the difficulty with which it is made to take colors. A process has been invented to overcome this by applying oxygen to the natural fawn-colored coloring matter of the fiber, but it is too expensive for general use. Mr. Wardle has found a partial solution of the difficulty in a more thorough cleansing of the native product and better reeling, and has made the silk submit to the dye and to the printing process in a tolerably