326 



NA TURE 



[Feb. 2\, 1878 



gigantic armadilioes which in past geological epochs were 

 so abundant in Southern Brazil, The little Chlamydo- 

 phorus truncatus is, we believe, mainly, if not entirely, 

 subterranean in its habits. May there not still exist a 

 larger representative of the same or nearly allied genus, 

 or, if the suggestion be not too bold, even a last descendant 

 of the Glyptodonts ? 



SUN-SPOTS AND DECLINATION RANGES 



THE excellent article by Mr, Broun in a recent number 

 of Nature puts before us in a very clear manner 

 the strong grounds that we have for believing in a true 

 connection between sun-spots and terrestrial magnetism. 

 If the argument Avere not already sufficiently powerful it 

 might be yet further strengthened by bearing in mind 

 that not merely do the most prominent inequalities march 

 together in these two phenomena but the correspondence 

 extends likewise to those waves of shorter period that ride 

 as it were on the back of the longer ones. In a paper 

 which is now before the Royal Society I have shown this 

 intimacy of correspondence by comparing together the 

 sun-spot and declination range records for the cycle 

 extending from the minimum of 1855 to that of 1867, All 

 the prominent sun-spot waves are reproduced by magnetic 

 declination waves, the latter, however, invariably lagging 

 behind the former. 



Then with regard to the long period cycle under discus- 

 sion I make it to begin for sun-spots with September 1 5, 

 1855, which was a minimum point, and to end with 

 March 15, 1867, which was another minimum point. On 

 the other hand the corresponding cycle for declination 

 range begins with February 15, 1856, and ends with 

 August 15, 1867, Thus the length of period is the same 

 in both ; the magnetic cycle lagging, however, five months 

 behind that for sun-spots. 



I may also mention that I am at present comparing 

 together the Prague declination ranges with the sun-spot 

 curve determined from Hofrath Schwabe's observations, 

 and although the comparison is not finished, I believe 

 that this lagging behind will form a prominent feature of 

 the results. Further back than Schwabe we cannot go, 

 as the sun-spot records are not sufficiently accurate for 

 this kind of work. 



I am not sure, however, that I quite agree with Mr. 

 Broun when he says "no doubt the admission of the 

 existence of a causal connection between the two phe- 

 nomena is opposed to the hypothesis, which many other 

 facts render wholly untenable, that the magnetic variations 

 are due to the heating action of the sun." 



As far as sun-spots and declination ranges are concerned, 

 what are the facts regarding the connection between them ? 

 These are two in number. In the first place, all the 

 considerable oscillations of the sun-spots are reproduced 

 in the declination-ranges. Secondly, the reproductions in 

 the declination-ranges lag, it appears, behind the cor- 

 responding sun-spot waves. This latter fact strikes me as 

 being rather in favour of the view which regards declina- 

 tion-ranges to be (like temperature-ranges) in some way the 

 result of an influence from the sun which is of the nature of 

 an emanation or radiation. But I will not press the 

 point except to remark that this and a host of other 

 questions, some of them of great importance, must wait 

 for their solution until we shall have obtained a sufficiently 

 complete and continuous record of solar activity, and 

 along with it an equally complete and continuous record 

 of the radiant power of the sun. 



From the observatories already established, we have a 

 reasonable prospect of receiving good magnetical infor- 

 mation,. and there is abundance of meteorological activity, 

 but it is nearly, if not absolutely, impossible, from the 

 observations already made, to tell whether the sun be 

 hotter or colder as a whole, when there are most spots 

 on his surface. The sooner we get to know this the better 

 for our problem. Balfour Stewart 



THE ISLANDS OF ST. PAUL AND 

 AMSTERDAM 



AS is now well known, a French expedition visited 

 these islands towards the close of 1874 for the pur- 

 pose of watching the transit of Venus across the sun on 

 December 9 of that year. M. G, de I'Isle accompanied 

 the expedition as botanist ; Dr. Rochefort, with M, Velain 

 to assist him, were to look after the zoological and geo- 

 logical departments. M. Velain, who was a pupil of Prof. 

 Lacaze-Duthiers has just published, in the Archives de 

 Zoologic Exph'imentale et Generale (tome 6, 1877), a most 

 interesting account of these islands and their fauna, with, 

 in addition, a very detailed account of the collections of 

 shells made. We are indebted to the extreme kindness 

 of M. Velain for the excellent illustrations which accom- 



FiG. I. — Kinepin RocTc. 



pany this notice, which are taken from the original 

 memoir. 



If the reader wishes to fix the exact position of these 

 curious islands he has only to trace along the line of 

 lat. 40° S., and about mid-way in the Southern Ocean 

 between the Cape of Good Hope and Melbourne, near 

 long. 80° E., he will find them. 



Their discovery has been claimed by the Dutch and the 

 Portuguese. Placed just in the grand ocean route foi all 

 vessels leaving the Cape for Australia or China, they were 

 doubtless, despite their isolation, long known. The history 

 of our knowledge of them from 1522 to the present day is 

 well, though briefly, written by M. Velain. 



The Novat-a called at St, Paul in 1857, and stayed for 

 fourteen days, and we are indebted to Hochstetter for an 

 excellent account of the geology of the island, though 



