5i6 



NATURE 



[October 20, 1910 



energy, but of transforming energy already existent in the 

 atmosphere in order to produce rain. He referred also 

 to the difficulty of explaining the return to earth of the 

 outward flowing negative electricity, and mentioned, in 

 conclusion, the relation between the radio-active contents 

 of the air and its previous history ; air which had travelled 

 over the sea was much less radio-active than that which 

 liad been for some time over the land. 



Dr. Chree in his reply emphasised the fact that during 

 rainfalls there are fluctuations of potential, and in con- 

 clusion urged the necessity of observations over much 

 wider areas before many of the problems of atmospheric 

 electricity could be settled. 



At this stage the section divided. In the department 

 of cosmical physics Dr. W. Schmidt, of Vienna, com- 

 municated an interesting description of a new instrument, 

 the variograph, designed by him for measuring short 

 waves in atmospheric pressure. He showed records 

 obtained by it at Innsbruck and Vienna. Conditions at 

 Innsbruck, especially in the winter months, are very 

 favourable for the production of waves, the cold air in 

 the valley lying beneath a warmer upper layer. By 

 recording with two instruments i km. apart. Dr. Schmidt 

 deduced that both progressive and standing waves occurred, 

 the period of the latter being considerably greater than 

 that of the former ; in a particular case the periods were 

 3-5 minutes and 9 minute.s respectively, and the record 

 showed the interference of the two sets of waves. Dr. 

 Schmidt showed, too, that in Fohn weather, when regular 

 waves were recorded, the regularity ceased when the 

 Fohn wind actually broke through the cold layer and 

 blew at Innsbruck, proving that the layer of discontinuity 

 was essential to the formation of the waves. In some 

 cases regular waves preceded by several hours the occur- 

 rence of line-squalls, corroborating Russell's observations of 

 cirrus clouds. 



Mr. Dines spoke on the records from the upper atmo- 

 sphere obtained during the passage of the earth through 

 the tail of Halley's comet. The traces obtained by Mr. 

 Dines in ordinary cases are of two kinds, one in which 

 the up and down curves coincide, the other in which 

 loops are formed. The traces at the time of the coinet 

 showed an abnormally large proportion of the second kind, 

 but it was not possible to say if the peculiarity was due 

 to the comet or to the type of the prevailing weather. 



Dr. Nicholson in a paper on radiation pressure in 

 cosmical problems show^ed thai more extended calcula- 

 tions do not confirm Schwarzschild's results in detail, but 

 the general character of these results is preserved. 



Miss Margaret White showed a series of slides giving 

 the results of the hourly balloon ascents made from Man- 

 chester in March.' The results corroborated in their main 

 features those obtained in June, 1909, and communicated 

 at the Winnipeg meeting. 



Mr. Stupart gave some results of an inquiry into the 

 vertical temperature gradients in Canada in the winter 

 months. The principal conclusions were : — (1) that in 

 cold winters in Manitoba the temperature increased up- 

 wards, the mountains being warmer than the plains ; 

 (2) that in warm winters the mountains were colder than 

 the plains, and the vertical gradient approached the 

 adiabatic value. 



Mr. Gold communicated the results of an investigation 

 into the effect of radiation on H . (he height, and T^ 

 the temperature of the advective region. So far as radia- 

 tion is concerned, the variation both in the temperature 

 and in the absolute humidity of the atmosphere tend to 

 increase the value of H,. with approach towards the 

 equator, but their efTects on T. are in opposite directions. 

 .\ necessary condition for the existing state of affairs is 

 that the atmosphere should be very nearly transparent to 

 low temperature radiation for considerable regions in the 

 spectrum. 



Prof. F. G. Baily described a sensitive bifilar seismo- 

 granh for recording undulatory movements of the earth's 

 surface of short period. By a system of multiplying levers, 

 great sensibility is attained, and it m.ay be expected that, 

 when the present experimental instrument is replaced by a 

 final form exposed in a suitable chamber, valuable results 

 will be obtained. 



