Proctor 1 1 Astronomical Lectures. 



13 



of fhls lot tin tatas New-York. You know the 

 pole is ruiBou about 41. degrees. In Spring the sun rises to 

 a bight or about 60 degrees above the horizon, in Summer 

 33 degrees higher, iii Winter it rises 23 decrees lower afc 

 midday. Suppose instead of 23 decrees tUe change 

 amounted to 60 degrees. Then you would have 

 at the New- York of Venus you would have it 60 

 degrees higher in Summer, which would carry it 10 de- 

 grees north of the point overhead. Tlie sun is circling 

 about the pole, round and round. There would be day all 

 the time, and then there would be tnat tremendous sun, 

 with all the effect of tropical sunshine. Tlie accumulation 

 of heat in the Summer by Venus must be enormously 

 preat. Copsider the Winter. There is the sun in the Spring 

 60 degrees above the horizon, but in Winter itis 50 degrees 

 below. It does not rise at all above the horizon. It is 

 continual merht, and that after that extremely heated 

 Summer. Those changes are not agreeable to our ideas 

 of the possibilities of life. They sugarest the necessity 

 migration. That is absolutely necessary to certain 

 classes of beings here on this earth. Now, human 

 beings on the earth do not migrate, but the 

 inhabitants of Venus, if there are any, must migrate so 

 as always to bo in parts where the sun does not rise 

 too high. That would be quite possible ; it may be '.a 

 absolute essential condition there, not for a portion of 

 living beincs as here, but for all. 



RELATIONS OF THE MOON TO THE EARTH. 



I shall only pause to spe.ik of tho earth in relation to 

 the moon. Our earth has a companion, the moon. We 

 looK upon it as a mere satellit3, but it is another member 

 of the inner family of planets. If you were a member 

 of a world circling around some distant star, you would 

 be unable to distinguish the motion of the moon from 

 that of the earth. It is only from our earrh that it 

 seems to go around us. It really goes around the sun. 

 Every world must have that peculiarity, that it m ist 

 eeein to its inhabitants to be the center of the whole 

 universe. In Venus. Mars, in even the asteroids, each 

 seems to bo the center of the universe. Thus the astron- 

 omers of oil time fell into the mistake of thinking the 

 earth was the fixed center of the universe. 



Mars, instead of being like Venus, is a planet that we 

 can study very fully indeed. We have here the orbits; 

 here is that of the earth, there that of Mars. A portion 

 of the time the face of Mars is turned toward the sun 

 and is also turned toward the earrh, and thus illumi- 

 nated is studied to great advantage. You can conceive 

 therefore how it is that astronomers have been able to 

 take siu;h pictures as these of the planet, having fea- 

 tures resembling those of the earth. There is an appear- 

 ance of two bright white points at opposite sides, which 

 have always been called the snowy poles of Mars. Her- 

 schel was the first to perceive that they waxed and 

 waned in siz 1 . He noticed that the axis was inclined 

 very much like that of our earth, or rather more than our 

 earth, but so nearly like, it tnat the same sort of seasons 

 prevail. He noticed that when the Summer was in pro- 

 gress the polar regions seemed smaller than in Winter. 

 ' lhat was the first thing to show that the planet was 

 like our earth. Our snowy regions do not cover more 

 than the arctic regiona, and they occupy about the 



same proportions as those of Mnr.s's surface. Slncn th 

 polar snows do not extend further, therefore the same 

 sort of climate it seemed probable prevailed there. 

 Other features corresponding to the idea of the bab 

 liability of Mars were noticed. Some portions have a 

 greenish hue, as though there were oceans. The plan- 

 et's continents, or what we call continents, wero ruddy; 

 and white surfaces sometimes seemed to form over these 

 continents or oceans, and to melt away during the day, 



as if clouds were being dissipated by the action of tho 

 sun. 



THE VEGETATION OF MARS. 



There were others, French astronomars, who sug- 

 gested that the vegetation in Mars, instead of green, 

 may be red. Spring may, indeed, come there, blushing 

 like a maid. It was said, however, that we have 

 no evidence that that ia the case. How do we know 

 that these green regions are oceans, or the white regions 

 snow? It seemed somewhat bold to say so to say 

 that that must be the case. Might not the whito 

 region be frozen carbonic acid, and tho ocean 

 something altogether different from what we have on. 

 earth? That argument is put forward by Dr. 

 Whewell, and it seemed very difficult; to overcome 

 it. A man might certainly be thought very bold, 

 on considering that he never could come nearer to Mars 

 than 30,003,000 miles, to say what its surface contains. 

 But we know now as certainly as though we had takea 

 water from it and had It analyzed by a chemist, or 

 drank it; we know certainly that water exists there. 

 The spectroscope comes in here. When the sun is not 

 hieh above the horizon you recogniza in its spectrum a 

 number of sharply defined dark lines. As his liirht 

 shines through the vapors of our atmosphere, the physi- 

 cists caine to know that these Hues were due to water in 

 our atmosphere. Here I take the opportunity to cor- 

 rect an injustice, of which I have been guilty to 

 one of your leading physicists. Dr. Cook of Cambridge. 

 I have been saying in my lectures tha* Sscchi anl 

 Jansen found out that these streaks were due to water; 

 but that fact had been shown in a much more sciontifio 

 manner several months before by your countryman. 

 He observed the sun, noted these bauds as they firs! 

 faintly maile their appearance, while the sun was still 

 high up. Then he took his hygrometer, and he noted 

 that as the hygrometer showed greater moisture in tha 

 air, these bauds became more distinct. He showed be- 

 yond the possibility of doubt that they were due to 

 water In our atmosphere. Mars was observed in 1361 by 

 Dr. Huggins, and it was noticed that across the faint 

 solar spectrum of the planot. there were those wa'er 

 bands. They might have been in the atmosphere of the 

 planet, or they might have been caused ;by the 

 moisture of our own air. But Dr. HuL'gins determined 

 lo remove all doubt by turning his spectrum to the 

 moon, which was low down ; so if the bands of the spec- 

 trum had been due to moisture in our air, they would 

 have been more clearly s?en in the spectrum of the 

 moon's light, but instead of that they were wanting. 

 Therefore no doubt remained that they really belonged 

 to the planet Mars, that there was vapor of water in the 

 atmosphere of tne planet. This was a moat charming 



