14) Mr. Drinkwater's Observaliotis respecting 



had observed these stars independently of Galileo, and if in- 

 dependently, perhaps anteriorh^ 



If it be thought that I have put a meaning on this passage 

 which it was not intended to bear, some excuse may still be 

 found in the fact, that whether or not Borel intended to lay the 

 foundation of a future claim, this end, which as I contend he 

 had in view, has actually been attained. In the Encyclopedia 

 Britatniica, under the article 'Optics,' the following remark 

 occurs, after the substance of Borel's account has been stated : 

 " Thii, it is jii'obable, was thejirst observation of Jupiter's satel- 

 lites, though the person who made it was not aware of the im- 

 portance of his discovery." In Dr. Young's Lectures on Natu- 

 ral Philosophy, the same idea has resulted from the perusal of 

 this passage. Dr. Young says: " The first person, who is cer- 

 tainlv known to have made a telescope, is Jansen, aDutchman; 

 — and one of his family discovered a satellite of Jupiter with them. 

 Galileo had heard of the instrument, but hat! not been informed 

 of the particulars of its construction : he reinvented it in 1609, 

 and the following year rediscovered also the satellite which Jan- 

 sen had seen a little before." It cannot therefore be doubted 

 that owing to the manner in which Borel has introduced this 

 account, John, the son of Zachary Jansen, has had the ciedit 

 of the discovery given to him : it cannot be denied that Borel 

 has claimed for Jansen himself the credit of first using the te- 

 lescope for celestial observations without producing any proof 

 of his assertion, and that he has spoken of Galileo in unbeco- 

 ming terms, and has represented him, contrary to truth, and in 

 the face of his own declaration, as denying the source whence 

 he derived his first knowledge of the instrument. Finding the 

 error which I have just mentioned in works of such reputation, 

 and thinking myself also that Borel's account was artfully 

 prepared with a view to produce that very misconception, I 

 thought worth while to observe that John was only six years 

 old in 1609, when the satellites were discovered by Galileo, 

 and that therefore his claim must be put out of consideration. 

 As to the question of Borel's intentions, on which my opinion 

 remains unaltered, I am not so anxious to bring others to 

 agree with me, as to show that I did not venture a i-antlom 

 contradiction of a previous statement, without examination of 

 the point on which I pretended to give an opinion. 



I have one remark only to make on another question con- 

 nected with this subject : Dr. Moll is unwilling to believe that 

 in 1637 the Dutch were inferior to the Italian telescopes, as I 

 asserted on ihe authority of Hortensius, who wrote to Gali- 

 leo that none could be procured in Holland sufficiently good 

 to show Jupiter's disc well defined, and of Gassendi, who 

 wrote to him that he could not procure a good one in Veiiice, 

 Paris, or Amsterdam. Dr. MpU does not notice Gassendi's 



