444 



♦ KNOWLEDGE ♦ 



[Mat 22, 1885. 



Now, it is said (siijira) " The vapour of water is present in [his] 

 atmosphere — clouds form there ; snow falls, and perhaps rain, from 

 time to time." 



It is reasonable to suppose that if Mars has had a past exist- 

 ence like ours, he has ]iroduced a head-race not unlike men. I 

 suppose our globe grown so cold that rain never falls at all any- 

 where, even then, I think it would be long before we should be 

 extinguished. We are all — wise and unwise — much too apt to 

 infer the impossible from the undone. Mr. W. M. Williams would 

 not admit that I had shown men could probably live naked in cold 

 climates, as C;caar says the Britains did. Mr. C. Duncombe (1657) 

 quotes Darwin as reporting how the Fuegians actually do so. 

 We would build immense Cryst.al Palaces, live in them always, 

 only going out for exercise, commerce, and the chase. We should 

 ripen crops under glass, grow vegetables, and fatten cattle under 

 it too. Perhaps ice might prove a most superior substitute for 

 stone ; it would let in light and heat-rays, at all events. In the 

 north of Europe many families never leave their habitations all the 

 winter. Beneath the ice on sea, lake, and river, there would still 

 be tish ; these we should catch by breaking the ice. Plenty of 

 animals would still be found wild, aa they now are in [the Arctic 

 regions. 



if all this^ might be, a fortiori is it better in Mars. Vapour 

 of water surely proves that his seas are not all frozen ; how could 

 it get into the air without water, and a sun hot enough to vaporise 

 that water. Nay, the extensive melting of the polar snows in 

 Mars'a summer surely shows that his climate is, on the whole, 

 hotter*than our own. I very much question whether any tele- 

 scope planted in Mars would show, on the earth, any diminution at 

 all iu the same regions, same season. His summer being twice as 

 long will, however, give his sun an advantage. 



The unique colour of Mars may probably explain this. We aro 

 justified in saying that it does not arise from red land or red seas, 

 because we find by the spectroscope no substances, save helium, 

 unknown on earth ; hence his land and water must be pretty much 

 like our own. There remains only the air, and the gas mixed 

 therein, which produces the redness of the orb, may be far more 

 heat-conserving than the water which is so rare thereon. It has 

 been shown that water is blue, though we never should have 

 guessed it (a tube of distilled water 10 ft. long when looked 

 through is a beautiful azure), and this surely explains why we 

 enjoy a blue sky. No doubt we look blue to Mars. He has little 

 water in his air, therefore he is not blue ; but to make him so very 

 red there must be ^ouicthing — not, indeed, unknown here, but 

 whose colour is unknown, as was, till very lately, that of water. It 

 may be oxygen, since this gives redness to the blood. If Mars has 

 a large quantity of it in his air, heat and life must be conserved far 

 more than here. 



2. " The once teeming surface of our companion planet." 



I do not believe tlie moon ever has been inhabited, for the fol- 

 lowing reasons : — 



(a) She is without the conditions — air and -water. Now, we have 

 no example before us of a globe ever having lost these. All the 

 globes we have examined have them — or the first of them, at least. 

 It is impossible that all the lunar seas can have retreated inside, as 

 some say, because, this implying extreme old ago, the concomitant 

 cold would freeze a notable part of them before all had percolated 

 away ; this part would be vaporised by the fierce fortnight of the 

 lunar day, and become visible to us as clouds. These, of course, 

 would require air to float in ; if there ever was air, where is it ? 

 The cold of space might freeze it certainly, in the long night ; but 

 the day would vaporise it again. 



(b) If there ever had been rain on the moon, there would bo 

 rivers ; but there are none. Imagine our globe deprived of air and 

 water. Nothing would be more conspicuous from the moon, in a 

 good telescope, than the beds of the Thames or the Loire ; still 

 more the Amazon. A river tapers and meanders, by its nature 

 and her tributaries. There is nothing of the kind in the moon. 



(c) As in Mars, there would probably have been quasi-human 

 creatures in the moon. But there is no reason to think there ever 

 had been, because there are no traces of human work. Imagine 

 the earth frozen to death, and deprived of air and water; from the 

 moon, with our best telescopes, we should see objects 100 ft. long. The 

 Pyramids, all cities, especially fortress cities, would be distinctly 

 visible to us. Paris, at sunset or sunrise, would be a beautiful 

 polygon, in which we could see Notre Dame as a cross-shaped 

 building. Were we on the moon note, we could watch each ship on 

 the sea — publish gazettes of all terrestrial battles. There is no 

 regular work discernible on the moon; ergo, &c. 



