changed the course of one of two small bodies as to make them

collide. This seems to me the most plausible theory. Over a

hundred years ago the English astronomer, Chambers, wrote of

having found traces of atmosphere in some of these minor planets,

but it was generally thought he was mistaken. One reason we know

so little about this great swarm of minor planets is, that till

recently none of them showed a disk to the telescope. Inasmuch

as only their light was visible, they were indistinguishable from