June 9, 1904] 



NA TURE 



'43 



reasons for fixing the date of upheaval subsequent to the 

 Bronze age and anterior to the Roman occupation. — Dr. 

 R. H. Traquair exhibited a skull of the great extinct ox 

 (ZJos taurus, var. primi genius), and certain remains of rein- 

 deer, which had been found in the grounds of Dundas Castle, 

 Dalmeiy. The skull was very large, and indicated a great 

 stretch of horns. — Prof. .A. Crichton Mitchell gave certain 

 preliminarv results he had obtained on the rate of con- 

 vective loss of heat from a surface exposed to a current of 

 air. .\ thin strip of platinum foil formed the one branch 

 of a Wheatstone bridge, which was constructed so as to be 

 able to carry very powerful currents. The current through 

 the strip was strong enough to raise it to the temperature 

 of incandescence, and was measured accurately on a galvano- 

 meter placed suitably in the circuit. The strip was enclosed 

 in a tube through which a blast of air was drawn by means 

 of a large fan worked by a gas engine. The velocity of the 

 air was measured directly in each case. The experiment 

 consisted in finding the resistance of the strip, and there- 

 fore its temperature, for given values of heating current 

 and velocity of air. It is evident that for moderate veloci- 

 ties of air current the strip will, for a particular value of 

 electric current passing along it, be cooled more or less 

 according as the air current is greater or smaller. The 

 results so far obtained indicated that even in still air a 

 large part of the cooling was due to convection. It was 

 hoped that the experiments would lead to important inform- 

 ation as to the relative amounts of convection and radiation 

 when a surface was cooling in the air. 



May 16. — Sir John Murray in the chair. — Dr. J. Halm 

 read a paper on a cosmic theory of the diurnal and long- 

 period changes of terrestrial magnetism and their possible 

 connection with seismic phenomena and the displacement 

 of the earth's axis of rotation. On the assumption that the 

 :itmosphere is a feeble electric conductor set in oscillation 

 by the thermal and gravitational action of the sun and 

 moon, an expression was obtained for the diurnal variation 

 of magnetic potential. This contained as a factor the 

 variation in height of a mass of air. But on the assump- 

 tion that the air was in an average state of convective 

 equilibrium, the principles of thermodynamics led to the 

 result that this time variation in height was proportional 

 to the time variation of the air temperature at the earth's 

 surface. Hence was deduced the formula \' = a sin 2<t>d6;d\, 

 where \' is the magnetic potential, (j> is the latitude, \ the 

 longitude, (/ the temperature, and a a constant. The 

 equipotential curves so obtained showed a remarkable re- 

 semblance to -Schuster's curves deduced from magnetic 

 observations, the main difference being a lag in longitude 

 (equal to time) of the real curves as compared with those 

 deduced from theory. The ne.xt step in the argument was 

 to consider the possible strains which might result from 

 this diurnal variation in magnetic distribution, and the 

 conclusion w'as that such strains would cause a slight 

 bulging on the side next the sun. This one-sided tide 

 agreed with the indications of the horizontal pendulum 

 as found by Ehlert, and with the recent measurements of 

 change of direction of plumbline. It was easy to see that 

 the change in declination of the sun would give rise to 

 seasonal effects, and the periodicity indicated for various 

 latitudes agreed in a suggestive manner with the seasonal 

 curves of seismic activity in these latitudes. By an appli- 

 cation of the same principle of convective equilibrium. Dr. 

 Halm showed that the daily oscillation of the barometric 

 pressure could be represented as the sum of two terms, of 

 which one depended on the change of temperature from the 

 mean and the other on the second differential coefficient 

 of the temperature at the surface. The constant factor 

 multiplying the latter term is the same along a latitude 

 parallel, at least to a first appro.ximation, but the multiplier 

 of the former term depends on the character of the locality 

 according as it is maritime, continental, or mountainous. 

 The general theory advanced brought into connection not 

 onlv meteorological and magnetic phenomena, but also 

 seismic activity, change of latitude, and displacement of the 

 earth's axis, and all as a result of solar radiation acting 

 on the earth's atmosphere. It was natural to search for 

 the eleven-year period in these variations. A careful tabula- 

 tion of Omori's recent statistics of earthquakes in Japan 

 from the earliest recorded cases showed an undoubted 



eleven-year period, and gave another argument in favour 

 of the idea that seismic activity was influenced by magnetic 

 changes. The paper touched upon several other astro- 

 nomical and meteorological problems. 