(d) The lunar rilles are unlike anything we see on earth. Possi- 

 bly we have rilles, too, but covered by erosion. Were that so, their 

 visibility on the moon would show that she has never undergone 

 that process of denudation which has created our corn-producing 

 surface. 



It may be urged very justly that it is most unlikely there would be 

 a uni(iue globe, never the scene of life. Yes, if the moon sprang 

 off the earth, or the sun. But is it improbable that she was once 

 an independent, errant body, which chanced to pass us near enough 

 to stay for ever ? The Arcadians boasted that their fathers were 

 •7rpotytKt]voi — had dwelt there before there was a moon. This very 

 extraordinary tradition has been explained by supposing they mis- 

 took the original word, which may have been Trpof XXt^vec — i-^-t before 

 the Hellcnoi. But there is nothing to prove that the lost initial of 

 EXXi;v was " a," and why should the other differences have arisen ? 

 This suggestion (of the extraneous origin of the moon) is, of course, 

 an extravagant paradox. It has this, however, in its favour. The 

 moon is the only companion planet in the system. Now, it is 

 improbable {vt svpra) that there should be a vnique globe. (Which 

 Saturn can hardly be called, because his rings are but discrete 

 satellites, and will some day fall on his globe, according to present 

 observation.) Hallyakds. 



THE EVOLUTION OF THE SENSE OF BEAUTY. 



[1713] — "S. H." (1700) somewhat misconcoives my purpose. 

 The question I have tried to answer is nnt, " How did the coloui-- 

 sense first arise?" but, "Granted the colour-sense, how did its 

 exercise come to be pleasurable f " However, if we shift the 

 difficulty a step, and, instead of assuming an inchoate sensibihty to 

 colour, merely assume that sensibility to light which exists in very 

 low forms of life, we may conjecture that light-waves of different 

 lengths would tend to affect the organism differently, and that 

 there would be a corresponding difference in the resulting sensa- 

 tions. At the present stage of our knowledge, it seems impossible 

 to frame even a plausible hypothesis of the evolution of the organs 

 of sense ; and (assuming the truth of the Young-IIelmholtz theory), 

 I do not pretend to " explain " how the nerve-endings were 

 differentiated for the reception of special kinds of light. 



Constance C. W. Naden. 



CONCEPTIONS AND IMAGES. 



[1714] — " J. S." (1702) cannot possibly know that the inde- 

 pendent " something " which causes his sensations in any way 

 resembles the sensations themselves. His "conception" is of the 

 grouped sensations, not of anything " external." C. N. 



MATTER REQUIRING REFLECTION. 



[1715]—" M. T. H." (letter 1701) does not puzzle me at all. At 

 the moment I am writing, I have opposite to me a looking-glass 

 above a mantelshelf, on which are three glass vases. I am looking 

 at them from the right side ; they are reflected in the glass all to 

 the right of each vase, but at exactly the same distance from each 

 other in the glass as they appear from each other on the mantel- 

 piece. Now I go to the left. The reflections appear on the left 

 side now, but the distances from each other in the glass and on the 

 shelf are even then the same exactly. Hence it appears that not 

 the reflection in the glass has changed its position, but I know my 

 position or relation to it has changed. Each vase is reflected true 

 in the glass, i.e., exactly half-way round. If I look from the right 1 

 see only the portion reflected to the right ; if I look from the left, 

 only the portion reflected to the left side of the vase ; if I look 

 straight in front, I see the front half only of my vase, only because 

 it hides the back or reflected half. If I get up and look over my 

 vase I see the true and full reflection in the glass, which common 

 sense tells me must be there, whether I or anybody sees it or not. 

 F. W. H. 



[171G]— Perhaps it will help " M. T. H." (letter 1701) to under- 

 stand his mirror, if he considers the following similar case : — 



" If I stand in one part of my room, I see the sun through one 

 pane of the window ; if I move to another part, I see it through 

 another pane ; if two persons stand in the room, they see it through 

 two different panes. Which pane does the sun shine through when 

 no one is in the room, or does it shine at all ? " 



Of course, the answer is, that the sun shines through all the 

 panes, but is only seen through that one whicb is in a line with the 

 sun and the eye, and that his clock is reflected in every part of the 

 mirror, but is only seen in that part which reflects the light from 

 the clock to the place where ho is standing. 



Howard Grahamf. 



SKY AND WEATHER. 



[1717] — May 8 (Pornic, Loii'e Infcrieure),as the sun was setting, 

 I noticed a rare white brilliancy around him, as after sunset in the 

 days of the ofter-glow. Up to 11 at night there was a brilliant 



