force, many workers and many thinkers have helped to build up the nineteenth-century school of plenum—one ether for light, heat, electricity, magnetism; and the German and English volumes containing Hertz's electrical papers, given to the world in the last decade of the century, will be a splendid monument of the consummation now realized. The Royal Society's Transactions and Proceedings of the last forty years contain, in the communications of Gassiot, Andrews and Tait, Cromwell, Yarley, De la Rue and Müller, Spottiswoode, Moulton, Plücker, Crookes, Grove, Robinson, Schuster, J. J. Thomson, and Fleming, almost a complete history of the new province of electrical science, which has grown up largely in virtue of the great modern improvements in practical methods for exhausting air from glass vessels, by which we now have "vacuum tubes" and bulbs containing less than 1190000 of the air which would be left in them by all that could be done in the way of exhausting (supposed to be down to one millimetre of mercury) by the best air-pump of fifty years ago. A large part of the fresh discoveries in this province have been made by the authors of these communications, and their references to the discoveries of other workers very nearly complete the history of all that has been done in the way of investigating the transmission of electricity through highly rarefied air and gases since the time of Faraday.
Paleontological Riches of Texas.—In his report to the State Geological Survey on the Invertebrate Paleontology of the Texas Cretaceous, F. W. Cragin characterized the State as a mine of paleontological research, particularly with respect to the extensive and as y(*t little known faunae of its Comanche series. The work of the recently deceased Dr. Roemer, the little illustrated but mainly accurate paleontological work of Dr. Shumard, the work of Conrad upon the collections made by the Mexican Boundary Survey, not to mention numerous lesser contributions by Marcou, White, Hill, Giebel Schlueter, and others, all taken together, have only tapped this great mine of knowledge. And this, as regards invertebrate forms alone; for the vertebrates of the Texas Cretaceous, and particularly those vertebrate faunas which are of the greatest importance as factors of the stratigraphic and taxonomic problems of the lower rocks of the Comanche series, are almost wholly unknown. Of the remains of Cretaceous invertebrate organisms a great wealth of material has been accumulated by the survey, including types of many new forms of exact biological and stratigraphical significance.
Manganese in Alabama.—A report on the geological structure of Murphree's Valley, Alabama, made to the State Geologist by Assistant A. M. Gibson, shows that besides limestone and hematite and limonite iron ores, the estimates of the value of which have been confirmed in the working, it contains manganese ores and beds of fine clays. Half a dozen or more spots are described, all in the same region, where deposits of manganese ores, chiefly pyrolusite, of good quality, have been seen. The discoveries of these deposits have been in the main accidental, and they cover only a very small part of the ground where ores are presumed to exist. It is therefore probable that the larger proportion of the beds still remain undiscovered. The clays comprise brick clays and halloysite or porcelain clay—a similar bed to which has been worked with satisfactory results in De Kalb County—along with which are a honestone grit, sandstones, and honestones suitable for building, and a fireproof conglomerate. Besides two lines of exposure of iron ores and one of carboniferous limestone, this valley is favored with "ample coal accessible on both sides at its very edge."
Arago's Work.—In his address at the unveiling of a statue of Arago, in Paris, June 11th, M. Tisserand said that "Arago introduced physics into astronomy, and gave it a permanent place. Before him, astronomers concerned themselves chiefly with the movements of the stars and the members of our planetary system, seeking to explain them in their minutest details by the law of gravitation. Arago studied the nature of the heavenly bodies, and the character of the phenomena continually exhibited by them. The polariscope showed him that the glaring surface of the sun is gaseous, and gave him important information as to the light of comets. Another application of physical methods furnished him with a pre-
