Much of the material was like slag from a furnace,having evidently been partly fused.Whether this heat was the result of collision or of its near approach to the sun at perihelion,they could not tell,though the latter explanation seemed most simple and probable.When at about the centre of the nucleus they were in semi-darkness--not twilight,for any ray that succeeded in penetrating was dazzlingly brilliant,and the shadows,their own included,were inky black.As they approached the farther side and the sunlight decreased,they found that a diffused luminosity pervaded everything.It was sufficiently bright to enable them to see the dark side of the meteoric masses,and,on emerging from the nucleus in total darkness,they found the shadow stretching thousands of miles before them into space.
"I now understand,"said Bearwarden,"why stars of the sixth and seventh magnitude can be seen through thousands of miles of a comet's tail.It is simply because there is nothing in it.The reason ANY stars are obscured is because the light in the tail,however faint,is brighter than they,and that light is all that the caudal appendage consists of,though what produces it Iconfess I am unable to explain.I also see why the tail always stretches away from the sun,because near by it is overwhelmed by the more powerful light;in fact,I suspect it is principally in the comet's shadow that the tail is visible.It is strange that no one ever thought of that before,or that any one feared the earth's passing through the tail of a comet.It is obvious to me now that if there were any material substance,any gas,however rarefied,in this hairlike[1]accompaniment,it would immediately fall to the comparatively heavy head,and surround that as a centre."[1]Comet means literally a hair.
"How,then,"asked Cortlandt,"do you account for the spaces between those stones?However slight gravitation might be between some of the grains,if it existed at all,or was unopposed by some other force,with sufficient time--and they have eternity--every comet would come together like a planet into one solid mass.Perhaps some similar force maintains gases in the distended tail,though I know of no such,or even any analogous manifestation on earth.If the law on which we have been brought up,that 'every atom in the universe attracts every other atom,'were without exceptions or modifications,that comet could not continue to exist in its present form.Until we get some additional illustration,however,we shall be short of data with which to formulate any iconoclastic hypothesis.The source of the light,I must admit,also puzzles me greatly.There is certainly no heat to which we can attribute it."Having gone beyond the fragments,they applied a strong repulsion charge to the comet,creating thereby a perfect whirlpool among its particles,and quickly left it.Half an hour later they again shut off the current,as the Callisto's speed was sufficient.
For some time they had been in the belt of asteroids,but as yet they had seen none near.The morning following their experience with the comet,however,they went to their observatory after breakfast as usual,and,on pointing their glasses forward,espied a comparatively large body before them,a little to their right.
"That must be Pallas,"said Cortlandt,scrutinizing it closely.
"It was discovered by Olbers,in 1802,and was the second asteroid found,Ceres having been the first,in 1801.It has a diameter of about three hundred miles,being one of the largest of these small planets.The most wonderful thing about it is the inclination of its orbit--thirty-five degrees--to the plane of the ecliptic;which means that at each revolution in its orbit,it swings that much above and below the imaginary plane cutting the sun at its equator,from which the earth and other larger planets vary but little.This no doubt is due to the near approach and disturbing attraction of some large comet,or else it was flung above or below the ordinary plane in the catastrophe that we think befell the large planet that doubtless formerly existed where we now find this swarm.You can see that its path makes a considerable angle to the plane of the ecliptic,and that it is now about crossing the line."It soon presented the phase of a half moon,but the waviness of the straight line,as in the case of Venus and Mercury,showed that the size of the mountains must be tremendous compared with the mass of the body,some of them being obviously fifteen miles high.The intense blackness of the shadows,as on the moon,convinced them there was no trace of atmosphere.
"There being no air,"said Cortlandt,"it is safe to assume there is no water,which helps to account for the great inequalities on the body's surface,since the mountains will seem higher when surrounded by dry ocean-bottom than they would if water came halfway up their sides.Undoubtedly,however,the main cause of their height is the slight effect of gravitation on an asteroid,and the fact that the shrinking of the interior,and consequent folding of the crust in ridges,may have continued for a time after there was no longer water on the surface to cut them down.
