64 



NA TURE 



[May 17, 1906 



address to the Royal Microscopical Society. Renault's 

 work ranged over the field of fossil vascular cryptogams 

 and gymnosperms, within which the real triumphs of fossil 

 botany have been won. To Renault we owe the re- 

 construction of that unique family the Botryopteridea:, at 

 present regarded as the most authentic group of Palsozoic 

 frrns, also the extraordinarily perfect knowledge that we 

 possess of the gymnospermous Cordaiteee. Dr. Scott's 

 address, together with a list of Renault's more important 

 contributions, is published in the April number of the 

 Journal of the society. 



Dr. R. Perotti, writing in the MH dci Lincei, xv., 5, 

 describes observations on the distribution of nitrifying 

 bacteria in Italy. .Samples of soil were taken from various 

 districts, and cultures made by Beyerinck's method, and in 

 every case nitrifying bacteria were found in greater or 

 less abundance, the best results being obtained from Rieti, 

 Messina, and Cerignola. 



Prof. Giacinto M.artorelli has had the rare fortune to 

 obtain a specimen, believed to be the first, of Ross's polar 

 gull {Rhodostethia rosea, Macgill.) from the Mediterranean, 

 killed in the neighbourhood of Sardinia. The specimen in 

 question reached him on January 10 of this year in the 

 flesh, though decomposition was setting in. It appears to 

 be a young bird, being 30 centimetres in length, and 

 possibly this may account for its being found so far from 

 its northern haunts. The discovery is announced in the 

 Kcndiconto del R. Istituto Lombardo, xxxix., 4, and the 

 specimen has been stuffed and given to the Turati 

 collection. 



Dr. F. Eredia, of the Central Meteorological Office at 

 Rome, has published in the official reports an account of 

 a fall of dust on February 6. The occurrence was con- 

 sidered to be of sufficient importance to issue circulars to 

 various observatories requesting particulars of the fall ; the 

 reports show that the dust was observed in Sicily, Lower 

 Calabria, and other places, accompanied by thunderstorms, 

 rain or hail, and strong south-easterly and south-westerly 

 winds. The cyclonic conditions existing at the time would 

 favour the conveyance of dust from Africa over the 

 Mediterranean in the upper regions of the atmosphere, and 

 although no analysis appears to have been made, the dis- 

 tribution of barometric pressure and other conditions seem 

 10 confirm the African origin of the phenomenon. 



The director of the Mauritius Observatory contributed 

 to the eighth International Geographic Congress a useful 

 paper on the climate of Pamplemousses. The results of 

 Ihc observations at Port Louis for 1S60-6 were communi- 

 cated to the British Association in 1867 by the late Dr. 

 .Meldrum ; those commenced at Pamplemousses in 1874 form 

 the basis of the present paper. The following are the 

 mean annua! and absolute extreme values of some of the 

 meteorological elements :— air temperature 73°4, 94°-7 in 

 December, so°-8 in June; humidity 75-1 per cent., 98-5 per 

 cent, in January, 34.0 per cent, in November; resultant 

 wind velocity 9-2 miles per hour ; the maximum velocity 

 recorded in an hour was 103-3 miles (old factor 3) on April 

 29, 1892. Cyclones are said to be of immense benefit to 

 the island, as one of the principal sources of rainfall. 

 Taking an area of 20° square, of which Mauritius occupies 

 nearly the centre, 237 cyclones were recorded in the years 

 ■854-1903. The greater number occurred between December 

 and March, and not one was recorded between June and 

 September ; their occurrence appears to be most frequent 

 five years after, and least frequent one year before, the 

 epoch of minimum solar activity. 

 NO 1907, VOL. 74] 



The principal article in Concrete and Constriictionat 

 Engineering (vol. i.. No. 2) is by Captain Sewell, of the 

 United States Army. It deals with the introduction of 

 reinforced concrete in the United States, and is a com- 

 mentary on the various systems and methods of applying; 

 this material adopted in that country. The article is illus- 

 trated by views and details of important buildings. 



At the last meeting of the Institution of Mechanical 

 Engineers an interesting paper was read by Mr. Louis 

 Greaven on petroleum fuel in locomotives on the Tehuan- 

 tepec National Railroad of America. It gives the actual 

 results of a year's experience, and the information should 

 prove of service to others who contemplate adopting oil 

 fuel in railway working. 



In a paper read before the Birmingham section of the 

 Institution of Electrical Engineers on April 25, Dr. D. K. 

 Morris and Mr. G. A. Lister proposed a standard test for 

 transformers and transformer iron. The method involves 

 but one set of connections, three instruments, and the 

 norma! supply, and necessitates the use of two similar 

 transformers. It is a modification of that first described 

 in 1S92 bv .Ayrton and Sumpner, and is an application of 

 the Kapp-Hopkinson or differential method of testing direct- 

 current machines. The behaviour of a transformer when- 

 loaded at various power factors is, they find, best con- 

 sidered by means of a regulation diagram which they 

 have constructed. The short-circuit test can equally welf 

 be carried out with the transformer core excited. The 

 three-point wattmeter method is probably the most accurate 

 means of measuring power factor and current when carry- 

 ing out single-phase tests on transformers or motors from 

 a three-phase supply. By bringing the supply to the middle 

 point in the testing transformer when carrying out the 

 differential test, symmetrical conditions are obtained, thus 

 permitting of a normal determination of the various losses. 

 By varying the voltage only and taking wattmeter read- 

 ings the core loss of a transformer may be separated into 

 hysteresis and eddy-current loss by the method of the total 

 index. Wattmeter readings in combination with the three- 

 point method serve as the best means of measuring the 

 temperature rise in heating tests. The method of constant 

 induced voltage affords a ready means of finding the true 

 hysteresis loss, and is probably the best way of testing 

 iron samples. 



OUR ASTRONOMICAL COLUMN. 



Comets 19066 and i9o6f. — A set of new elements for 

 the orbit of comet 1906b is published by Herr M. Ebell 

 in No. 4087 of the Astronomische Naclirichten. An 

 ephemeris for alternate days is also given, extending from 

 May 4 to July 7, and shows that this comet is still in the 

 southern part of the constellation Leo, about half-way 

 between t and v Leonis. It is moving very slowly in a 

 south-eastern direction, its present brightness being about 

 0-5 of that at the time of its discovery. 



A set of new elements for comet 1906c, computed by 

 Miss Lamson, of the U.S. Naval Observatory, appears in- 

 No. 4086 of the same journal. 



The Astronomical and .Astrophysical Society of 

 Amf.rica. — ."^t the seventh annual meeting of this society,- 

 held in December last at New York, -some forty papers on 

 astronomical subjects were submitted. 



Short abstracts of thirty-three interesting papers are given 

 by Prof. H. Jacoby in No. 586 of Science, and amongst 

 those which have not been noted previously in these 

 columns may be mentioned the following : — A note on 

 Prof. Burnham's forthcoming catalogue of double stars; 

 a brief description of the vacant regions of the sky, by 

 Prof. Barnard ; an announcement concerning the publication 



