Page:The Solar System - Six Lectures - Lowell.djvu/71



In fundamentals, indeed, Mars shows a general similarity to the Earth; but in subsequent characteristics it betrays a most interesting dissimilarity. It is the dissimilarity that modern study has specially brought out.

The cause of the dissimilarity springs from the planet's size. The less mass of Mars did not permit it initially to present so fertile a field for development. Mere size entirely alters physical possibilities. In the next place, its dwarfing caused it to age quicker than the Earth.

Our knowledge of the planets, and especially of Mars, has advanced greatly within the last quarter of a century. The first steps of this advance we owe, not to instruments, but to the genius of one man, the Italian astronomer Schiaparelli. In 1877 he began to observe Mars, and at once showed a keenness of vision surpassing that of any previous observer and a susceptibility to impressions surpassing even his acuteness of sight. It was not so much a matter of eye as of brain. For it turns out now, after the fact, that several of his phenomena had been dimly seen and recorded before, but without that understanding which made of them stepping-stones to further results.

His object was to map the planet