Paris. 

 Academy of Sciences, May 30. — M. Mascart in the chair. — 

 The chemical effects of light. The action of hydrochloric 

 acid upon platinum and gold : .M. Berthelot. Pure 

 gold and platinum are slowly attacked by fuming hydro- 

 chloric acid in the presence of light ; control experiments 

 in which these metals were treated with hydrochloric acid 

 and kept in the dark gave no metal in solution. In the 

 presence of manganese chloride the amount dissolved was 

 nearly doubled. — Study of the solubility of silicon in silver. 

 On a variety of crystallised silicon soluble in hydrofluoric 

 acid : H. Moissan and F. Siemens. Silicon is much more 

 soluble in fused silver than in lead or zinc. The crystal- 

 lised silicon found in the solidified metal contains a certain 

 proportion of an allotropic variety of silicon which is 

 soluble in hydrochloric acid. The experimental results are 

 expressed in the form of a curve, showing the relation 

 between the total silicon dissolved as a function of the 

 temperature, and also of that portion which is soluble in 

 hydrofluoric acid. — On the formation in nature of vanadium 

 minerals : A. Ditte. — On the use of stereoscopical images 

 in the construction of topographical plans : A. Laussedat. 

 — The effects of small oscillations of external conditions on 

 a dependent system of two variables : P. Duhem. — On a 

 phenomenon analogous to phosphorescence produced by the 

 ii-rays : E. Bichat. A copper plate is exposed to the action 

 of a bundle of »i-rays of definite wave-length, obtained from 

 a Nernst lamp after refraction through an aluminium prism. 

 The secondary rays emitted by the plate are analysed by 

 means of a slit and an aluminium prism, making use of 

 a phosphorescent screen. It is found that, in accordance 

 with Stokes's law, the secondary radiations are of greater 

 wave-length than the primary radiations from which they 

 are derived. — Magnetic observations at Tananarive : P. 

 Colin. Tables of the absolute values of declination and 

 inclination for the year ending April, 1904. — The synthesis 

 of a series of tertiary alcohols, starting from cyclohe.xanol : 

 Paul Sabatier and Alph. Mailhe. It has been recently 

 shown that cyclohexanol can be readily obtained in quantity 

 from phenol by the action of hydrogen and reduced nickel. 

 By treating with alkyl-magnesium compounds, this sub- 

 stance yields a series of tertiary alcohols. The mode of 

 preparation and the physical properties of a number of 

 these alcohols are given, the reaction appearing to proceed 

 equally well with both fatty and aromatic compounds. — 

 The hydrographic study of the coasts of France, from 1902, 

 to 1903 : M. Laportc. — On the foundations of a systematic 

 theory of spherical functions : Niels Nielson. — On the 

 universal joint : L. Lecornu. — On the simultaneous, 

 emission of the n- and Hj-rays : Jean Becquerel. From, 

 the variation in the intensity of a feebly phosphorescent 

 screen under the influence of the n-rays with the angle at 

 which the screen is viewed, the conclusion is drawn that 

 under the influence of the n-rays such a screen emits n-rays 

 normally and n^-rays tangentially. E.xperiments in sup- 

 port of this view are given. — The action of anesthetics on^ 

 the sources of the Hj-rays : Julien Meyer. Sources of ^ 

 iij-rays, like those of the n-rays, are affected by anaesthetics. 

 — On a new' method of obtaining photographs in colours : 

 Auguste and Louis Lumiere. The method described in the 

 present communication is based on the use of coloured 

 particles arranged in a layer on a glass plate ; this is 

 covered with a suitable varnish, and finally with a layer 

 of sensitive emulsion. The plate thus prepared is e.xposed 

 through the back, developed, and the image thus prepared 

 inverted, giving the colours of the original photograph on 

 looking through it. — On a new regulator allowing of the 

 control of the vacuum in a Crookes's tube : M. Krouchkoll. 

 .^ side tube is blown on to the bulb containing some glass 

 wool. After the tube has become hard through use, it is 

 only necessary to warm the glass wool slightly, when 

 sufficient air is given off to restore the tube to its original 

 condition. — Acetylenic aldehydes. New method of prepar- 

 ation ; the action of hydroxylamine : Ch. Moureu and R. 

 Delange. The acetylene hydrocarbon is heated for twenty- 



NO. 1806, VOL. 70] 



