16 



Tribvne Extras Pamphlet Scrfet. 



clouds which havo sometimes been compared to the 

 trade-wind zones. But our trade-wind zones and banda 

 of clouds upon the equator would not be visible from a 

 distant planet. 



When Jupiter is brought on, you will realize how 

 much Jupiter differs from Mir*. You will feel whoa 

 you look on these views of Jupiter, taken at Cam- 

 bridge Observatory, that you have before you an 

 atmosphere heavily luden with some kind of vapor 

 or vapors, It may be many. Cloud masses traveling 

 over the surface- of lands and seas would show 

 eomo degree of agreement in shape with the con- 

 tinents over which they traveled, and if disturbed 

 by the wind they would be torn apart ; but we find them 

 great masses, ns If their d>'pth corresponded with their 

 breadth, as if the depth of these cloul masses was as great 

 as their length and breadth everything that the tele- 

 ecopo shows us leans to the conclusion that there is a 

 deep atmosphere. 



You have iu the lowest right hand picture a very 

 email round disc of one of the satellites of the planet 

 Jupiter, and the diameter of it is 2.009 miles. Imagine 

 the 20ih part of that tiny satellite; 'hat would be 100 miles. 

 It is Inconceivable that these cloud masses have no 

 greater depth than the 20th part of that little satellite. 

 You must feel that these clouJ masses, as they appear, 

 Lave a depth comparable with their length. 



If the atmosphere of Jupiter were only 100 miles deep, 

 the pressure at the bottom would be so great that the 

 lower atmosphere would boa million of times as dense 

 as platinum, the heaviest of all the elements. It is utterly 

 impossible, of course, that any such atmosphere 

 could exist; but that is (ho legitimate calculation, the 

 pressure would be millions of times as great as ours, so 

 as to produce a density equal to that of platinum. 

 There is one peci/narity about t'ue planot opposed to that 

 Idea. Instead of Jupiter being the deuscsfcplanet, it is less 

 ileus,, than tho eartli It? 'lensity is one-fourth the real 

 density of the earth aim corresponds witn that of tho 

 eun, and this seems to givo an explanation of tho difll- 

 cnlty. The great compression of tho sun's attraction 

 would malcc In- atmosphere dense, but his enormous heat 

 expands the atmosphere, and instead of being a dense 

 globe, wo have a globe less tfense than tho earth. 

 Must it not, be manifestly so in the case of Jupiter, and 

 that by its great size it is brought more nearly in rela- 

 tion to the t-un than to the earth, and must it not be like 

 the sun iu regard to tho heat within his globe 1 You 

 Lave tin; argument derived from the compression of 

 lh>- atmo-pheie of tho planets. Again, tho clouds aro 

 formed ainl earned around and around, and tho planet 

 carried nrouml and around in 10 hours, tho equatorial 

 moro rapidly than the temperate zones. Notice tho 

 equatorial band, brighter than the rest, and you will 

 pereeive that it coiTe-ponds with the equatorial band of 

 tho sun. There ap- no i.-atim'* In Jupiter like those in 

 the earth; and all troes to l>ow a planet more of tho 

 nature of the HUH than like ours. lint misrht not the ap- 

 pearances be those of ordinary eloiid-i, after a-111 



That can be tested by experiment. The light of that 

 planet, instead of giving tho same kind of light as if 

 made of roeky matter and covered with btoncs, sbineg 



three times as brightly: It shines almost as brightly as 

 if in tho midst of a mass of clouds or snow. If Jupiter 

 were purely white, you might say that it was only these 

 clouds shining that we see ; but in point of fact, Jupiter 

 dues not look white. Therefore you have tho certainty 

 almost that there must ba an Inherent light in it, and if 

 it be Inherent light, if the'centerof tho planet elves it 

 out, It must be at a heat corresponding to that oi red- 

 hot Iron. 



The satellites of Jupiter may be bodies well lighted, 

 though not intended to supply light to the planet. All 

 tho satellites cannot supply tho planet with 1-lttth of 

 the light which we get from the full moon. They are 

 illuminated by the small sun of Jupiter, which is but 

 the oue-twenty-fifth part of our sun in size. We will havo 

 another picture of Jupiter. You .see how processes are 

 taking place which seem to have led to tho uprising 

 from some interior surface, perhaps a surface far down 

 below the atmospheric envelope, the uprising of a great 

 cloudy mass, surrounded by u dark border, which was 

 distinctly visible to Prof. Mayt-r for hours. Everything, 

 as I think, seems to show us that iu Jupiter we have a* 

 scene of tremendous activity. 



THE RING STSTEM OF BATtTnV. 



Now to his brother giant, tho planet Saturn, with Ms 

 glorious ring system. Those belts on Saturn correspond 

 iu kind to those that exist on Jupiter; and I might ap- 

 ply the argument on Jupiter to Saturn without any 

 further explanation. This great bolt of Saturn during tho 

 whole long year of Saturn lasting 29 years of ours 

 remains persistently equatorial. Now the axis of 

 Saturn is inclined very much as the earth's axis 

 is inclined, but the equatorial belt never shifts, follow- 

 ing tho sun, as ours does, along the ecliptic. It seeing 

 by its position to show that it is produced by a force re- 

 siding iu tho planet itself. Now there is one argument 

 derived from the ring of Saturn. Tho<e rings havo been 

 described by Browster as glorious bodies reflecting light 

 on Saturn, and making up for want of tiie sun. Instead 

 of doing that, those rings* cut off tho sunshine. 

 You will see how tho rincrs appear when 

 they are seen edgewise. Tho planet Is in tlm full light 

 of tho sun, and tho ring is cutting off every little light 

 indeed, and no harm is done. But tiie planet changee- 

 and tho ring shifts in position backward or forward a3 

 the year proceeds. Look at this picture illustrating 

 those changes, and 3'ou will KOO that where the 

 Winter of part of tho planet Is in progress when 

 more light Is wanted. tho riii? cuts ofl 

 tho light. So If we are to argue from 



