June, 1903.] 



KNOWLEDGE 



131 



aijpeared at the east limb in latitude 18'^ N., and was 

 followed three days later by another, H, in the same lati- 

 tude. On April 30th, when the photograph was taken 

 which forms our plate, and which we owe to the kind 

 permission of the Astronomer Eoyal, these thtee groups 

 were all fully displayed near the centre of the disc. The 



Group G, 1903, April 30. 



two northern groups, G and H, were both streams of sun- 

 spots, the larger of which, G, — first seen on the limb on April 

 •24th — now stretched out to a total length of over 100,000 

 miles. Usually in a stream of sunspots the leading spot is 

 the best defined, and, if not the largest in the group, is only 

 surpassed by the rear spot. If the stream, as is not 

 uncommon, spreads out into two or three branches, 

 inclined to one another at a small angle, they nearly 

 always radiate from the leading spot. In the present 

 instance the reverse is the case. 



It is a curious circumstance, well worth attention, that 

 all these eight groups took their rise in the hemisphere 

 remote from the earth. All were first seen as the rotation 

 of the sini lirought them into view at the east limb. Group 

 B had, alone of the eight, been seen during an earlier 

 rotation, but like the others it formed in the unseen 

 hemisphere and came into view at t)ie east limb, wliere it 

 was first seen, a regular spot, on February 23. 



cttcts. 



[The Editors do not hold themselves responsible for the opinions 

 or statements of correspondents.] 



MAN'S PLACE IN THE UNIVERSE. 



TO TUE EDITORS OF KNOWLEDGE. 



Sirs, — Dr. Wallace's conclusion is a very old one, almost 

 obsolete. The Earth and man are in his view the centre, 

 the end, and the su]iremc pur|iose of the whole iiniverse, 

 aiul everv world and star are in existence for the production 

 and the dcvelopnient of the living soul of man. 



This theory, tliat of all antiqvie religious, has seemed so 

 completely overthrown by the discoveries of science that 

 nobody has dared to defend it. Is the new astronomy 

 coming back after a long digression to the sujireme con- 

 clusion of the ancient learning ': Is the universe a ]>urely 

 anthropocentric thing? AVe do not believe it, and witliout 

 I'ollowini;- our author to theological ground (we are veiv 



incompetent for that) we hope to present some arguments 

 against the views he so firmly advances. 



In the first place, from that strictly scientific point of 

 view which is ours, is it correct to say that the Earth is, in 

 the solar system, a planet peculiar in its habitability ? To 

 discuss that fully, it would be necessary to expound at 

 length the doctrine of the plurality of inhabited worlds, a 

 doctrine well known by the works of Flammarion, Gore, 

 and manv other gifted autl^i- We prefer to rest on the 

 grounds ndopt, I IIa 1 >r. Wallace, anj to admit with him 

 that for sii-uuiini- In. v.c ou^ht ^.t,iKay life such as we 

 know iinj^'Caithj som.; clcui.^,t-^ sitljfciitauces are requisite, 

 and also a temp.^nitiua. Rest^-ainWl between narrow limits 

 during the» hms4 seiiiK'Hi-e of ilji^iages necessary for the 

 evolutioMitJ^liVin- l'<'in^;^ti(i 



A(5W-i1in!» to Di-.v^fcftlace, the conditions of hfe are :— 



1st.— A J^alice" from the Sun sufficient, and just 

 sufficient, to' produce clouds, rains, and river-circulation, 

 and to keep up tbe temperature required. We are of the 

 same opinion, but it seems to us that such a circulation 

 and such a temperature are possible on other planets than 

 the Earth. The spectroscope reveals unmistakable aqueous 

 vapour in the atmospheres of at least Venus and Jupiter. 

 In the general plan of the solar system, the distance from 

 the Sun to the Earth is not peculiar or extraordinary in 

 auv way. 



2ii,i _L^ sufficient atmosphere to produce the said water- 

 circulation, and to equalise the burning heat of the days 

 and the frozen coldness of the nights. Is this equalisation 

 a property exclusively given to our orb? Are the 

 atmospheres of Venus" and Jupiter defective for that 

 office? Dr. Wallace writes also: "The mass of an 

 atmosphere depends largely upon the mass of the planet ; 

 Mars is, therefore, unsuitable for life." Is not this in 

 every way a purely gratuitous assumption ? 



3rd. — A large proportion of the planetary surface 

 covered by oceans, with currents and tides. Tidal action 

 being dependent upon the Moon, the want of such ;< 

 satellite prevents Venus from having high forms of life. 

 The author forgets that the Sun is able to produce very 

 appreciable tides by itself, especially in the case of Venus, 

 to which it is nearer than to our Earth. And on our 

 Earth, to look at the question from another side, tideless 

 seas (as the Mediterranean Sea) are by no means lifeless. 



4th.— The depth of oceans, indicating the permanency 

 of their features. We grant it, but u])on what grounds 

 can we assert that such a depth is wanting on other 

 planets ? 



5th. — The existence of atmospheric dust, produced by 

 deserts and volcanoes, as this is the first cause of rain and 

 clouds. Granted, but volcanoes can exist on other worlds. 

 From this point of view the Moon would be an ideal orb. 

 It is a very curious way of proving that life exists only 

 upon our Eartli to say that d.'serts are peculiar to it. For 

 if there are no deserts on other planets there must be 

 their opposites, viz., a luxuriant vegetation and innumer- 

 able forms of life. Anyway, shooting stars and meteorites 

 might supply quite sufficient dust to produce water- 

 condensation. 



Such are the arguments by which Mr. Wallace sustains 

 his idea that the conditions of life do not co-exist on other 

 planets than our Earth. We believe very firmly that they 

 are absolutely insufficient for any scientist. We believe, 

 on the contrarv, from an impartial study of all the 

 scientific data, that life is possible on other worlds, and 

 that the Earth has not the privilege of being the \mique 

 inhabited and inhabitable orb. 



We arc also unable to accept another view of Dr. 

 Wallace, namely, that on the confines of the universe 

 (supposing it finite) the law of gravitation is not obeyed. 



