218 PHILOSOPHICAL TRANSACTIONS. [aNNO J 685. 



of a span breadth, could make observations, 30 or 40, or 50, and even 6o 

 times more accurate, than could be done the other way with the largest instru- 

 ments. And, on the author's publishing that first part of his Machina Coelestis, 

 wherein all his instruments are accurately described, Mr. Hook published his 

 animadversions thereon ; with much more of bitterness and boasting, as this 

 author thinks, and others also whom the author cites, than there was reason 

 for : thus seeking to raise his own reputation by disparaging what is done by 

 others, in things wherein himself does nothing. 



The author thinking the credit of his observations to be herein much con- 

 cerned ; he complained hereof in his letters to several learned men, and parti- 

 cularly to the Royal Society, desiring that justice might be done him in this 

 point. For that a difference of this nature was not to be determined by con- 

 jectural speculations, which a man may project to himself; but by practical ex- 

 perience, and trials actually made both ways ; and these duly examined and 

 compared by persons competent to judge of such matters. 



In order to this, the author had often and earnestly desired that Mr. Hook 

 would vouchsafe to give him at least these 8 distances, observed by his instru- 

 ments, great or small as he pleased, to be compared with the same observed by 

 this author: viz. 1. Lucidae Arietis ^ Palilicio ; 2. Hujus k Polluce ; 3. Pollucis 

 a Regulo ; 4. Reguli a Spica Virginis ; 5. Hujusque k superior! in manu Ser- 

 pentarii ; 6, Hujus ab Aquila ; 7. Hujusque k Marcab ; 8. Atque hujus demum 

 i Lucida Arietis : but could never obtain from him either these or any other ; 

 though it could be no hard request to grant, if Mr. Hook could, as he says, 

 perform according to his method 100, or 200 observations in one night. 



He had from Bulliald, Buratin, Fullen, and others, who had been eye-wit- 

 nesses of his observations, and assistant at them, great attestations of their 

 accuracy: others who had not so been present, had yet a great esteem for them, 

 notwithstanding the exceptions made to them by Mr. Hook; blaming his cen- 

 sure as undeserved and too severe: and others even of those who had a great 

 opinion of telescopic sights, and did themselves make use of them, had yet a 

 far other opinion of his instruments and observations, than what had been ex- 

 pressed by Mr. Hook ; and thought at least this demand of his very reasonable, 

 that it might be free for either to make use of such sights as themselves thought 

 best, or were best acquainted with, without taking upon them to prescribe to 

 others, or to reproach and vilify them because not of the same opinion with 

 themselves. 



In consequence then of his request, the Royal Society sent Mr. Halley to 

 Dantzic, where he arrived May 26, 1679, and there continued with the author 

 till July 18 } being all that time a constant attendant at his observations ; and 



