"O thou, God's mariner, heart of mine, Spread canvas to these airs divine. Spread sail and let thy past life be Forgotten in thy destiny." [1]The action that drives off the material of a comet's tail proves that other forces besides gravitation are operative in the interplanetary space.--_The Sun_, C. A. Young, p. 156. [2]See _Recreations in Astronomy_, p. 357.