4o8 



NA 1 URE 



[June 



1^ 9 



and the previous highest record for May is 237 hours, in 

 igoO, wliilst the previous highest record for any nioiUli in 

 tlic year is 2bi hours, in July, igoo. At Greenwicli the 

 duration of bright sunshine for May was 326 hours, which 

 is 140 hours more than the average, and in April there 

 was an excess of 103 hours, making a total excess of 

 243 hours for the two months. In May there were seven 

 days with more than fourteen hours of bright sunshine, 

 and there have only been two days without sunshine during 

 the last two months. At some places in the south of 

 lingland the sun was shining in May for 350 hours. The 

 aggregate duration of sunshine since the commencement 

 of the year is largely in excess of the average over the 

 whole of England, the excess for the twenty-one weeks 

 amounting to more than 200 hours in the south-east of 

 Unglanil." 



An important contribution to the study of the upper air, 

 by Dr. W. Koppen, is published in .his dem Archiv licr 

 deutschen Sccii'nrtc, vol. xxxi., part i., entitled " Three 

 Years' Simultaneous Meteorological Kite Ascents near 

 Hamburg, Berlin, and St. Petersburg." In order to throw 

 light on the lateral extension, of the warm and extremely 

 dry strata met with in kite ascents, on the 'conditions of 

 Iheir occurrence and disappearance, and on their effect 

 .,11 weather changes, the author has collated, side by side, 

 the results for each day during the period December, 1903, 

 to November, 1906, on loS diagrams, each containing ten 

 days, and showing temperature, wind direction and velocity, 

 and low conditions of humidity. The general discussion 

 of this very useful synoptic material is left for future 

 work ; the author nevertheless' directs attention to several 

 interesting points. The inversions of temperature are 

 specially noticeable, particularly those which occur suddenly, 

 where the warm stratum borders almost immediately on 

 the cold layer beneath ; the temperature gradients in these 

 remarkable inversions are often very large, and mostly 

 occur in lale autumn and in winter. The increase of wind 

 velocity with height naturally differs with the direction 

 and with season ; all the curves show a rapid increase up 

 to 500 metres, after which it becomes more gradual. The 

 diagrams only include altitudes up to 4000 metres; between 

 the ground and 3000 metres, at Hamburg, the general 

 mean of the velocity (irrespective of direction) in metres 

 per second is 16-7 in the summer half-year and 17 in the 

 winter half-year, while at Berlin the velocities are hi and 

 12-8 respectively. These special points are discussed by 

 the author in considerable detail. 



In a pamphlet of twenty-seven pages published by 

 Gauthier-\'illars, of Paris, M. Jacques Boyer has 

 recently given, an admirable sketch of the work done of 

 late years, especially in France, in the artificial produc- 

 tion of precious stones. With respect to the formation of 

 true rubies, some of which are quite undistinguishable from 

 the natural stones, new and interesting information is given 

 concerning the work accomplished by the successors of 

 Fr-imy — Fell, Verneuil, Dioner Wyse, Maiche, Michaud, and 

 Marc Paquicr — with photographs of the actual apparatus 

 employed in the latest manufactures. While the repro- 

 duction of the ruby, of perfectly naturdl colour, has been 

 so successful, much greater difficulty has been experienced 

 in trying to imitate' the sapphire, the actual source of the 

 colour in this gem being more doubtful. M. Boyer, how- 

 ever, clitims that excellent results have now been obtained 

 by M. Disclyn and M. Louis Paris. In the reproduction 

 of the varieties of quartz used as gems, it is interesting 

 to learn that the different tints of the amethyst have been 

 producett by the action of radium on the uncoloured 



NO. 2066, VOL. 80] 



niin'.T.iI : ;in(.l with regard to the opal and emerald informa- 

 tion is given, ihougli no results of commercial value have 

 as yet been obtained. The work concludes with an account 

 of what has been effected in the w.iy of producing the 

 diamond by artifici.tl means, photographs of Moissan's 

 electric furnace .and other apparatus being given. A 

 bibliography at the end of the paper is useful, but the 

 work, though it contains much valuable and interesting 

 information — sometimes on points upon which there has 

 been much concealment — cannot be regarded as in any 

 sense exhaustive. 



Prof. J. Tr.wbe, of Charlottenburg, has always beer, 

 one of the most pronounced opponents of the dissociation 

 theory of solution, and in the April number of Ion ho 

 shows how the idea of cohesion pressure, that is, the 

 attraction exerted by the inolecules of the dissolved sub- 

 stance on the molecules of the solvent, may be used to ex- 

 plain the properties of solutions, whether these are met 

 with in physical, chemical, or physiological fields. Prof. 

 Traube's paper should pave the way to a thorough dis- 

 cussion of the question of solutions. In the same number 

 Dr. V. Kurbatov, of -St. Petersburg, shows the inadequacy 

 of the . electronic theories of the conduction of . electricity 

 in metals, as stated in various forms by Profs. Drude, 

 Lorentz, and Sir J. J. Thomson, to explain the facts 

 observed. lie gives an outline of his own theory which 

 is based on the electronic constitution of matter, but he 

 does not justify the assumptions on which he founds it. 

 The translation of this paper is far from perfect. 



SiN'CE flame spectra were first discovered two explana- 

 tions have been offered as to their nature. According to 

 one, they are the direct result of chemical reactions going 

 on in the llame — the reduction of the metallic salt, in the 

 opinion of Pringshelm — while the other regards them as 

 the effect of (ho normal oscillations of the atoms at the 

 high temperature of the flame. In the latter case the 

 speeds of the atoms are distributed according to the law 

 of Maxwell, In the former there will be regions of chemical 

 action in which the speeds will be in excess of the normal. 

 The experiments of Pringshelm, and more recently those 

 of Fredenhagen, seem to support the chemical luminescence 

 theory, while the work of M. E. Bauer, described In the 

 .'\pril number of Lc liadium, lends strong support to the 

 pure temperature explanation. M. Bauer has measured the 

 radiation and absorption of a large Meker flame for sodium 

 light and for the long rays produced by repeated reflec- 

 tions from fluorite (" reststrahlen "), and finds that 

 Kirchhoff's law is followed, while the temperatures of the 

 flame calculated from the two sets of observations agree 

 very closely. The conclusion seems forced on us that 

 temperature is the essential factor in the production of 

 flame spectra, and if chemical action accounts for any of 

 the radiation it does so only indirectly. 



The new 300-ton universal testing machine recently 

 installed by Messrs. W. and T. Avery, Ltd., in the civil 

 engineering laborator\' of the University of Birmingham 

 is described and illustrated In the Engineer for May 21. 

 The machine is of the horizontal type, and can take 

 exceptionally long specimens — under tension to a maximum 

 stretched length of .33 feet 6 inches, and under compression 

 up to a maximum length of .30, feet. An hydraulic 

 pressure of 1000 lb. per square inch Is supplied from an 

 accumulator charged by a motor-driven pump, and 

 advantage is taken of the city main pressure of 85 lb. 

 per square inch for returning the straining cylinder ram 

 and for low load tests. The weighing arrangement 

 consists of a bell-crank lever connected to a second lever 



