Page:Popular Science Monthly Volume 51.djvu/698

682 thirteenth century the great Encyclopædia of Matouan-lin contains forty-five mentions of the phenomenon. The existence of dark spots on the sun was recognized very anciently by the aborigines of Peru. The Arabs have recorded prolonged observations of the disk of the sun, among which are those of 535 and 626.

The oldest mention of a sun spot in Europe, a spot which was supposed to be Mercury, is by an anonymous chronicler of the eighth century. Different observations of sun spots before the invention of the telescope are recorded in Zach's Monatliche Correspondenz, vol. xv, 1807, and in Humboldt's Cosmos, vol. iii.

The new instrument, invented in Holland, first permitted the scientific study of the solar surface. Galileo appears to have seen the spots on the sun for the first time in October, 1610, but did not account for the nature of the phenomenon. Jean Fabricius may have remarked the spots toward the end of the year 1610, and certainly observed them in March, 1611. Scheiner reported his discovery of the spots in April, 1611, but did not account for what he saw. Harriott, who is believed by Zach to have seen the spots as early as December, 1610, and whose manuscripts have been examined by Rigaud, did not really see them till early in December, 1611, and comes, consequently, only fourth in the order of priority.

There have been lively controversies at different times concerning the claims of these three astronomers to priority in the discovery of the sun spots. The discussions were summarized by Arago in an article published in l'Annuaire du Bureau des Longitudes in 1842. The question has been settled by deciding that Galileo first saw the spots with the aid of the telescope, but that Fabricius first announced their existence to the scientific world and pointed out their nature. The texts were plain enough on this point, and the discussion was prolonged more by the agitation of questions concerning the meaning of words than by any need of clearing up the facts.

A work recently published by Dr. Gerhard Berthold on Fabricius contains a number of previously unpublished documents, and throws light on some obscure points in the history of astronomy at the beginning of the seventeenth century.

An interesting analysis of this essay has been published by M. E. Millosevich in the Atti of the Accademia dei Lincei of Rome. While its main object is to establish the claim of Jean Fabricius to priority in the discovery of the sun spots, it further furnishes many facts previously unknown in the life of this astronomer and