492 



NATURE 



\_Sept. 2 2, 1 88 1 



On MagndU DUtiirhanu-s, by Prof. W. G. Adams, F.R.S. 

 — The author, in considering magnetic disturbances, stated that 

 certain facts about them had long been known ; from the obser- 

 vations of Gauss in 1S34 the disturbing power was found to 

 iicrease in northern latitudes ; it was also found that the appear- 

 ance of a di>lurbance occurred in several places at the same 

 instant, but with grc^at differences of results. The force seemed 

 to originate at a certain point in the interior of the earth, and 

 the direction of the disturbing force seemed constant, yet great 

 differences were observable at places not remote from one 

 another. Sabine found that the^e disturbances had daily and 

 yearly variations from their mean values, and that they have an 

 eleven-year period corresponding to the appearance of spots 

 upon the sun. It has been shown by observations that magnetic 

 disturbances and electric currents on the earth are related ; these 

 electric currents in the earth have commonly been attributed to 

 changes of te Jiperature. The month of March, 1879, was 

 chosen for a comparison of the photographic records of mag- 

 netic disturbances, and records for the whole mouth were sent 

 from Lisbon, Coimbra, Stonyhurst, Vienna, St. Petersburg, and 

 Bombay in th^ northern hemisphere, and from Melbourne and 

 the Maiu'itius in th^ southern hemisphere. Taking the disturb- 

 ances on March 15-16, 1879, as an instance, we see that soon 

 after 10 a.m. Greenwich time on the 15th, a disturbance-wave 

 liappens, which shows first a diminution and then an increase of 

 horizontal fjrce at St. Petersburg, Vienna, Kew, and Lisbon, 

 and also at Mel lourne in Au>traUa. At 9.30 p.m. of the same 

 day a magnetic storm begin-, and continues for about an hour. 

 It is felt in the northern and southern hemispheres. At all sta- 

 tions in Europe the horizontal force is increased in the first part 

 of the storm, and then diminished. At Lisbon the vertical 

 force is first increased and then diminished, and at St. Petersburg 

 and Stonyhurst there is a diminution in the vertical force at the 

 same time as at Lisbon. Regarding the declination needles, we 

 tind that at St. Petersburg, Melbourne, and Bombay the de- 

 clination westward is first increased and then diminished, \\'hereas 

 at Kew and Lisbon the motions are in opposite directions. At 

 Bombay and Mauritius, near to, but on opposite fides of, the 

 equator, the declination needles are deflected opposite ways. If 

 we assume that by magnetic induction the earth's magnetism is 

 altered, the position of the magnet ^vhich would cause tlie 

 disturbance must be such that its pole, which attracts the 

 marked end of our needle, must lie at the beginning of the dis- 

 turbance to the east of Kew and Lisbon, to the north of Vienna, 

 and to the north-west of St. Petersburg ; tlie Lisbon vertical 

 force curve also shows it to be below the surface of the earth. 

 Hence an inductive action equivalent to a change of position of 

 the north magnetic pole towarls the geographical pole would 

 account for these changes. The strengthening and weakening 

 of a magnet with its north po'e to the 1 orth on the me-idian of 

 Vienna might account for magnetic changes ol>served between 

 9.30 and 10.30 at night, Greenwich time, on March 15, 1S79. 

 In attemiiting to explain this disturbance by currents of elec- 

 tricity or discharges of statical electricity in the air above the 

 needles, we must imagine that at first there is a strong cuiient 

 from tlie south-west over St. Petersburg, from the west over 

 Vienna, and from the north-west over Kew and Lisbon, the 

 vertical force needle at Lisbon showing that the current from the 

 north-west lies somewhat to the east of Lisbon ; that at the 

 Mauritius this current is from the north, and at Bombay from 

 the south. Thus we must imagine that a ciu'rent of electricity 

 jiasses down from the north-west to the south-east, going on 

 towards the east over Vienna, and towards the north-east over 

 .St. Petersburg. This must be kept up very much along the 

 sime line throughout the first part of the disturbance, and then 

 the current must be altered in strength in the same manner at 

 all stations. An examination of the principal disturbrnces at 

 Kew and at St. Petersburg seems to show that (i) a dimii ution 

 ia the horizontal force is accompanied by greater easterly deflec- 

 tions of the declination needle at St. Petersburg than at Kew ; 

 (2) increase of horizontal force is accompanied by greiter 

 westerly dellcctions at St- Petersburg than at Kew, or is some- 

 times accomoanied by a westerly deflection at St. Peterslmrg 

 and an easterly deflection at Kew. Only moderate disturbances 

 have ah'eady been ccn;idei-ed, and the author now ti-eats of a 

 much larger magnetic storm which began at 10.20 a.m. Green- 

 wich time on August 11. This storm may be divided into three 

 storms; one lasting fi-om I0.20 on the nth to i a.m. on the 

 I2th ; a second from 11. 30 a.m. on the 12th to 7.20 a.m. on the 

 13th ; and the third from 11.50 a.m. on the 13th to 7 to S a.m. 



on the 14th of August. The first storm began on August 11, 

 at the same instant at all stations. There is a decided similarity, 

 especially in the horizontal force curves, throughout the first 

 part of this storm, and certain points in it stand out prominently. 

