2 Tribune Ertras 



They woulrt rercv*n!ze the process aud u.io it IMC!:, an 1 

 say tlr.it the tire, did not contract from a vegetable mass, 

 but sprung froia a small vegetable mass, aud grew by 

 the addition of matter. 



Then I think there 13 another polut to notice. They 

 raav reject tlie notion formed of the vegetable mass, 

 a:ul say very reasonably, that with all duo respect to 

 the opinion of so highly eminent a May-fly as ho who 

 propounded tlio condensation theory, whole days have 

 passed since they have formed truer ideas. So I think it 

 Is with the theory of Laplace ; w.; have a great respect 

 for him, for ho was the greatest mathematician that 

 ever lived after Newton. But we must consider these 

 Wonderful tacts that wo have recently learned about 

 the planets about the sun's conditions, about the heated 

 condition of Jupiter and Saturu, about the relation of 

 cornets and meteors. We have learned that the earth is 

 growing, though not appreciably; as I have stated to 

 you, the earth increases only one inch in diameter by 

 the fall of meteors 111 400,000,000 years. We can hardly 

 call that growth at all, but still, like the tree after it 

 it has ceased to crow, and only lives, the present de- 

 velopment of the earth shows us, leads us, to look back 

 at the distant past, when the meteor system was more 

 numerous, aud the whole solar system was grow- 

 ing. It seems more natural to look at the process as a 

 process of accretion than of contraction from some neb- 

 ulous mass. 



THE THEORY OF ACCRETION. 



We will now have the room darkened, and this process 

 will be illustrated on the sereeu. With tins new view of 

 the matter, does it promise to give us liglit ou auy ques- 

 tions which, were previously unanswered 1 Will it ex- 

 plain how the planets are arranged in the manner in 

 which they are 1 Wo shall find it will. You have a pic- 

 ture illustrating the great difference in size between 

 the outer part and the inner part of the system. 

 Here are Uranus, Neptune, Saturn, and Jupiter, and 

 here in the lower right-hand corner you will notice a 

 circle only as luriri- as represents the planet Uranus; 

 within it are Mercury, Mars, the Earth aud Moon, and 

 Venus. We. mitrht imagine a great nebulous mass like 

 the lire -mist of llei sehel, iu space, gradually approach- 

 tag towards the sun, approaching spirally. Wo might 

 conceive that as the beginning of all things, like the tree 

 from the seed. We know that as one nebulous mass 

 parses into an ither by condensation, heat and light 

 are produced. 



There is evidence that these nebula* are gaseous. 

 Well, then, these, nebulous masses would bo thrown into 

 the great renter. There would be one center of aggre- 

 gation. That center woulJ grow continually in size and 

 power, gradually draw in more and more matter to it, 

 and the more It drew in of these nebulous masses, the 

 greater its power would become. How then does the 

 secondary aggregation take Its origin I I suppose that 

 would arlso uot iu one direction only, but 

 ome in ono and somo In another, with a 

 superabundance in ouo direction ; great subor- 

 dinate masses would bo formed, perhaps, ' 

 cot continuing i-eparatu for any length of lime. In the 

 neighborhood of a great central aggregation, u cuthur- 



Pampltlet Scr;Vr. 



mg of that kind could not form, for the reason that .> 

 the motions near the great central aggregation would ci, 

 very rapid. Tako our sun, which is the original center of 

 aggregation, aud we flu I that iu the sun's neighborhood 

 the motions are very rapid. A body coming out of 

 space aud falling into the sun would reach the sun at a 

 velocity of 330 miles a second, and if only going around 

 the tun, would travel 290 miles a second, 

 but at the distance of Jupiter the velocity of an arriving 

 object would be only about 12 miles a second; therefore 

 it would be easier for an aggregation to form at that 

 distance, some great distance from the center. It would 

 not have to overcome the tremendous velocities which 

 an aggregation would have to master in attempting to 

 form near the sun; it would have time to catch 

 the flying masses. A secondary aggregation 

 at a considerable distance from the center would not 

 Buffer from this great velocity. Au aggregation 

 there would have gri-ater power over matter around 

 it, and a larger and larger aggregation would form, and 

 as it became larger and larger it would be more and 

 more mighty; by a sort of geometrical progression it 

 would grow larger and larger, while all the objects at- 

 tempting to form within its influence would be kept 

 down, reduced iu size. Thus wo explain the fact that 

 we find Jupiter, the greatest aggregation, at a much 

 greater distance thau the inner family of planets and 

 the asteroids. 



Beyond Jupiter wo come to another system, which 

 shows feigns of greater activity and development. At 

 Saturn's distance the motions would be less rapid than 

 at Jupiter's distance. There would still remain a great 

 quantity of matter out of which an aggregation would 

 be formed, anii so wo should find S tlnrn, uot so lari^o as 

 Jupiter, because tlie matter would naturally decrease 

 outwards from tho suu, but owing to the smaller 

 velocity there would bo a greater freedom of 

 aggregation, trid 60 \vo have Saturn, with a 

 ring around It, and its eight satellites. And 

 then we next coino to Uranus and Neptune, and tliey are 

 smaller, because the quantity of matter diminishes with 

 distance. Then take the inner family, close to the sun. 

 Close Jo the sun, they are prevented from accumulating 

 much by tho suu's neighborhood, because of tho tre- 

 mendous velocity of matter there, and they are 

 consequently small. Passing far out aeain, wo 

 find tho influence of Jupiter beginning to bo 

 felt, Jupitor resisting the formation of an aggregation 

 within bis Influence, The combined influence of Jupitor 

 and Saturn preventing agirregations from forming, re- 

 sults iu tho smallness of Mars; ami close within tho 

 palh of Juiiltcr's influence we find the zone of asteroids, 

 each too small to form a planet. 



That is better than Lipl. ice's thepry. It Is not to bo 

 expected that you could have a complete account ol 

 those relations, neither could you by theory explain tho 

 size and color of every bough and leaf, and the detailj 

 of arrangement of a ireo. 



COMI'LIMENT TO AN AMERICAN ASTRONOMER. 



And now I shall allude to the strantrc results obtained 

 by Prof. Daniel Kirkwood, of Ulooiniugton, In. liana., 

 whom. I have called the Kepler of modern astronomy 



