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Page:Popular Science Monthly Volume 44.djvu/590

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THE POPULAR SCIENCE MONTHLY.

structions to forward them to the nearest Swedish consul. The manuscripts have not been fully examined.

Prof. Frankland says that while the virility of many bacteria can be greatly reduced by successive cultivations, and the poisonous effects of such active bacteria as those of typhoid and cholera can be intensified by passing them repeatedly through the bodies of animals which at first offered great resistance to their pathogenic action, this increase in toxic effect can not be produced by artificial cultivation, and it has not been found possible to convert a harmless organism into a pathogenic one.

A curious case of resuscitation of an optical image has been described by Prof. T. Viguoli from his own experience. After a railway journey in a bright sun and two days' walking in the heat, he looked from the room in which he was engaged in conversation upon a balcony standing out in the bright sunlight. Early in the morning two days afterward, while lying awake in bed, he saw upon the ceiling an exact reproduction of the balcony, in all its colors and details. The image disappeared on closing the eyes, and reappeared on opening them again. Its appearance was not changed when it was regarded with one eye, looking with either alternately. It was interrupted by putting the finger in front of the eye, and responded in every respect to the usual features of ordinary vision. A cage of birds which hung upon the original balcony appeared, swinging as the real cage did.

What is undoubtedly the first publication of Asa Gray, although it is not included in the published lists of his writings, has been sent to Garden and Forest. It is a catalogue of the indigenous flowering and filicoid plants growing within twenty miles of Bridgewater, Oneida County, New York. It consists of nine pages, is dated January 1, 1833, or when the author was just in his twenty-fourth year, and is contained in the forty-second annual report of the Regents of the University of the State. It is also included in Prof. Britton's List of State and Local Floras of the United States and British America, where it is entered under Onondaga County.

Concerning his experience with horseshoes of aluminum, M. Japy reports that as that metal is four times lighter than iron a complete outfit of shoes of it will weigh no more than a single iron horseshoe. Horses accustomed to iron shoes when shod with shoes of aluminum imagine themselves barefooted, and are as careful in planting their steps as if they were unshod. The shoes open out as the hoof expands, and consequently never cramp it. An aluminum horseshoe will last from forty to sixty days, according to the composition of the alloy and the kind of work done by the horse. M. Japy concludes that aluminum can be utilized in shoes for race and carriage horses, and that it may be of service in the treatment of diseases of the hoof. It should, however, be used-only by persons experienced in working the metal.

An instrument which he calls a formenophone has been invented by a French engineer, M. E. Hardy, for detecting the presence and estimating the proportions of gaseous impurities of an atmosphere by the sound they give in a pipe. It is based upon the principle that air passing through an organ pipe gives a definite and constant tone, while if any other gas is mixed with it the tone varies according to the gas and the quantity of it. Two instruments of similar construction are used—one arranged so that pure air, the other that the air to be measured shall be made to pass through pipes of identical construction.

The importance of taking thorough precautions in the case of animals dying of infectious disease is newly illustrated in an observation made by the Russian Diatroptoff. The water of a particular well was supposed to be the cause of an epidemic outbreak of anthrax among certain sheep. No contamination was found in the water, but the mud at the bottom of the well contained a microbe which produced anthrax on being inoculated into a sheep. The germs are supposed to have percolated through the soil to where they were found. The anthrax among the sheep ceased on the well being closed.

In a paper on Grinding and Polishing, Lord Rayleigh, after referring to the accuracy with which optical surfaces can be worked, said that the operation of grinding did not produce scratches on a glass surface, but that pits were cut into an otherwise plane surface by it. A surface so ground, when used for a lens, gave excellent definition, but great loss of light by irregular reflection. To remove this defect the lens had to be polished, by which operation the pits were gradually removed. He gave reasons for believing that in the process of polishing the glass was worn off molecularly, whereas grinding removes fragments of the glass. He found that in polishing a certain thin disk of glass a thickness equal to about six wavelengths of yellow light was removed. It was easy to remove as small a depth as half a wave-length by means of hydrofluoric acid if proper precautions were taken.

Molds differ from bacteria, according to Prof. Frankland, in their action, and produce an oxidation, or burning up, instead of fermentation.

A new section, that of physiology, has been formed in the British Association. It is the ninth section, and will be designated by the letter I.