THE PLANET VENUS 535 



on the one and accumulation on the opposite hemisphere must end in 

 taking the whole supply, surface or aerial, from the day side to pile it 

 up in perpetual ice upon the night one. Dry air more or less laden 

 with dust must therefore constitute now the atmospheric covering of 

 the sunward hemisphere. Now this is what gives Venus her excessive 

 luster — an atmosphere devoid of cloud. It is precisely because she is 

 not cloud-covered that her luster is so great. She " clothes herself with 

 light as with a garment" in consequence of a physical fact of some 

 interest. As becomes the Mother of Loves, this drapery is gauze of 

 the most attenuated character, and yet on that very account is a great 

 heightener of effect. For it is a well-known property of matter that a 

 substance when comminuted reflects much more light than when 

 massed as a solid or an opaque cloud. Now an atmosphere is itself such 

 a comminuted affair and especially is made lucent by the dust of one 

 sort and another which it holds in suspension. This would particu- 

 larly be true of Venus for the reasons we have exposed and thus stands 

 explained her albedo of .92 which were she cloud-covered could not 

 exceed .72, the albedo of cloud. This brightening character of an 

 atmosphere stands corroborated by what we perceive of the other planets. 

 Mercury and the moon, which are airless bodies, have an albedo of only 

 .17; Mars, which has some air but not much, one of .27; while Venus, 

 whose sky is clear, one of .92. 



Another phenomenon which has greatly puzzled astronomers stands 

 accounted for by what we have learned latterly of the world of Venus. 

 For years by one observer or another a sort of faint phosphorescent 

 shine has been reported of the unilluminated part of her disk ; the ashen 

 light, it has been called. The side of her which should be dark has 

 appeared ghostly lighted up. The phenomenon has seemed the weirder 

 for the difficulty of explaining it. It is like what dimly reveals the old 

 moon in the new moon's arms. With the moon this is earth-shine ; the 

 moon-shine the earth herself lends her satellite. But Venus has no 

 neighbor to act as mirror near her, though such be her astronomic 

 symbol. The earth is too far off and the stars inadequate to the occa- 

 sion. But the state of things we have sketched furnishes an explana- 

 tion. If the night side of Venus be a vast stretch of polar ice, here is 

 just the surface to reflect the starlight with something approaching a 

 phosphorescent shine. Nor would this necessarily be dimmed by the 

 dust of ages because of a slow process of glacier rejuvenation constantly 

 in progress, due partly to the winds, partly to a slow sinking of the 

 debris to the bottom. 



Such are some of the peculiar phenomena presented by the planet. 

 When we thus reason about them — and even in science reasoning is not 

 so much to be despised as some mechanical souls would have us believe 

 ■ — we see that they lose their oddity, becoming the very pattern and 

 prototype of what we should expect. 



Logical deductions from well-established fact has led us to explana- 



