[16] Professor Rigaud is of opinion that Galileo had discovered the solar spots at an earlier period than eighteen months before May 1612. Previous to the invention of the telescope, spots had been more than once seen on the sun's disc with the unassisted eye. But even if these were of the same character as those which Galileo and others observed, we cannot consider them as anticipations of their discovery by the telescope. As the telescope was now in the possession of several astronomers, Galileo began to have many rivals in discovery; but notwithstanding the claims of Harriot, Fabricius, and Scheiner, it is now placed beyond the reach of doubt that he was the first discoverer of the solar spots. From the communication which I received in 1822 from the late Dr Robertson, of Oxford,[17] it appeared that Thomas Harriot had observed the solar spots on the 8th of December 1610; but his manuscripts, in Lord Egremont's possession,[18] incontestably prove that his regular observations on the spots did not commence till December 1, 1611, although he had seen the spots at the date above mentioned, and that they were continued till the 18th of January 1613. The observations which he has recorded are 199 in number, and the accounts of them are accompanied with rough drawings representing the number, position, and magnitude of the spots.[19] In the observation of Harriot, made on the 8th December 1610, before he knew of Galileo's discovery, he saw three spots on the sun, which he has represented in a diagram. The sun was then 7 deg. or 8 deg. high, and there was a frost and a mist, which no doubt acted as a darkening glass. Harriot does not apply the name of spots to what he noticed in this observation, and he does not enumerate it among the 199 observations above mentioned. Professor Rigaud[20] considers it "a misapplication of terms to call such an observation a discovery;" but, with all the respect which we feel for the candour of this remark, we are disposed to confer on Harriot the merit of an original discoverer of the spots on the sun. [17] See page 40. [18] These interesting MSS. I have had the good fortune of seeing in the possession of my much valued friend, the late Professor Rigaud of Oxford. [19] Edin. Phil. Journ. 1822, vol. vi. p. 317. See Rigaud's Life of Bradley, Supplement, p. 31. [20] Id. It., p. 37, 38. Another candidate for the honour of discovering the spots of the sun, was John Fabricius, who undoubtedly saw them previous to June 1611. The dedication of the work[21] in which he has recorded his observation, bears the date of the 13th of June 1611; and it is obvious, from the work itself, that he had seen the spots about the end of the year 1610; but as there is no proof that he saw them before October, we are compelled to assign the priority of the discovery to the Italian astronomer.