Page:Popular Science Monthly Volume 49.djvu/156

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144
THE POPULAR SCIENCE MONTHLY.

desired to measure, the pressure remaining constant and being that of the atmosphere. As the density of the gas diminishes, the interference fringes become displaced. By reducing the pressure of the gas in the second or cold tube, the fringes are brought back to their initial position; and this means that the density is then the same in both tubes. Now, the refraction of a gas is always exactly proportional to its density: the density of the gas in the cold tube is known from its pressure. Hence the density of the hot tube is also known, and from this its temperature is deduced. The method is thought to be well adapted for the measurement of high temperatures, such as those of furnaces,



NOTES.

Abundant testimony is cited by Mr. Walter Hough to the fact that the use of body armor was at one time general if not universal among the North American Indian tribes. The form was usually that of a sleeveless jacket, coat, or wide band, going around the trunk, suspended from the shoulders. At the period of its disuse, six types of armor were found on this continent and in contiguous regions — viz., rows of overlapping plates, perforated and lashed; wooden slats twined together; wooden rods twined together; bands of skin arranged in telescope fashion; coats of hardened hide; and cotton-padded armor.

Prof. Marshall Ward has found from his experimental work of the past few years that the appearance of colonies of the same bacterium, when grown under different conditions, are often very unlike. Distinctions of species, therefore, should not be based only upon the appearance of the colony, but should be drawn after study of all the conditions of the medium.

Dr. Treub, director of the botanical gardens of Buitenzorg, Java, gave an account, in the British Association, of the formation of hydrocyanic acid in the pangia tree (Pangium edule), and especially of the relation of the acid to the formation of nitrogenous material in plants. He considers that it is, in pangium at least, the first detectable nitrogenous material, and suggested, as an inference, that it is possibly very widely distributed in the vegetable kingdom as a transitory substance which becomes rapidly transformed into more complex substances.

The agitation of a proposition to rename one of the boulevards of Paris after Pasteur has developed the fact that besides there being already a rue Pasteur, twenty-one streets in Paris are named after chemists. Among the men thus remembered are Chevreul, Gay-Lussac, Lavoisier, Raspail, Davy, and Berzelius. Seven botanists are thus honored, one alchemist — Nicholas Flannel, of the fourteenth century — and twenty-nine doctors and surgeons.

We gather from an article in Science that the Conseil Supérieur de l'Instruction Publique has issued a decree, removing the restrictions upon the admission of American and other foreign students to the French universities, and giving them a status substantially similar to that accorded by the German universities.

The gold medal of the Royal Astronomical Society has this year been awarded to Dr. S. C. Chandler, of Boston. Dr. Chandler's astronomical labors have been exceedingly numerous; but that which has attracted most attention is an investigation showing the probability that some small fluctuations of latitude, which had been noticed in particular places, were due to a motion of the earth's axis causing the poles to describe circles, thirty feet in radius, round a center, the period of this motion being about fourteen months.

A recent improvement in the simple pendulum for purposes of measurement is reported as having been made by G. Guglielmo. The simple pendulum oscillates about its point of suspension in all directions. The compound pendulum rests on a knife edge, or essentially on two points some distance apart, and therefore oscillates always in the same plane. A bob suspended by two threads will do the same. But for some purposes it is highly desirable to have a body oscillating in the same plane and parallel to itself. Sgr. Guglielmo has accomplished this by taking two such bifilar pendulums and joining them by a horizontal rod placed in their plane of vibration. A very useful application of it is an anemometer designed on this plan.

The average weekly earnings of laboring men in the United Kingdom are computed in the latest Blue Book to be 27s. 7d., or £64 ($320) a year. But while this is the average, it is made up by balancing the wages of those who earn more and those who earn less; and it further appears that twenty-four per cent of the laboring men of the country have less than £1, or $5, per week.

Ludwig Rütimeyer, the distinguished naturalist, who died on the 26th of last November, was born at Biglen, in the Canton Bern, in 1825. His father was the parish clergyman, and the son intended to follow in his father's footsteps; but he was from his youth more interested in natural history than in theology. In 1848 he began the study of medicine, and for the rest of his life devoted himself to the study of comparative anatomy.