In the department of general physics, which sat simul- 

 taneously with the above, Mr. Twyman described, on 

 NO. 2138, VOL. 84] 



behalf of Prof. C. F^ry, a successful attempt to simplify 

 the long-range spectrograph to make it suitable for indus- 

 trial investigations concerning metals, alloys, &c. The 

 principle of auto-collimation is employed, a 30° quartz, 

 prism being traversed twice by the beam of light. By 

 giving suitable curvatures to the two sides of the prism 

 it acts also as the lens-system, producing a sharp spectrum 

 on a cylindrical surface, exactly as with a curved reflect- 

 ing grating, and with a much less inclination of the plate. 



In a paper on the magnetic field produced by the motion 

 of a charged condenser through space, Mr. W. F. G. 

 Swann discussed the possibility of detecting the presumed 

 field by means of a rotating coil, even though the impossi- 

 bility of detecting it by a magnetic needle is admitted.. 

 His analysis seemed to indicate that if the specific induc- 

 tive capacity may be looked upon as a quantity absolutely 

 continuous throughout the dielectric, a magnetic flux 

 through the coil should exist, but that if the dielectric 

 action is to be explained by electric charges or doublets, 

 no resultant magnetic flux is to be anticipated. Experi- 

 ments made by the author gave a null effect, and this is 

 taken to support the doublet theory of dielectric action. 



Three papers were read by Prof. J. C. McLennan on 

 behalf of the authors, who are his students at Toronto. 

 In the first Mr. \ . E. Pound details the results of experi- 

 ments on the secondary radiation from carbon at low- 

 temperatures when bombarded by the a rays from 

 polonium. Fifty per cent, more is produced at the 

 temperature of liquid air than at atmospheric temperature. 

 This is attributed to the much larger amount of air 

 occluded in the carbon. The second paper, by Prof. 

 McLennan and Mr. N. Macallum, was on a resolution of 

 the spectral lines of mercury by a high-grade echelon 

 spectroscope made by Messrs. .'\. Hilger. \ number 

 of slides were exhibited showing the components of the 

 green and blue mercury lines and their resolution under 

 the action of a magnetic field. The third paper was by 

 Mr. W. T. Kennedy, on the active deposit obtained when 

 the emanation from actinium is allowed to diffuse freely 

 between two parallel plates placed about 2 millimetres 

 apart over the actinium salt, the plates being maintained 

 at a difference of potential of 250 volts. The deposit is 

 found to reach a maximum for a particular gas-pressure. 

 It was concluded that the proportionate amount of emana- 

 tion which possesses a positive charge varies with the 

 pressure. 



Dr. H. S. .Mien followed with an important summary 

 of our present knowledge of photoelectric fatigue. This 

 was accompanied with a bibliography, which has been 

 ordered to be printed in extcnso. This was succeeded by 

 an interesting paper by Drs. W. Makower and S. Russ 

 and Mr. E. J. Evans on the recoil of radium B from 

 radium A. The magnitude of the effect observed was of 

 the order to be expected if radium B carries the atomic 

 charge of electricity and if its atomic w'eight is 214, as is 

 to be expected on the transformation theory of radio-active 

 processes. 



The proceedings on Wednesday, September 7, began 

 with a very interesting account by Sir Norman Lockyer 

 of his work on stars and their temperatures. The spectra 

 of the hottest stars indicate that in them we have to 

 deal simply with hydrogen and with another form of 

 hydrogen produced from it : but helium runs hydrogen 

 very close as one of the constituents of a star's earliest 

 atmosphere. Iron, even in a proto-form, enters into a 

 star's atmosphere at a much later stage, and iron such as 

 we know it in our laboratories at a later stage still. The 

 general conclusion from Sir Norman's work is that we 

 are able to establish a palaeontology of chemical sub- 

 stances. 



Prof. W. M. Hicks sketched some of the evolutions of 

 a vortex, and was succeeded by Dr. C. Chree, who read 

 a critical paper on the rate of propagation of magnetic 

 disturbances. Dr. Bauer, of the Carnegie Institution, 

 believes he has established as a fact that the so-called 

 " sudden commencements " of magnetic storms are pro- 

 pagated at such a rate as to take, on an average, about 

 3J minutes to go round the earth, and he believes that 

 the cause of these disturbances is a peculiar form of over- 

 head electric current in the plane of the earth's equator 

 due to charged ions, the height of which, on the average, 

 is about fiftv miles. Dr. Chree considers that the theory 