 The deflections are alike at Lisbon, Kew, Vienna, St. Peters- 

 burg, and after the first very sudden deflection at Toronto also. 

 The greate-t effect is produced at St. Petersburg ; tlie similarity 

 between the large disturbances at Vienna and Toronto, in 

 Canada, places diflfering about six and a half hours in time, is 

 remarkable. About 11.45 P-™- ^"'1 2.40 p.m. there are very 

 remarkable points of agreement. From about 4.30 p.m. to 8 

 p.m. Greenwich time, i.e. from about 11 a.ra to 2.30 p.m. 

 Toronto time, the deflections are opposed at Toronto and at 

 Vienna or Kew, This would point rather to so'ar action as the 

 cause of the distui'bance. At 9 p.m. the disturbances are all in 

 the same direction, but about 11 p.m., whilst St. Petersburg 

 agrees in direction with the others in a vei^ violent phase of the 

 storm, at Toronto the direction of the deflections is reversed, 

 and thi; reversal of curves continues until about the end of the 

 first of the three storms. The second storm, the most remark- 

 able of the three, began about 11.30 a.m. on the 12th, and 

 lasted until the next morning. At Toronto the line goes off the 

 edge of the paper on which the photographic record is taken. 

 At Vienna and Melbourne the motion is so rapid that the plate 

 is not sensitive enough to receive the impressions. At 12.20 

 midday, the time of greatest disturbance at Lisbon and at Zi-ka- 

 Wei near Shanghai in China, two places nine hours different 

 and nearly in the same latitude, the vertical force is increased in 

 precisely the same fashion. At St. Petersburg the change in the 

 horizontal force ^va5 one thirty-fifth part of the whole horizon- 

 tal force, and the total force w as changed to about one-eightieth 

 part of its full value. These magnetic changes are so large as 

 to be quite comparable, as we see, with the earth's total force, 

 so that any cause which is shown to be incompetent from the 

 nature of things to produce the one can hardly be held to 

 account for the other. 



The number of mathematicians who attended the meeting was 

 very remarkable, and among the foreigners present may be men- 

 tioned Messrs. Halphen, Chemin, Rudolf Sturip, Cyparisso; 

 Stephanos, and W. Woolsey Johnson (Annapolis, L".S.). A 

 separate mathematical department ^\"as formed, which met on 

 three days, and more than thirty papers on pure mathematical 

 subjects were read, many of them being of great interest. Prof. 

 Halphen made a communication on Steiner's theorem relative to 

 the positions of the centres of conies passing through three given 

 points, and gave an elegant extension of the theorem to distin- 

 guish the cases in which the three points lay on the same or 

 opposite branches of the curve. He also made communications 

 on the subject of linear dift'erential equations and hypergeometri- 

 cal series ; and in a fourth pa|ier he considered the number of 

 aspects in which points in a plane may be viewed. He showed 

 that two points may be thus viewed in six ways, that four points 

 can be viewed in nine ways, and illustrated this by a diagram, 

 and extended the theorem to five points Prof. Sturm com- 

 municated an elaborate memoir on curves of double curvature, 

 relating to the researches of Cayley and Halphen, which was 

 ordered to be printed in extcnso among the reports. M. Ste- 

 phanos read several papers, in one of which he showed that the 

 different homogiaphies which exist upon a straight line, and 

 which are triply infinite in number, may be identified with the 

 points of space. A simple and beautiful representation of the 

 particulars of these systems was thus obtained. 



The other papers inchided communications by Prof. Cayley, 

 On the Transformation of Elliptic Functions, and on Abel's 

 Theorem; by Prof. H. J. S. Smith, On the Differential Equa- 

 tions satisfied by the Modular Equations, and on the Theory of 

 the Multiplier in the Transformation of El !i fie Functions ;hy 

 Mr. J. VV. L. Glaisher, On the q-Series in Elliptic Functions ; 

 by Dr. Hirst, On Consequences of the Second Order and Second 

 Class ; and by Prof. R. S. Ball, On the Application of non- 

 Euclidean Space to a Problem in Kinematics, and an Exten- 

 sion of the Theory of ' Screws to the Dynamics of any Material 

 System. 



SECTION B— Chemical Science 

 The Present State of Chemical Nomenclature, by Prof. A. W. 

 Williamson, Ph.D., F.R.S. — The author stated there were per- 

 haps few departments of science in which such definite principles 

 had been adopted, and to a great extent this ajiplied to the 



