378 



NA TURE 



[February 20, 1902 



On the other hand, the crowd of hydrogen or mercury atoms, 

 by virtue of molecular motion and inter-collisions, act as gases. 

 Whilst their mean free paths are conditioned by the degree of 

 exhaustion, there may be amongst them a certain number of 

 actual free paths differing widely on each side of the mean. 

 Under the influence of the electromotive force, and at the right 

 degree of exhaustion, these atoms arrange themselves in groups,' 

 while the rushing swarm of electrons driven from the negative 

 pole meet them and render them visible. According to 

 J. J. Thomson, the mass of an electron is about the i,7ooih 

 part of that of the hydrogen atom, and as these masses start 

 from the negative pole in a vacuum lube with a velocity of the 

 order of half that of light, it is easy to see that their heating, 

 phosphorescent and mechanical power must be stupendous. 



The basis of the electron, as I foreshadowed in 1879 in the 

 case of radiant matter, is probably the same in all cases — the 

 protyle from which the chemical atoms were assumed to be 

 formed. 



On the two-fluid theory, the electrons constitute free negative 

 electricity, and the rest of the chemical atom is charged 

 positively, although a free positive electron is not known. It 

 seems to me simpler to use the original one-fluid theory of 

 Franklin and to say that the electron is the atom or unit of 

 electricity. Then a so-called negatively charged chemical atom 

 is one having a surplus of electrons, the number depending on 

 the valency, whilst a positively charged atom is one having a 

 deficiency of electrons;. Difierences of electrical charge may 

 thus be likened 10 debits and credits in one's banking account, 

 the electrons acting as current coin of the realm. 



SCIENTIFIC WORK OF THE GERMAN 

 ANTARCTIC EXPEDITION:- 



■nPHE head of the German Antarctic Expedition, Prof. Dr. 

 Drygalski, has sent from Cape Town to the home autho- 

 rities a number of full reports on the work which had been 

 carried on by the expedition up to the date of their despatch. 

 As is well known, the ship, which had been specially built for 

 the expedition, was long overdue at Cape Town, and her pro- 

 tracted non-appearance gave rise to some anxiety. We give the 

 following extracts from the oflicial report, which will shortly 

 appear, in order to furnish evidence of the activity of the staff, 

 and of the reasons for the great protraction of the voyage. 



In the scheme of operations for the expedition, it had been 

 arranged that visits to two land stations should be made during 

 the voyage to Cape Town, in order to determine, by fresh com- 

 parisons with the absolute magnetic elements at those land 

 :stations, the changes in the magnetic character of the ship since 

 its determination at Kiel before sailing. The magnetism of a 

 new ship is always subject to changes in course of time, but 

 these changes are more especially caused by change of magnetic 

 latitude as the ship passes from one hemisphere to the other. 

 With this object, the following places were selected as ap- 

 parently desirable : — The Cape Verdes or Madeira, north of the 

 magnetic equator, and Bahia or .Ascension to the south of it. 



1 In an address delivered before the Institution of Electrical Engineers, 

 January 15, tSgi, I save an outline of a theory of stratifications in rarefied 

 ga.ses. The following quotation renders my meaning clear: — "If, in 

 any much-freiiuented street, at some time when the stream of traffic run.s 

 almost equally in both directions, we take our stand at a window from 

 which we can overlook the passinR crowd, we shall notice tfcat the throng on 



the footway is not uniformly distributed, but is made up of knots— we might 

 almost say blocks — interrupted by spaces which arc comp.-iratively open : we 

 nny easily conceive in what manner these knots or groups are formed: 

 .some few persons walking rather more slowly than the average rate 

 slightly retard the movements of others, whether travelling in the .same or 

 in an opposite direction. Thus a temporary^ obstruction is created. The 

 passengers behind catch up to the block and increase it, and those in front, 

 jj.Tssing on unchecked at their former rate, leave a comparatively vacant 

 space. If a crowd is moving: all in the same direction, the formation of 

 these groups becomes more distinct. Hence mere differences in speed suffice 

 to resolve a multitude of passengers into alternating gaps and knots. 

 Instead of observing moving men and women , suppose we experiment on 

 little particles of some substance, such as sand. If we mix tne particles 

 with waier in a horizontal tube and set them in ^rhythmical agitation, we 

 shall see very similar results, the powder sorting itself with regularity into 

 alternate-heaps and blank spaces. If we passto yet more minute substances, 

 we observe the behaviour of the molecules of a rarefied gas when submitted 

 to ari induclion current. The molecules here are free, of course, from any 

 caprice, and simply follow the law I seek to illustrate, and though 

 originally in a state of rampant disorder, yet under the influence of the 

 electric rhythm, they arrange themselves into well-defined grcups or stratifi- 

 cations."— /<>«»■<(.. of the Inst. Electrical Engineers, vol. xx, p. 10. 



