KNOWLEDGE 



[January 1, 1896. 



admitted in the description which did not directly throw 

 light on the structuio of the country, or which was not 

 a direct ontconio of the action of gcogvajihical conditions. 

 Great engineering works which have changed tlio natural 

 lines of communication of a district would of course bo 

 noticed, as well as the economic resources of the country. 

 The whole would conclude with an aljiliabotical index 

 containing every name on the sheet, with the latitude, 

 longitude, and elevation of all important points. 



This would form, if properly carried out, the greatest 

 geographical work of the coming century, and would be 

 completed by a discussion according to natural districts, 

 such as Wales, the Pennine Chain, the Lake District, the 

 Weald, the Fens. Afterwards these could bo digested into 

 an raithoritative geography of the whole country, written 

 ■w-ith a perfect unity of plan and aim, and embodying the 

 practical application of the principles of geography. 



The preparation of such an ideal work would involve a 

 great amount of geographical research, and would afford 

 an opportunity for founding a school of British geographers, 

 who would study their science practically and at first hand. 

 The conditions of all research are the same. Abstraction 

 on the part of the worker from all but the one aim being 

 pursued is essential, and adequate training in the methods 

 to be employed is necessary before beginning permanent 

 work. These conditions are inconsistent with earning a 

 living by doing work which is demanded by the public. 

 The pulilic does not yet realise either the value or the 

 essential conditions of research. Practically, only a 

 University professorship, in which research is the main 

 object and lecturing is subordinate, would meet the case, 

 unless a man of private means took the matter up, or it were 

 undertaken under Government. Such work, to be efficient, 

 would require to be steady, continuous, and unfettered. 

 The results could not be sensational, and, very probably, 

 would not be popularly appreciated ; but participation in 

 such research would be a noble training for students who 

 do not desire to become specialists, for no educative 

 influence is so powerful as personal association with a 

 professor engaged enthusiastically in scientific work 

 involving research in which every student may help. 



I have enlarged upon a single instance, not because it is 

 the only one that might be adduced, but because it may 

 serve to suggest to those who have not thought of the 

 matter before what sort of science geography is, what it 

 may become, and how the impress of British thought may 

 yet accompany the record of British work in the scientific 

 literature of all nations. 



THE GREAT RED SPOT ON JUPITER. 



By E. Walter Maunder, F.E.A.S. 



OF all our planetary neighbours, Jupiter, the easiest 

 to study, offers us the most numerous problems. 

 First of all comes the striking contrast between 

 its enormous mass and low density ; next, there 

 is the difficulty of understanding how its atmo- 

 sphere can have thegreatdepth which it evidently possesses 

 without the lower layers becoming compressed to more 

 than metallic density ; thirdly, the great variety in the 

 rotation period of the different markings of the planet ; 

 fourthly, the continual changes which the details of the 

 apparent surface present ; fifthly, a certain strong per- 

 sistency about the planet's appearance as a whole; and 

 lastly, summing in itself every variety of enigma, there is 

 the great red spot. 



Its history is sufficiently well known. Public attention 

 here in England was first drawn to it by Mr. V. C. Dennett, 



who stated in the Fvqiish 'Mechanic of November 22iid, 

 1878, that ho had then had it under observation for fully 

 four months. But other observers had had it in view long 

 before this notice appeared. M. Niesten, at Brussels; 

 Prof. Pritchett, at Glasgow, Missouri, U.S. A; M.Trouvelot, 

 at Cambridge, Mass. ; the observers at the Dun Echt 

 Observatory ; Herr Tempel, at Arcctri ; and others also had 

 been attracted by it during the summer of 187H. The 

 next year it was the subject of general attention amongst 

 astronomers, and not without reason. Its deep colour — a 

 strong brick-red — its great size, its well-marked outline and 

 definite shape, made it a most attractive object. Here 

 there was something relatively stable and permanent ; 

 something more substantial than the weird succession of 

 beautiful but evanescent cloud-forms which follow each 

 other so swiftly across the Jo\ian disc. This was just what 

 had been wanting to Jupiter before. The charm of variety 

 had always been his ; there had been also a certain stability 

 about the arrangement of his belts ; and his detailed 

 markings had been formed after a few distinct types : but 

 there had been nothing of such strongly marked 

 individuality of character and such persistence of life till 

 the red spot appeared. 



The first question which its discovery aroused was, 

 " Has it been seen before?" Clearly it had not been so 

 conspicuous before, but a fair amount of evidence was 

 forthcoming that, for eight or nine years prior to 1878, the 

 spot had been seen occasionally. Thus, Mr. H. C. 

 Kussell, at Sydney, observed what appears to have been 

 the spot in 1876 ; Mr. Terby and Mr. Corder represented 

 a similarly placed but smaller spot in 1872 ; and in 18G9 

 and the following year Mr. Gledhill remarked in the same 

 latitude, not, indeed, the red spot as such, but a hollow 

 ellipse, not unlike the aspect it was destined to wear some 

 fifteen years later, during the progress of its fading from 

 its greatest distinctness. 



There may have also been earlier records, but from 1878 

 to the present time it has been under observation at each 

 succeeding opposition ; and certainly the impression it 

 then produced upon the most experienced observers of the 

 planet was that it was quite a new order of feature. We 

 may take it, then, as practically a new object in 1878 ; new, 

 at all events, as to its definiteness. 



That definiteness it did not long retain. In the succeed- 

 ing oppositions it showed itself as continually growing 

 paler and paler. Its outline remained much the same, 

 but the interior of the spot appeared filled with white 

 material, or the white cloud formed above it. By the end 

 of May, 1883, only the faintest, feeblest ghost of the spot 

 remained, and observers feared it was lost to them. It re- 

 appeared, however, during the next opposition, though still 

 very faint, and it has undergone some minor fluctuations 

 in brightness since. In 1891, for instance, it presented 

 again the appearance of an elliptical ring, the interior 

 being lighter and whiter than the margin. But it was 

 now quite different from Gledhill's oval of twenty-one 

 years earlier, the dark margin being broad and dense 

 and the white interior small. The following year it was 

 very faint — the preceding end especially so — and the 

 neighbouring belt interfered with its southern border. 



We have therefore had the great red spot with us for 

 certainly seventeen and a half years ; and it is probable 

 that it existed, but in a less conspicuous form than in 

 1878, for quite nine years before. During this time its 

 colour and its distinctness have altered much, but its size 

 and shape little. 



That a marking of area fully equal to three-fourths that 

 of the surface of the entire earth should continue practically 

 unchanged in size or shape for seventeen years on such a 



