late Professor of Practical Astronomy in Glasgow. 29 1 



tions of London for 1774. Not long after he entered upon this 

 new field, the nature of the solar spots was announced by the 

 Royal Society of Copenhagen as the subject of a prize essay. 

 This induced him to transmit thither a paper written in the La- 

 tin language, containing an account of his observations, and of 

 the conclusions drawn from them. In return, he obtained the 

 honourable distinction of a gold medal of near sixteen guineas 

 intrinsic value, having, on its reverse, the figure of Truth pen- 

 dent in the air, holding a wreath in one hand, and in the other 

 a perspective glass, and the motto, Veritati luciferce. 



As an astronomical observer, he was remarkable for a sharp 

 and clear eye, devoid of all blemish, and which, too, without be- 

 ing liable to fatigue, had long been inured to examine and to 

 judge of small objects in their nicest proportions ; a circumstance 

 which must have proved of great advantage to him, when em- 

 ploying his sight upon celestial appearances by means of the te- 

 lescope ; and it required only to know him, to have the fullest 

 assurance of his fidelity in rendering an account of his observa- 

 tions. 



His discovery in regard to the solar spots, though it be gain- 

 ing ground more and more among those most conversant in astro- 

 nomy, yet, like many other new discoveries, has not escaped its 

 share of opposition. This gave him occasion to publish, in the 

 Philosophical Transactions of London for 1783, the second pa- 

 per upon that subject, after a silence of near ten years, wherein, 

 upon the authority of many more observations made in that in- 

 terval, he obviates objections, and maintains the reality of his 

 discovery, with an entire conviction. The amount of it is, " That 

 the spots are cavities or depressions in that immensely resplen- 

 dent substance which invests the body of the sun to a certain 

 depth ; that the dark nucleus of the spot is at the bottom of this 

 excavation, which commonly extends downwards to a space equal 

 to the semidiameter of our globe ; that the shady or dusky zone 



