710 



THE POPULAR SCIENCE MONTHLY. 



elements from the others. When our sun 

 filled the orbit of Neptune, it probably ap- 

 peared to the inhabitants of other worlds 

 as a variable star, with a period of three 

 hundred and forty year3. 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 neb- 

 ulae 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 ob- 

 served even in these bodies. The origin of 

 new stars that remain may be explained by 

 supposing that the concussion was less vio- 

 lent 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, re- 

 cently 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 po- 

 sition among the tribes. The change in be- 

 lief seems rather to have been a loss of be- 

 lief, for it is remarked respecting the exer- 



cise of their religion that they never utter a 

 prayer, and have no regular form of public 

 worship, but simply invoke, the name of Mo- 

 hammed. 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. " Notwithstand- 

 ing this," they continued, " even if we ac- 

 cepted their practices, they would not cease 

 calling us converted." 



The Eucalyptus in California. Mr. Rob- 

 ert E. C. Stearns, Ph. D., communicated to 

 the American Forestry Association, at its 

 recent meeting, a number of facts respect- ' 

 ing the cultivation of the eucalyptus in Cal- 

 ifornia, 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 gen- 

 eral 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 in- 

 judicious planting, remediable by remand- 

 ing the eucalyptus to its proper place, and 

 by interspersing it with native and decidu- 

 ous trees, for the sake of variety in the 

 appearance. The globulus species of euca- 

 lyptus 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 with- 

 in the influence of the coast climate, where 

 the saline quality of the coast atmosphere 

 neutralizes the occasionally too low tem- 

 perature of the winter months, often fails 

 in the interior. 28 Fahr. is about the tem- 

 perature 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 



