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SCIENCE-GOSSIP. 



CONDUCTED BY JAMES QUICK. 



Stereoscopic Radiography. — By means of a 

 recently designed apparatus, not only can foreign 

 bodies be traced in the human system, but their 

 places determined and their distances from a given 

 point of the skeleton found. It enables the operator 

 to take two radiographs in almost as many minutes, 

 develop, and examine them in a special stereoscopic 

 apparatus. This is brought about by using a vacuum 

 tube giving rapid records, and a stand which enables 

 the operator to take two radiographs of the same 

 object from two different, but precisely defined 

 foci. 



Thermal Ammeter. — By means of the following 

 instrument reliable measurements of the strength of 

 an electric current can be obtained. It consists of a 

 U tube filled with mercury, and with one of its 

 branches slightly drawn out in the middle. Into the 

 narrow portion is introduced a mercury thermometer. . 

 Two platinum electrodes are set in the branches of 

 the tube, and convey the current to be measured. 

 The heat developed bv the passage of the current is 

 almost all concentrated round the thermometer, and 

 the rise of the mercury in the latter within a given 

 time indicates the strength of current, as the heating 

 effect is directly proportional to the square of the 

 current. In an improved pattern of this instrument 

 the U tube is narrowed at its lowest portion, pro- 

 ducing a thin thread of mercury there. The thermo- 

 meter bulb encloses this thread, and thus measures 

 the heating without loss of radiation. The am- 

 meter will measure currents from I to o'05 amperes 

 within I or 2 per cent., and its readings .are very 

 constant. 



Volta's Apparatus. — The calamitous destruction 

 by fire of the historical apparatus of Volta is deeply 

 regretted by all the electricians of the Globe. The 

 fire occurred on July 8th, at the Volta Centenary 

 Exhibition at Como, and practically not anything was 

 saved. When the report of the loss reached London, 

 Professors S. P. Thompson, Ayrton, Perry, and 

 other prominent electrical engineers, who were 

 then assembled at a private function, at once sent 

 a telegram of deep sympathy to the Mayor of 

 Como. 



Phosphorescence at Low Temperatures. — 

 Experiments have been made to determine the precise 

 low temperature at which phosphorescent bodies lose 

 their luminosity, to regain it on heating. Specimens 

 of calcium and zinc sulphides exposed to the arc lamp 

 showed a diminution at — 20° or — 30° and their 

 phosphorescence disappeared entirely at about —50°. 

 When exposed to magnesium light, the luminosity 

 disappeared between — -jo'^ and — 90°. When 

 exposure to magnesium light is made at — 191°, the 

 temperature of liquid air, and the body is heated, 

 luminosity begins to appear at — iSo° and increases 

 as the heating proceeds. The exciting and emitting 

 processes are thus separated, and by means of rapid 

 heating it is possible to watch the first stages of 

 phosphorescence, which are usually masked by the 

 incident light. 



contributed by flora winstone. 



Bulletin de la Societe Royale Linneene 

 DE Bru.xelles (Brussels), May and June, 1899. — 

 This number contains an article b)' M. I'Abbe E. 

 Ouvray, on the vegetable parasites that attack the 

 order Rosaceae. He deals more especially with fruit 

 trees, giving a detailed account of the especial para- 

 sites attacking different species.. He concludes by 

 suggesting various remedies, the chief being the 

 following prescription : — 2 kgm. of sulphate of copper 

 and I kgm. of lime in 100 litres of water. Other 

 receipts are given, but in the opinion of M. Ouvray 

 this is the most effectual. The article is well worth 

 reading by those who are interested in the welfare of 

 their gardens and orchards. M. Gustave Riviere, 

 Professor of the Department of Agriculture in France, 

 writes on the characteristics of the phylloxera. 



Le Mois Scientifique et Industriel (Paris), 

 June, 1899. — This is the first number of a new maga- 

 zine, founded with the object of giving each month 

 reviews of the work that has been done in the different 

 branches of Science. We gather from the editorial 

 note that it is the intention of the management to in- 

 clude all branches. This number, however, deals 

 with Applied Science, with the exception of an article 

 on Agriculture. Amongst the subjects treated are 

 railways, tramways, auto-motors, navigation, indus- 

 trial chemistry, metallurgy, photography, and physical 

 research. The chemistry of minerals, organic and 

 biological chemistry, and several others are also treated. 

 An article on the history of wireiess telegraphy, by 

 M. A. Blondel, is promised for the next i.ssue. 



A Catalogue of Australian Coccidae, by 

 James Lidgett, has been reprinted from " The Wom- 

 bat " for May, 1899. It is a list of the various species 

 of this troublesome little group of plant parasites. 

 Those known in Australia up to the present day 

 number 1,119 species. Mr. Lidgett gives short 

 descriptions of the less generally recognised. 



L'EcHANGE Revue Linneene (Lyons), June, 1899. 

 — M. A. Carret continues his articles on V. Guillebeau 

 and his Entomological works. He analyses them with 

 great care, pointing out in what the}' are useful and 

 where the works have ceased to be valuable. M. 

 Viviand-Morel writes on some of the "Plants at 

 Fontainebleau." The article is largely a criticism of 

 M. Thurmann's theory that the distribution, or rather 

 arbitrary grow th and prosperity of plants in alien soil, 

 is due to the action of the minerals of the soil. M. 

 Morel illustrates his objections to this theory by 

 examples from the neighbourhood of Fontainebleau, 

 where, he points out, plants are found growing 

 in a soil which does not contain the minerals 

 necessaiy, according to M. Thurman, for their 

 growth. (July) M. Morel concludes his arlicle 

 on the Plants of Fontainebleau and M. Carret con- 

 tinues his analyses of Guillebreau's entomological 

 works. A .short note on a New Coleopteron is of 

 interest. It was found by Mr. J. Roger in Dahomey 

 and named by him Anthia hordasii, the specific name 

 being in honour of M. L. Bordas, the chief of the 

 Zoological Faculty at Marseilles, and well known for 

 his works on the Anatomy of the Coleoptera. 



