Among the myriad of stars scattered through the vault of heave there are none which have so much taxed the imagination of the learned as comets. They have often given rise to the most opposite and most ridiculous hypotheses. Decartes thought they were only old stars which had become crusted over and sick, and which being to feeble to maintain their places, were borne away by the vortices of neighboring stars.

The learned themselves have contributed largely to all the errors circulated by the vulgar about these strange stars, and even astronomers, though least of all, have supplied their contingent. At one time the appearance of comets inspired such dread that people shut themselves up in their dwellings in order not to see their horrible aspect; now-a-days, on the contrary, we rush out of doors the better to gaze upon their luminous tresses. Naturally enough ignorant crowds were alarmed when the most enlightened men, such as J. Bernouilli, maintained that the tail at least, if not the body of the comets might be looked upon as a sign of celestial wrath.