Page:Popular Science Monthly Volume 30.djvu/738

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THE POPULAR SCIENCE MONTHLY.

jade, or jadeite—which varies in color from almost milk-white, with a slight shade of green, to a beautiful emerald-green—has not been found in place in America. So far as is known, all the varieties come from Asia. That it was rare, and regarded of great value among these Central American people, is shown by the fact that they wrought it into finished ornaments with such care, and that to make those ornaments they cut up eelts already of value as useful manufactured articles, instead of using rough stones. The question is then in place, whether it is not reasonable to believe that the stone was brought from Asia in the form of implements by the early migrants to this country; and that, as the supply was not kept up, and most likely even its source became unknown, the pieces among the people were cut and recut, and preserved as sacred relics of the past, to be, one after the other, finally buried with their owners?

Oscillations of Italian Soil.—M. Quesnault read a paper, at the recent meeting of the French Association, on his researches into the oscillations of the ground and the movements of the sea. He had already laid some of his observations on the subject before the previous meeting of the Association, and they had been received with favor. He ascribed the changes of level which the ground undergoes to two very different causes: those of one character, sudden and transitory, were traceable to volcanic phenomena; others were attributable to sublunary and atmospheric influences. Those more general movements, which manifest themselves slowly and regularly either in depression or elevation, could be explained only on the supposition of an astronomical revolution of long duration not yet ascertained, that modifies the center of gravity of our planet and the motion of the waters that cover it. Professor Issel, of the University of Genoa, presented some valuable facts on the modifications of level, both slow and rapid, which the soil of Italy has undergone through a long series of years. Some of these facts, the result of slow and secular movements, are well worthy of attention. Thus, the Venetian estuary and Istria have been subject during historical times to a sensible depression which amounts at Venice to three or four centimetres in a century. The same movement is very evidently manifested on the coasts of Dalmatia, Albania, and Greece, and probably extends across the Mediterranean to Barbary and Egypt. Malta is or has been in the track of the depression. In Sicily, less evidently, Professor Issel takes notice of an elevation, which may have amounted to between four and six metres, since 400 B.C. A similar movement seems to have taken place on the Calabrian littoral opposite to Sicily; but this fact of elevation being common to nearly the whole of the Mediterranean basin, we are led to connect it with some astronomical phenomenon rather than with a change in the level of the sea. Professor Issel also remarks that, while we observe signs of recent depression at certain points of the Italian coasts, other evidences are plainly exhibited of a previous elevation (quaternary), which attained, in Liguria, a height of twenty metres.

Barometric Wells.—Some wells in Meyrin, Canton of Geneva, Switzerland, have barometric properties. They have been closed at the top, except for a small airhole, and through this the wind blows in or out, according to the conditions of atmospheric pressure, sometimes with force enough to make a sound like that of a steamwhistle. If a hat or any light article be put over the hole when the barometer is falling, it will be blown up at once; but if the outer pressure is rising, the draught will bring leaves and other light objects toward the well. The people of the village understand the action of the wells, and make it their weather gauge. The origin of the phenomenon is easily explained. It is dependent upon the differences that may be produced at any time between the pressure of the air within the wells and that of the outer atmosphere.

Asafœtida.—The gum asafœtida is derived from an umbelliferous plant (Ferula asafœtida) which grows in Persia and Afghanistan and other parts of Central Asia. Some information regarding the preparation of the gum is given in Dr. Jaworsky's account of his travels in those regions, which was published during 1885. The author