Page:Popular Science Monthly Volume 48.djvu/470

430 The Ball Nozzle.—Mr. Arthur Kitson, in an address on the ball nozzle, published in the Journal of the Franklin Institute, gives the following explanation of its apparent contradiction of natural laws: The problem connected with this invention may be put thus: Why does the ball adhere to the nozzle when there is behind it a force aggregating as high as hundreds of pounds pressure? The explanation usually given is that the atmospheric pressure holds the ball in its place and prevents it from falling or leaving the mouth of the nozzle. To this others answer that the pressure behind the ball far exceeds the atmospheric pressure; for instance, there is an exhibition given daily in New York with one of these nozzles where the water pressure equals a hundred pounds per square inch, and as the atmospheric pressure is only about fifteen pounds, it would at first sight seem that the excess of pressure on the under side of the ball was eighty-five pounds, and ought, therefore, to expel the ball. The error, however, in this argument arises from failure to distinguish between the pressure of the water when confined in the pipes and when issuing around the ball. It is very certain that if a hundred pounds pressure were acting directly upon the ball, it would be blown out of the nozzle, but it does not appear to me to act in this way. When the ball is confined to the mouth of the nozzle and pressed against it, it is undoubtedly subjected to the pressure of the water, but the moment it is raised slightly from the mouth, it is no longer subjected to this pressure, since the water is escaping all around it. In this respect it resembles the lid of a teakettle when the water is boiling. By plugging the spout, the lid will be raised by the steam pressure sufficiently to allow the steam to escape at the sides. The explanation that seems to me to be the correct one is as follows: The ball is acted upon by three forces: first, gravity; second, atmospheric pressure; and, third, the force of the issuing stream. At first, the atmospheric pressure is the same at all points, and hence gravity has free play; but as soon as the stream passes through the nozzle, the atmospheric pressure from the under side is counteracted by the momentum of the issuing water, and the ball rising to a point where the water can pass freely around the sides, without pressing materially upon the ball, we have the full pressure of the atmosphere on the under half-side of the ball resisting the force of gravity. The ball, therefore, simply serves as a deflector to divert the current of water or to spread it out, and the resistance of the atmosphere against the ball suffices not only to perform this operation but also to sustain its weight.

It is possible that the density of the air may also be somewhat increased under the ball by the action of the spray. With a heavy pressure, the ball is farther removed from the nozzle than with a light pressure. The same holds good respecting a heavy ball and a light ball.

Native Sulphur in Michigan.—Beds of native sulphur are described by W. H. Scherzar in the American Journal of Science as having been discovered during the past year in the upper Helderberg limestone of Monroe County, Mich. They lie from sixteen to eighteen feet below the surface, between a compact, dolomitic limestone and a calcareous sand rock. They consist of a yellowish-brown, impure limestone, containing fossils, and giving here and there a strong, oily odor, which, wherever exposed to view, appears to be cavernous in structure, having pockets of from a fraction of an inch up to three feet in size. These pockets contain scalenohedrons of calcite or tabular crystals of celestite, or both together; while the sulphur generally occurs in bright, lustrous masses toward the center of the cavity, intermatted frequently with the lime minerals. Fragments as large as one's fist are readily removed. Some of the smaller cavities contain nothing but pure sulphur. Nearly one hundred barrels of pure sulphur have been obtained from about an acre of this bed.

Antirabic SernmSerum [sic].—In the light of some of the recent experimental work of Tizzoni and Centanni, published in the Lancet, there seems little doubt that a great advance has been made in the treatment of rabies. Instead of manufacturing the antitoxic material in the body of the patient, by a process of vaccination as in the Pasteur method, Tizzoni and Centanni prepare this substance in an animal, from which it is conveyed to the individual to be treated, in the blood