August 28, 1913] 



NATURE 



673 



that between two charged wires .is his starting point, 

 he builds up by simple processes the most important 

 practical cases. His paper concludes with a warning 

 against the frequent use of the idea of potential in 

 i asi - in which the simpler one of the electric field will 

 give all the required information. 



OUR ASTRONOMICAL COLUMN. 



The Origin of Solar Electricity. — Among the 

 many interesting papers concerning astrophysical 

 matters which appear in No. 8 of the Monthly Notices 

 of the Royal Astronomical Society, attention may be 

 directed to a convincing contribution to our know- 

 ledge of the agencies originating the vast solar elec- 

 trical phenomena demonstrated by the brilliant re- 

 searches effected at Mount Wilson. In a paper under 

 the above title Dr. J. A. Marker applies the results 

 of laboratory work conducted in collaboration with 

 Dr. G. W. C. Kaye at the National Physical Labora- 

 tory to the explanation of cosmical phenomena. This 

 experimental work has shown that at very high 

 temperatures the vapours in the tube resistance 

 furnace become highly conducting, and that under 

 the same condition most refractory substances emit 

 electricity carried by particles many limes the mass 

 of an atom of the substance. Calculations show 

 that the measured emissivity of carbon at about 3000° 

 C. would be ample to account for solar currents of 

 magnitude sufficient to give rise to the intense mag- 

 netic fields Professor Hale has shown to be probably 

 found in sun-spots. 



The True Form oe the Earth and its Internal 

 Constitution. — Dr. A. Veronnet contributes a dis- 

 cussion of these subjects to No. 13 of the Revue 

 Gendrale des Sciences. It is now known that this 

 •'somewhat irregular round body" on which we live 

 has a rough sort of tetrahedral shape, but mathe- 

 maticians must have a more generalised form, and 

 thus for them the geoid is an ellipsoid of rotation of 

 which the inverse of the eccentricity is about 297. Dr. 

 Veronnet criticises the various formula; which have 

 been suggested to represent the hypothetical generat- 

 ing curve, and has himself proposed a new one. By 

 considering the effect of variations of density and 

 velocity of rotation limits are determined for the 

 above-mentioned ratio, and it is shown that if the 

 above value, found by Helmert, is supported, then the 

 earth rotates as one piece. The author is also led to 

 make some interesting conclusions regarding the 

 eff ci of tides and causes of earthquakes. 



Cosmological Hypotheses. — At the Science Con- 

 gress held at Lourenco Marques, Mr. R. T. A. Innes, 

 of the Transvaal Observatory, dealt with this subject, 

 and added one hypothesis more which he referred to 

 as "the explosion hypothesis." He assumes that 

 matter will not indefinitely submit to continued reduc- 

 tion of volume under indefinitely increasing gravita- 

 tional pressure, but that a time will come when this 

 pressure will "break into the atomic structure of its 

 matter and cause explosions." By such explosions the 

 sun threw off the planets and the latter their satellites ; 

 in other stars they caused the formation of multiple 

 systems ; new stars are due to the eruptive outbursts 

 accompanying the explosions, and when on a smaller 

 scale and rhythmical they are responsible for the 

 phenomena of variable stars. Mr. Innes, we may 

 remark, has shown an inexplicable eclecticism in 

 choosing his foundation facts; for example, he has 

 ignored the harmonious results obtained by modern 

 workers on the temperatures of the individual stars, 

 but has selected a contrary opinion to the effect that 

 sotar type stars are hotter than the white stars. 



NO. 2287, VOL. 91] 



MAGNETIC SUR I 'E VS. l 

 ^pHE introduction tells us that this is the first of a 

 J- series of volumes to be published dealing with 

 the researches of the department of terrestrial mag- 

 netism of the Carnegie Institution of Washington, 

 founded in April, 1904. These volumes, while prin- 

 cipally on terrestrial magnetism, will contain memoirs 

 on allied subjects, such as atmospheric electricity. 

 The present volume treats of all the magnetic observa- 

 tions made on land by the department from the begin- 

 ning of its observational work in 1905 up to the end of 

 1910. These observations are directed towards the 

 accomplishment of one of the principal objects which 

 the department has in view, viz. the acquisition of 

 the data necessary for a general magnetic survey of 

 the earth. 



The first fifty pages deal with the general^ methods 

 of work, the selection and description of stations, and 

 especially with the field instruments and the taking 

 and reducing of observations. The observational in- 

 struments—magnetometers, dip circles, and dip induc- 

 tors — and auxiliary apparatus are handsomely, illus- 

 trated in plates 2 to 6. Much experience of field-work 

 has accumulated of late years at Washington, and the 

 instructions to observers merit the careful attention 

 of all interested in survey work. Pp. 51-6 

 introduce us to the results of the observations, which 

 are chronicled in the later part of the volume. On 

 p. S3 is a list of thirty-five observers whose work is 

 included. Amongst them are several eminent 

 foreigners, including Prof. Palazzo, of Rome, and 

 Profs. Beattie and Morrison, of South Africa, who 

 have observed for a time under the auspices of the 

 Carnegie Institution. The stations observed at 

 number almost 1300, of which more than 1200 are 

 outside the bound's of the United States. 



Of the continents, Africa shows the largest number 

 of stations, 386, the great majority of which were 

 occupied in 1907 and 1908 by Profs. Beattie and Mor- 

 rison. Of the 328 stations in North America, [89 

 were in Canada or Newfoundland, fifty-nine in Central 

 America, and nine in Greenland. In Asia there were 

 308 stations. Of these 142 were in China— occupied 

 mainly by Messrs. Edmunds and Sowers— thirty-seven 

 in Persia, thirty-two in Russian and eighty-one in 

 Turkish territory. The observations in Asiatic Turkey 

 were due mainly to Mr. Sligh, but partly to Mr. J. C. 

 Pearson. The latter gentleman seems to have taken 

 all the observations in Persia and in Asiatic and 

 European Russia, and most of those in Egypt. He 

 also observed in Canada, in European Turkey, at 

 Pola, Potsdam, and Kew Observatories, and was 

 amongst the crew of the surveying ship Galilee, who 

 observed in Japan, Australia, and New Zealand. His 

 experiences as a traveller should be of interest. Of 

 the remaining stations, 11 1 were in South America, 

 and 119 in numerous islands in the Pacific and Atlan- 

 tic Oceans. 



The tables of results, pp. 58-100, give for each 

 station the geographical coordinates, the date and 

 hours of observation, the observed values of magnetii 

 declination, inclination, and horizontal force, trie in- 

 struments used, and the observer's initials. Pp. 101- 

 120 contain interesting extracts from the reports 

 made by the several observers. The rest of the 

 volume is occupied bv minute descriptions of the 

 stations, to facilitate their identification. An artistic- 

 allv attractive feature is the reproduction in plates 1 

 and 7-10 of a number of fine photographs, showing 

 a selection of the stations occupied or scenes in their 

 neighbourhood. 



1 " Researches of the Department of Terrestrial Maenetism. Land Mag- 

 netic Observations 1905-10." By t.. A. Bauer, Director of the Departmerr. 

 Pp i8 = + ro plates. I Washington, D.C. : Published by the Carnegie Ins'i- 



