Page:Popular Science Monthly Volume 21.djvu/726

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THE POPULAR SCIENCE MONTHLY.

elements from the others. When our sun filled the orbit of Neptune, it probably appeared to the inhabitants of other worlds as a variable star, with a period of three hundred and forty years. The appearance of change is confined to the youth of a star; for when it has become so dense that the variations bear only a minute ratio to the absolute brightness of the body, they cease to be noticed. The gradual and seemingly permanent disappearance of stars that have suddenly shone out is accounted for by supposing their periods of change to be immensely long. As hundreds of years must have elapsed after our sun first shone out before the gaseous particles began to move back toward the center, so, if the concussion is vastly more violent than that which produced the sun, thousands of years must pass before a concentration can begin. The origin of the apparently constant nebulae may be thus accounted for, and their irregularities of shape may have arisen from different accidents of the concussion; but changes of magnitude have been observed even in these bodies. The origin of new stars that remain may be explained by supposing that the concussion was less violent—strong enough to produce a great brightness, but not strong enough to cause immense expansion. Professor Ritter claims that spectroscopical observations of the "newer stars" are in harmony with his theory.

 

A newly discovered Jewish Tribe.—Mr. Henry Samuel Morais has published a short account of the Daggatouns, a tribe of Jewish origin in the Desert of Sahara, recently brought into notice in the narrative of the Rabbi Mordecai Aby Serour, of Akka, Morocco. The rabbi's account is incomplete, but we may learn from it that the people mentioned, who are scattered among the orthodox Tuaricks in the desert, "have skins perfectly white, are very handsome, much handsomer than the finest-looking Jews of Africa," and that not one of them is black. They are distinguished by the Tuaricks as Jews that have changed their belief, and seem to occupy a low social position among the tribes. The change in belief seems rather to have been a loss of belief, for it is remarked respecting the exercise of their religion that they never utter a prayer, and have no regular form of public worship, but simply invoke, the name of Mohammed. To questions on the subject they emphatically answered that they did not know the Koran, and that, having-descended from the Jews, and not resembling in any manner the other tribes, they could not have exactly the same religion. "Notwithstanding this," they continued, "even if we accepted their practices, they would not cease calling us converted."

 

The Eucalyptus in California.—Mr. Robert E. C. Stearns, Ph. D., communicated to the American Forestry Association, at its recent meeting, a number of facts respecting the cultivation of the eucalyptus in California, and the probable value of the tree. About six million eucalyptus-trees have been planted in the State during the last ten years, and several million trees of other kinds. A large proportion of the number have been planted in the streets and yards of cities, and for ornament in country estates, till, in the absence of deciduous trees, "the vistas afforded by the streets are somber and monotonous through general sameness of form and tone of color. The eucalyptus is a greedy monopolist, and, when planted in a small yard, takes all there is of it, killing out the shrubs. These objectionable facts, however, are not faults of the tree per se, but are only effects of injudicious planting, remediable by remanding the eucalyptus to its proper place, and by interspersing it with native and deciduous trees, for the sake of variety in the appearance. The globulus species of eucalyptus is the one most planted, but it is probably of less value for most purposes, aside from the fact of its rapid growth, than its harder-wooded congeners. This species, also, "which seems generally to thrive within the influence of the coast climate, where the saline quality of the coast atmosphere neutralizes the occasionally too low temperature of the winter months, often fails in the interior. 28° Fahr. is about the temperature limit as to cold." Touching the value of the eucalyptus for lumber, based upon the product of California-grown trees, "but little can be said. The time has not arrived to determine that question. The