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86 together by the impact of the incoming matter as well as by its slowly increasing gravitative force. But when it had attained to within perhaps 100, perhaps 50 miles, or less, of its present diameter, a great change occurred in the opportunity for further growth. Some large and dense swarm of meteorites, perhaps containing a number of bodies of the size of the asteroids, came within the range of the sun's attraction and were drawn by it into an orbit which crossed that of Mars at such a small angle that the planet was able at each revolution to capture a considerable number of them. The result might then be that, as in the case of the earth, the continuous inpour of the fresh matter first heated, and later on liquefied the greater part of it as well perhaps as a thin layer of the planet's original surface; so that when in due course the whole of the meteor-swarm had been captured, Mars had acquired its present mass, but would consist of an intensely heated, and either liquid or plastic thin outer shell resting upon a cold and solid interior.

The size and position of the two recently discovered satellites of Mars, which are believed to be not more than ten miles in diameter, the more remote revolving around its primary very little slower than the planet rotates, while the nearer one, which is considerably less distant from the planet's surface than its own antipodes and revolves around it more than three times during the Martian day,