Page:Popular Science Monthly Volume 2.djvu/527

Rh judge, say they are a little smaller than in the English towns."

The Uses of Asbestos.—The mineral formation called asbestos—which term denotes rather a peculiar form assumed by sundry minerals than any particular species—is coming to be used very largely in practical mechanics and manufactures. The name asbestos, signifying indestructible, was given by the ancients to various amphibolic and augitic minerals, which occur in long, hair-like crystals, placed side by side, forming a fibrous mass. These crystals may easily be taken apart, and, as they are very elastic and pliant, have been used to manufacture a sort of cloth. The Romans used sometimes to envelop the bodies of their dead in a wrapping of this fabric, thus keeping their ashes separate from the ashes of the funeral-pile, for fire does not consume asbestos. We even read of napkins and articles of dress being made of this material—when soiled they were cleansed by being subjected to the action of fire. In ancient times the wicks of the ever-burning lamps in temples and shrines were often of asbestos, and at the present time the Greenlanders make a like use of it. A few years ago a Mr. Audesluys, proprietor of a large asbestos-deposit in the vicinity of Baltimore, commenced the manufacture of a paper containing about 30 per cent, of asbestos. Characters written on such paper, in common ink, are still legible after it has been subjected to the action of fire, and it is likely that advantage will be taken of this property of asbestos to manufacture a paper for important records. The great objection to all the asbestos paper so far made is its want of toughness, its friability. The Journal of the Society of Arts makes mention of an asbestos paper covering for roofs, but, as this mineral is not proof against moisture as it is against fire, experience alone could determine its value for that purpose. But, perhaps, the most important service yet rendered by asbestos is the furnishing us with a fire-resisting packing for piston and pump rods, the necks of revolving retorts, etc. Asbestos packing was used for the piston of a locomotive on the Caledonian Railway from July 27 to November 18, 1871, and was then as good as when it was first put in; while the best common packing would have lasted not above two months. It is better to make rings of asbestos, and put them on the piston, than to wind it round. There are very extensive deposits of this important mineral within the limits of the United States, that found on the eastern slope of the Green Mountains and of the Adirondacks being of the best quality for fineness and tensile strength. The fibre of New York and Vermont asbestos varies in length from two to forty inches, and resembles unbleached flax, when found near the surface; but when taken at a greater depth it is pure white, and very strong and flexible. It is found also in considerable quantities in the Tyrol, in Hungary, Corsica, and Wales.

British Scientific Expedition.—The enlightened liberality of the British Government in fitting out the steam-corvette Challenger, 2,306 tons, for a scientific voyage around the globe, receives the heartiest commendation from the English press, and from the whole world of science. The commander of the corvette, Captain Nares, R.N., is a distinguished seaman and explorer, and the second in command, Commander J. P. Maclear, R.N., is scarcely less eminent. We have space only for the names of a few of the scientific men who go out on this cruise. The director is Prof. Wyville Thompson, and he has under him J. J. Wild, of Zurich; J. Y. Buchanan, of Edinburgh, chemist; H. N. Mosely, naturalist; Dr. Von W. Suhm, do.; John Murray, Edinburgh University, do. The vessel has been thoroughly repaired and fitted for her work, with auxiliary screw, two engines of 400 horse-power each, boats, 40 dredges, etc. She carries an abundance of traps, harpoons, scientific apparatus, etc. The route of the vessel will probably be, first, to Gibraltar and the Bay of Biscay; thence to Madeira, St. Thomas, the Bahamas, Bermuda, and the Azores. From the Azores she will sail for Bahia, touching at Fernando Noronha. Thence she crosses to the Cape of Good Hope, from which point her course is southward to the Crozetts and Marion Islands and Kerguelen's Land. Thence her direction will still be southward, as far as the ice will permit, and then the vessel will steer for Sydney, New Zealand, the