Page:Popular Science Monthly Volume 41.djvu/444

430 places and tracts of land within the Commonwealth. The property thus acquired, which can not, with its appurtenances, exceed two million dollars in aggregate value, is exempt from taxation, unless it is held longer than two years without being opened to the public. While the corporation enjoys these privileges, it is forbidden to own any capital stock or to make any division of property or income among its members, or any dividends. Mr. George F. Hoar has been chosen President of the Board. The trustees received last year several recommendations or offers of property as coming within the category of the purposes for which they are acting, and have considered the expediency of purchasing them; and Mr. J. B. Harrison, their agent, has made an inspection of the sea-coast towns of the State, with a view to the provision of public access to the beach and the establishment of seashore parks. The establishment of the board will enable the admirers of the scenery or history of any spot in the State to make that spot a reservation and to provide for its perpetual care, and will enable the proprietors of pleasure resorts and the people of communities which make money from the attractiveness of fine scenery to insure the perpetuation of such attractions and of their profits. Similar provisions should be made in all the States.

Characteristics of Star Spectra.—The general conclusion derived from the study of the spectra of the stars, says Prof. E. Pickering, in his account of the Henry Draper Memorial, is the marked similarity in constitution of different stars. A large part of them—the stars of the "first type"—have a spectrum which at first sight seems to be continuous, except that it is traversed by broad dark bands, due to hydrogen. Closer inspection shows that the K-line is also present as a fine dark line. If the dispersion is large and the definition good, many more dark lines are visible. These lines may be divided into two classes: First, those which predominate in many stars in the milky way, especially in the constellation of Orion; and, second, those present in the solar spectrum. Nearly all the brighter stars may be arranged in a sequence, beginning with those in Orion, in which the auxiliary lines are nearly as intense as those due to hydrogen. Other stars may be found in which these lines successively become fainter and fainter, till they have nearly disappeared. The more marked solar lines then appear, become stronger and stronger, and the hydrogen lines fainter, till they gradually merge into a spectrum apparently identical with that of the sun. Continuing the sequence, the spectra pass gradually into those of the third type. Certain bands become more marked, and the spectra of the third type may be divided into four classes, in the fourth of which the hydrogen lines are bright instead of dark. This spectrum appears to be characteristic of the variable stars of long period when near their maximum. It has led to the detection of several new variable stars, and has been confirmed in many of the known variables. Slight peculiarities are noticed in the spectra of many stars, but these deviations are not sufficient to affect the general law. Stars of the fourth type, whose spectra appear to be identical with the spectrum of carbon, are not included in this classification. Other stars, whose spectra consist mainly of bright lines, like those of the planetary nebula?, may be included with them in a fifth class.

The Reason of the Slave Trade.—A Moslem view of the slave trade is presented in the Saturday Review—not to excuse the traffic, but to show why it is carried on. The slaves are mostly children, "black, uncomely, and unpromising." They are not sought for the harem, in the conventional sense of that word. "The truth is, that certain conditions of domestic life among civilized Moslems exact a supply of slaves without regard to beauty or even to physical strength. The interruption of that supply has caused as much dismay and confusion as a law to forbid the employment of unmarried girls for household service might effect in England. It would be found at once that there were not matrons or widows enough to do the work, that few of them would undertake it, and fewer still were competent. Such a law would be evaded at every peril. No class of women in a Moslem community has the tradition of domestic service, as it may be called. Very commonly a free girl was taken into the household of some matron as a child, and there brought up; but she