Page:The story of the comets.djvu/80



"How does a new comet become known?" "Who looks out for comets?" "Who organises observations of comets?" These are questions which are often asked, and which are seldom answered in set terms in the text-books; and therefore it may be worth while to devote a short chapter to the subject.

In early times and down to the invention of the telescope and for quite a century and a half after that event, the discovery of comets may be said to have been left to chance: in other words they discovered themselves; that is to say, manifested themselves to anybody who happened to be looking at the heavens by night. It was not until 2 French astronomers towards the close of the 18th century took up the matter that any definite effort seems to have been made systematically to watch for or to search for comets. Messier, whose first comet dates from 1760, and Pons, whose first comet dates from 1802, are the 2 Frenchmen here referred to,