Arago estimated that the comets belonging to the solar system, within
the orbit of Neptune, numbered _seventeen million five hundred
thousand!_

Lambert regards _five hundred millions_ as a very moderate
estimate![1]

[1. Guillemin, "The Heavens," p. 251.]

{p. 83}

And this does not include the monstrous fiery wanderers who may come
to visit us, bringing their relations

###

ORBITS OF THE PERIODIC COMETS.

along, from outside the solar system--a sort of celestial immigrants
whom no anti-Chinese legislation can keep away.

Says Guillemin:

"Leaving mere re-appearances out of the question, _new comets are
constantly found to arrive from the depths of space_, describing
around the sun orbits which testify to the attractive power of that
radiant body; and, for the

{p. 84}