2 Based upon an Aitlcle in Dry Int:, Herlin, January 25. 



After consultation with the magnetician of the ship. Dr. F. 

 Bidlingmaier, I had selected Porto drande in .St. X'incent and 

 Ascension. If, for any reason. Ascension proved to be inac- 

 cessible, it seemed advisable to adopt the usual plan, on board 

 ship, and determine the deviation by swinging the ship on 

 eight different courses in the open sea. During our stay at 

 Porto Grande, which lasted until .September ii- 16, the magnetic 

 observations were our principal business, and we succeeded in 

 determining, on board the ship, the deviations in the Magnetic 

 Declination, Total Force, and in Horizontal and \'ertical Force 

 due to her magnetism. 



I myself landed, with two assistants, and set up a tent near 

 the spot where the shore magnetic observations were being 

 carried on, in order to secure time observations to rate our 

 chronometers and watches, and also to make some observations 

 of the force of gravity. Owing to the weather, we could make 

 no astronomical observations. 



My orders for the next part of the voyage were to cross the 

 equator on the i<Sth meridian, and then to make for Ascension. 

 The object of the first position was to verify the sounding of 

 7370 metres (4030 fathoms) [the greatest depth on the line], 

 which had been obtained by the French man-of-war La 

 Romatuhe in 0° It' S. and iS^ 15' \V. .Vs this figure is not 

 mentioned on the British charts of soundings, nor in the 

 recent critical representation of sea depths, by Prof. Dr. Supan, 

 I therefore wished to trace its possible connection with the 

 great depths of the Brazilian basin. 



The vi.sit to Ascen.sion was to attain the objects above named. 

 It was evident enough that the carrying out of this plan would 

 present some difficulties, for the usual sailing track to the Cape 

 (which was best for our ship, owing to the low power of her 

 engines, which would not allow of steaming against the S.E. 

 trade with its accompanying sea) crosses the equator far to the 

 westward, probably as far as the 25th meridian. A visit to 

 Ascension would entail our steering a south-easterly course im- 

 inediately on leaving the Cape Verde, so as to be able to make a 

 south-westerly course to the island under .sail. The course in- 

 dicated was to be first tried and tested as to whether it would take 

 too much time. We crossed the belt of calms under steam, between 

 the two trade winds. In this swell the Gauss rolled, at times 

 very heavily, so that much glass or other breakable articles in 

 the laboratory came 10 grief, while the ship, under sail, even 

 with a stiff breeze and a good deal of sea, had been remarkably 

 steady. This swell retarded our progress considerably, as of 

 course our speed was greatly reduced. This was aggravated by 

 increased fouling of the bottom. As the ship was very low in 

 the water, the screw well, through which the .screw and rudder 

 could be lifted, on meeting ice, so as to preserve them from 

 damage, may have contributed to the prolonijation of the 

 voy.age. In short, we proceeded very slowly along the pre- 

 scribed track, where the wind failed us, and the currents at 

 least gave no help, though the engines worked perfectly, and 

 gave promise of a very satisfactory performance whenever we 

 should come into a slate of sea checked by the presence of ice. 



AH these impediments retarded us with enhanced insensity 

 when we met the S.F. trade on the line. This was very fresh 

 (and we should have liked to have had a similar force in the 

 N.E. trade), but we could make no use of it, as it was dead 

 ahead on our course for Ascension, and it brought wiilv it a 

 trying [swell and current. The rate of the ship got less and 

 less, and at last stopped entirely on October 5. In ihese cir- 

 cumstances, as time was getting on (we crossed the line a few 

 days after the entry of the sun into south declination on 

 October 1, so that we ran directly from the norrticrn into the 

 southern summer), it seemed therefore desirable to reconsider 

 our plan and give up the .'Vscension visit entirely, and so on 

 October 6 I decided to do this and use the existing S.E. trade 

 for a run to the Cape, starling on that day. As .soon as we 

 changed our course we made at once a speed of six or seven 

 knots. On October 7 wc disconnected the engines and made 

 sail, but the wind did not last. On October 9 the S.E. wind 

 died away, and these light winds continued, with some slight 

 exceptions, up to Cape Town. The Gauss always made very 

 short daily runs, so that wc had a very long passage. The 

 light winds and fair weather were the cause, as we had only 

 one storm, November iS-20. just at the end of ihe voyage. 

 We were naturally obliged to husband our coal so as not to 

 lighten Ihe ship loo much. 



On October 30, the after steam capstan was connected with 

 Prof. \'ansch(>ffen's vertical net, which was at a depth of 



NO. 16S6, VOL. 65] 



