30 0« the Solar Eclipse 



He also on the same day submitted the bulb of a thermome- 

 ter (which theu stood at 66") to the focus of the lens ; and in 

 1^ minute it rose to 94°, and probably would have risen higher, 

 had he not been apprehensive that the glass would have been 

 broken by the heat. These experiments were made at about two 

 o'clock in the afternoon, in order that they might correspond 

 with the time of the eclipse at its greatest obscuration. On 

 the following day, about half an hour after the commencement 

 of the eclipse, he applied the cloths in succession to the focus 

 of the lens, and found the periods, at which they respectively 

 took fire, to be as follow : viz. 



Black in 20" 



Blue 20 



Red 16 



Yellow 40 



At about half an hour before the end of the eclipse he again 

 submitted them to the focus of the lens, and found their periods 

 of ignition to be as under : viz. 



Black in 17" 



Blue 18 



Red 14. 



Yellow 24 



But during the time of the greatest obscuration he could not 

 produce any effect on them whatever. The thermometer at the 

 commencement of the eclipse was at 66°; and by two o'clock 

 Jiad fallen to 6 1 1. This was about the middle of the eclipse : 

 and Mr. Wiseman assures me that at this time he held the 

 bulb in the focus of the burning tens for upisoards of four minuteSy 

 hut rvithout 2)^oducing any sensible effect. At a (juarter past 

 two, he repeated the smne experiment, and with the same re- 

 cult, although the sun was free from clouds. At the termina- 

 tion of the eclipse the thermometer rose to 64 '. Mr. Wise- 

 man also states, that he fitted up a prism in a darkened room, 

 and that he made several observations on the colouied rays, 

 which were thrown on a screen of white paper. He says that, 

 during the continuance of the eclipse, the yellow and blue rays 

 were generally increased in brilliancy, whilst the red became 

 exceedingly tiiint, and did not occupy more than hjilf their 

 usual breadth. As I am not aware that any experiments of a 

 similar kind were made during this eclipse, and as the results 

 are somewhat singular, although anticipnletl by Mr.\\'iscman, I 

 have thought it right to state them here in order that the atten- 

 tion ot the public may be excited thereto in any future eclipse. 



Mr. SloiMie of Belfast informs me that the eclipse com- 

 menced there at IP 47' 3S" mean solar time : the observation 

 was made with one of Dollond's achromatic telescopes, m.-ig- 

 nif^-ing about 75 times. At 



