124 THE LIFE OF JAMES D. FORBES. [CHAI-. 



Optics contain surfeit of demonstration which would 

 not now be tolerated ; and as the habit of estimating both 

 mathematical and experimental evidence advances, the 

 chances of error by abridged processes of reasoning an- 

 diminished, higher powers of mental abstraction are pro- 

 duced, and a degree of sagacity brought to bear upon all 

 kinds of questions which perhaps more than compensates 

 for what the sciences may have lost in the ambitious 

 display of continuity of reasoning. . . .' 



To Miss FORBES. 



' EDINBURGH, May 2lst, 1836. 



'. . . The eclipse was admirably seen here, and seemed 

 to strike every sort of person much more than they 

 expected. I was making optical experiments in a dark 

 room most of the time, but ran out for half a minute to 

 see the ring, which was a wonderful sight. I sent you an 

 account in the Advertiser. Dr. Chalmers preached, and 

 I managed to hear him, too. Evening service was post- 

 poned in the churches and chapels, except Mr. Bagot's, 

 and the smoking of glass and the burning of fingers 

 and blacking of faces was wonderful. . . / 



His travels during the summer of 1836 were confined 

 to his own country, followed by a short visit to England. 

 In the same month, May, as that in which he watched 

 the annular eclipse of the sun at Edinburgh, he explored 

 the Lead Hills, returning by Moffat and St. Mary's Loch. 



The following letter refers to this tour : 



To PROFESSOR JAMESON. 



'June 1st, 1836. 



' . . . On occasion of a late visit to the district of 

 Lead Hills I suggested to my friend and former pupil, 

 Mr. Irving, of Newton, the importance of determining 

 the temperature of the springs in the bottom of the Lead 

 Hill Mines at this particular epoch. The working having 

 been discontinued since the end of March, any supposed 

 influence of animal heat and light is avoided, and yet 



