i68 



NA TURE 



[Ai'RiL 8, 1909 



discussion of observations at over-sea stations forms an 

 important part of the useful work of the Seewarte ; 

 returns from twenty-one places were received, irrespective 

 of the stations in German East Africa, the results for 

 which are being prepared for publication, as in previous 

 years. The departments dealing with the supply and 

 verification of instruments and the preparation of hand- 

 books for seamen also show great activity. 



A SIMPLE method of illuminating opaque objects is 

 described by Mr. J. E. Stead, F.R.S., in the Journal of 

 the Royal Microscopical Society (February). With low- 

 power objectives a cover-glass is placed at an angle of 

 45° in front of the objective, and reflects light on to the 

 object from an electric lamp. For higher powers the 

 reflector is always placed in a slit in the objective above 

 the lens. 



Dr. Emilio Oddone, applying the methods of Koves- 

 ligethy and Rudsky to the recent Sicilian earthquake, 

 computes the depth of the epicentre at about 9 kilometres. 

 The corresponding result for the Calabrian earthquake of 

 1905 was 7 km., and the author refers to Mallet's result 

 of 10 km. for the Neapolitan earthquake of 1857, pointing 

 out, however, that other methods lead to much higher 

 values. Dr. Oddone 's note is published in the AHi dei 

 Lincei, .xviii., 4. 



In a communication to the Atti dei Lincei, xvii. (2), 12, 

 Prof. Augusto Righi integrates, for a particular case, the 

 equations of motion of an electron describing an orbit 

 about an ion in a magnetic field. The case considered is 

 that in which the mass of the ion is so large in com- 

 parison with that of the electron that its velocity is prac- 

 tically uniform, and the plane of the orbit is perpendicular 

 to the lines of magnetic force. The problem reduces to 

 a simple one in particle dynamics, and gives for the 

 relative orbit a conic described about the focus. The 

 author discusses the conclusions to be derived regarding 

 the effects of the field in assisting or impeding the separa- 

 tion of the electron from the ion in the case of collisions. 



No. 5, vol. xxviii., of the Astrophysical Journal contains 

 a paper, by Messrs. G. Duffield and R. Rossi, on the 

 emission spectrum of silver heated in a carbon-tube furnace 

 in air. Previous work by Mr. Duffield having led to the 

 conclusion that a more complete knowledge of the band- 

 spectrum of silver was desirable, the authors employed a 

 similar furnace to that used by Dr. King in his investiga- 

 tions of various spectra at the Pasadena Observatory. The 

 large number of lines observed suggested that the spec- 

 trum was not due to silver alone, but comparative experi- 

 ments with tin and other metals brought out none of the 

 lines. One or two of the flutings observed, in the region 

 ^ 5370 to \ 5750, are of doubtful origin, but no opportunity 

 of obtaining definite results presented itself. None of the 

 lines, however, occurs in the arc or in the spark spectrum 

 of silver, although Hartley detected three faint lines in 

 that region of the flame spectrum. The general conclusion 

 is that the oven spectrum of silver differs markedly from 

 the spectra of silver produced by other methods. The 

 experiments were carried out in the physical laboratory of 

 the Manchester University. 



Ion for February devotes a dozen pages to a report, by 

 Prof. R. Gans, of the University of Tubingen, on recent 

 advances in ferromagnetism. The subject-matter is 

 arranged under the following heads : — methods of measure- 

 ment, permeability and hysteresis, influence of frequency, 

 alloys, crystals, influence of temperature, strain and 

 NO. 2058, VOL. 80] 



magnetisation, molecular theories of magnetisation. Refer- 

 ences to more than 100 papers published during the years 

 1907-8 are given, and a glance through the list shows 

 that the great bulk of them deal with questions which 

 have arisen in practice, and that very little has been done 

 towards a scientific explanation of magnetic processes. 

 This undue devotion to practical problems the author 

 regrets, and he expresses the view that it is to the interest 

 of all that the purely scientific side of the subject should 

 not be neglected in the quest for material with low 

 hysteresis losses. 



No. 43 of the occasional publications of the Conseil 

 international pour I'E.xploration de la Mer contains an 

 account of the measurements of the compressibilities of 

 pure water and of sea-water undertaken by Dr. V. W. 

 Ekman, of the central laboratory at Christiania, at the 

 request of the council. The method depends on the 

 measurement of the quantity of mercury forced by pressure 

 into a glass vessel containing the water, through a narrow 

 tube connecting the vessel with another containing 

 mercury and open to the pressure. In the deep-sea instru- 

 ment the mercury forced in is tilted into a pocket by 

 inclining the vessel. In the laboratory instrument a 

 weighed amount of mercury is placed in the outer vessel, 

 and makes an electric circuit until it is forced past a 

 platinum contact in the narrow tube connecting the two 

 vessels. The_ compressibility of the glass of the vessels 

 was known, and that of the mercury was found by a 

 separate experiment. The results are given in the form 

 of an expression for the compressibility in terms of tempera- 

 ture and concentration which is valid between 0° C. and 

 20° C, and up to pressures of 600 atmospheres. 



The new calcium-carbide factory at Odda, on the 

 Sondrefjord, Norway, forms the subject of an interesting 

 article in Engineering for March 26. This factory is the 

 property of the Alby United Carbide Factories, Ltd., and 

 has been organised by a British company with British 

 capital in order to ensure a regular supply of calcium 

 carbide, the absence of which was interfering with their 

 business as manufacturers of a special, acetylene plant. 

 The potentialities of Norway for industries requiring much 

 power are very great, many waterfalls being splendidly 

 placed for the production of hydraulic power by means of 

 turbo-generators. In the present case, a hydro-electric 

 power installation has been already constructed giving 

 23,000 E.H.P., and 75,000 to 80,000 horse-power are avail- 

 able in the water supply. The total producing capacity of 

 the new factory is 32,000 tons of calcium carbide and 

 12,500 tons of nitrolim (for use as a fertiliser) per annum. 

 Care has been taken not to interfere with the amenities of 

 the district, which is a tourist resort. The water-collecting 

 area is 380 square kilometres, from which hundreds of 

 small streams discharge into the Ringedalsvand. As there 

 is only a distance of 3-5 kilometres between this lake and 

 the fjord where the power-station is situated, it will be 

 seen that the conditions are very favourable for the con- 

 struction of a pipe-line to the power-station. 



The current number of the Zeitschrift jiir physikalische 

 Chemie contains a paper, by J. G. L. Stern, on the appli- 

 cation of the platinum resistance thermometer to the 

 determination of molecular weights in fused potassium 

 nitrate as a solvent. The modified form of thermometer 

 used was capable of estimating temperature differences of 

 o''-o4 at a temperature of 335° C. The sulphates, chlorides, 

 and nitrates of the alkalies and alkaline earths were used 

 as solutes. The values obtained for potassium nitrite 



