Abstract
American Journal of Science, February.—Researches in acoustics, by A. M. Mayer. This paper, dealing with the variation of the modulus of elasticity with change of temperature, and the acoustic properties of aluminium, was read before the British Association at the Oxford meeting.—On the improbability of finding isolated shoals in the open sea by sailing over the geographical positions in which they are charted, by G. W. Littlehales. Suppose that A discovers, in the open ocean, a shoal r miles in radius, and determines the geographical position of its centre subject to extreme errors of m miles in longitude and n miles in latitude; and that B, who is able to establish his geographical position within the same limits of extreme error as A, attempts to find the shoal again by proceeding to the geographical position assigned to it by A, what is the probability that he will find it? The author works out this probability mathematically, and finds a general formula for it. If r = 1 mile, and m and n = 10 miles, B would stand one chance in 6173 of coming within two miles of the shoal. This shows that the reported non-existence of a charted shoal must be accepted with great care.—The counter-twisted curl aneroid, by Carl Barus. A curl aneroid, less than a metre long, provided with a mirror for registry, will indicate variations of atmospheric pressure of a thousandth of a millimetre of mercury, provided the mounting is sufficiently free from tremor, and the temperature is kept constant to a few thousandths of a degree during the interval of observation. The conditions are made much less severe if the coiled tube, after being twisted, is kept untwisted by a spiral spring. Effects of viscosity and rigidity may be thus compensated.
Article PDF
Rights and permissions
About this article
Cite this article
Scientific Serials. Nature 53, 452–453 (1896). https://doi.org/10.1038/053452a0
Issue Date:
DOI: https://doi.org/10.1038/053452a0