26o 



NA TURE 



[December 31, 1908 



tifularly the great interest now generally taken in seismo- 

 log-ical studies to the hope that these may aid in solving 

 I he problems inherent to the constitution of the interior 

 of the globe. In the course of his remarks he said that 

 the great improvement in self-recording instruments has 

 enabled us to determine the trajectories of the seismic 

 waves, to study their reflection, refraction, dispersion, and 

 absorption ; but he remarks that we shall never be able 

 to avoid the terrible scourge of the earthquake, nor even 

 to foretell it. Modern discoveries, however, have led us 

 to consider the interior of the globe to be formed of a 

 solid nucleus, with a density and rigidity greater than that 

 of steel. This nucleus is enveloped by a rocky crust, but 

 between this crust and the metallic nucleus lies, at a great 

 depth, the layer of plastic matter, of high temperature, 

 •which e.tplains volcanic phenomena and their localisation. 



We have received from the Royal Observatory of 

 Belgium the results of recent balloon ascents made at 

 Uccle, including those arranged for by the International 

 Commission for Scientific Aeronautics, from July 27 to 

 .\ugust I. The observatory was very unfortunate during 

 this period; the records of two ascents were wilfully 

 destroyed, and only one ascent, that of July 30, reached 

 a considerable altitude, 15-2 kilometres, where the tempera- 

 ture by M. Hergesell's metallic thermometer was 

 ~.i<3°v ('■ The minimum reading of the up trace was 

 -()9°-2 C. at 13-2 kilometres. In the British Isles twenty- 

 eight ascents were made during the above period, twelve 

 of which were on account of the Meteorological Office. 

 The preliminary results of the British series were com- 

 numirated to the Royal Meteorological Society by Mr. 

 C J. r. Cave on December 16. The average height 

 reached was 16-4 kilometres, the highest being 23 kilo- 

 metres, at Pyrton Hill, Oxfordshire. The records of all 

 the balloons recovered, except one, showed the existence 

 of the isothermal layer. 



Prof. I.ar.mor pointed out several years ago in his 

 •• .Ether and .Matter " that the fundamental facts of optics 

 and electrodynamics, those of aberration in particular, re- 

 quire us to assume that the aether does not partake to 

 any sensible extent in the motion of matter through it. 

 On this hypothesis there should, however, be certain 

 modifications in the optical or electrical actions of bodies 

 on each other according to the direction in which the 

 tether is sweeping past them. Such effects have been 

 sought for and not found, and the negative results led 

 Profs. Lorentz and Fitzgerald to suggest as explanation 

 that the bodies themselves undergo changes of shape when 

 they move through the .xther which accurately compensate 

 these effects. More recently Prof. Einstein has shown that 

 the "principle of relativity," according to which only 

 relative motions of bodies with respect to each other can 

 produce observable effects, leads to the same law of change 

 of shape, and Prof. H. A. Bumstead, in an interesting 

 article in the November number of the American Journal 

 of Science, is disposed to accord it a position analogous 

 to that of the second law of thermodynamics. He applies 

 It in succession to the torsion pendulum, the gravitation 

 pendulum, and to several problems of gravitation, and 

 shows that it leads to a slight modification of the Law of 

 giavitalion and to consequences which ought to be capable 

 of detection astronomically. 



As a supplement to liivista Mariltima (Rome) for 

 November are published two papers, by Prof. Guido Cora, 

 on geograjihy and oceanography during the nineteenth 

 ".entury. In thi' second paper Prof. Cora gives a short, but 

 •comprehensive, review of the chief problems of oceano- 

 NO. 2044, VOL. 79] 



graphy from its foundation to the present time. The 

 papers should be valuable as guides to work accomplished 

 in geography and oceanography during last century. 



Mr. C. Bakek, of High Holborn, London, has for- 

 warded a copy of the 1909 issue of section iv. of his cata- 

 logue. The catalogue is divided into four parts, dealing 

 respectively with aids to vision, prismatic and other optical 

 appliances, projection apparatus, and meteorological and 

 allied instruments. We have also received the current issue 

 of Mr. Baker's classified quarterly list of second-hand 

 instruments which he has on sale or hire. 



OUR ASTROSOMICAL COLUMN. 



Search for an Ultra-Xeptunian Planet. — Following 

 the recent interesting discussion by Prof. Forbes at the 

 Royal .Astronomical Society, of the probable existence of 

 a planet beyond the orbit of Neptune, there is an interest- 

 ing note by Prof. K. C. Pickering in No. 4292 of the 

 Astronotnische Nachrichlan (p. 323, December 18). 



In this note Prof. Pickering mentions that as the result 

 of an investigation, an abstract of which was read at the 

 .■\merican Academy of Arts and Sciences on November 11, 

 Prof. W. H. Pickering finds evidence of the existence of 

 an ultra-Neptunian planet, which at the epoch 1909-0 will 

 be located approximately in R..-\. 7h. 47m., dec. ■f2i°. 

 Photographs of this region have already been taken with 

 the 24-inch Bruce telescope at Arequipa, and the Rev. 

 J. H. Metcalf is also employing his 12-inch doublet for the 

 same research. 



.'\s this region is now easily accessible, Prof. Pickering 

 asks that other astronomers, having the use of suitable 

 instruments, should join in the search. Should the pro- 

 posal be accepted by any number of workers, it is proposed 

 that a syslematic study of this portion of the ecliptic might 

 be organised. 



Further Orservations oi- MoREiiot:sE's Comet, 1908c. 

 — In No. 24 of the Comples rendus (p. 1263, December 14I 

 M. J. Guillaume gives some further interesting details 

 concerning the remarkable changes which look place in 

 the form of count hioSc as observed at the Lyons Observa- 

 tory. 



On October 24 the nucleus was seen to be elongated 

 and to have a granular appe;irance with a small stellar 

 condensation, of about the thirteenth magnitude, towards 

 the eastern exlrcmity of the head. The light of a star, of 

 the tenth or eleventh magnitude, appeared to be .augmented 

 as the head of the comet passed before it until it reached 

 the eastern edge, when sudden diminutions of brightness 

 occurred at interv.ils of several .seconds. 



Rem.-irkable oscillations of the brightness of various 

 parts of the coma were also observed, and on November 17, 

 when the field of the telescope was artificially illuminated, 

 the comet disappeared with a star of the ninth magnitude. 



The same number of the Comptes- rendifs also contains 

 the results of observations of the comet's position, made at 

 Ihe Toulouse Observatory between October 2 and 13. 



The Figure or- the Sun. — In No. 26 of the Contribu- 

 tions from the Observatory of Columbia University, New 

 York, Prof. Charles Lane Poor brings together in a 

 general discussion the results hitherto obt.-ilned from in- 

 vestigations de.iling with thi- figure of the sun, and its 

 possible variations. 



Some of the earlier results were directh' contradictory 

 in their statements as to whether the equatorial or the 

 polar diameter was the longer, whilst later results indicate 

 that although there may be a fluctuating difference. Its 

 magnitude is insufficient to show definitely. 



Prof. Poor, summing up the general results of the pre- 

 sent investigation of meridian, hellometer, and photo- 

 graphic measures, concludes that the exact shane of the 

 sun is not known, but the generally accented Idea that It 

 is a sphere is at least open to question. All the measures 

 show a departure from the spherical form, but the differ- 

 ence between the various radii probablv does not exceed 

 o''-2.;. 



