of the iTwiJlhWRays of the Sun. II 



No. 2. No. 3. No. tf.i Here the thermometer No. 2 



44 44 45 rofe 2' degrees in 12 mi- 



47 44 45 f nutes; and being, as has 



46I 44 45 been noticed before, muck 



46| 44 45 J more fenlible than No. 1, 



it came to the temperature of its fituation a fhort time; but 



I left it expofed longer, on purpofe to be perfectly allured 



of the refult. Its mowing but %\ degrees advance, when 



No. 1 mowed 6^, has alfo been accounted for before. 



It being now evident that there was a refraction of rays 

 coming from the fun, which, though not fit for virion, were 

 yet highly inverted with a power of occasioning heat, I pro- 

 ceeded to examine its extent as follows : 



The thermometers were arranged on the third line inftead 

 of the fecond ; and the ftand was, as before, immerfed up to 

 the firft, in the coloured margin of the vanifliing red ravs. 

 The refult was thus : 



I placed now the thermometers on the fourth line inftead 



of the third j and, proceeding as before, I had the following 



refult : 



No. 1. No. 2. No. 3.^ Therefore, the thermometer 

 48 h 48 h 47? f No. 1, rofe 3^- degree in 



5 1 ? 4 8 ! 47 f J I0 minutes, at ii inch 



beyond the vifible light of the red rays. 



I might now have gone to the fifth line ; but fo fine a day, 

 with regard to clearnefs of fky and perfect calmnefs, was not 

 to be expected often at this time of the year; I therefore 

 haftened to make a trial of the other extreme of the prifmatic 

 fpectrum. This was attended with fomc difficulty, as the 

 illumination of the violet rays is fo feeble, that a precife ter- 

 mination of it cannot be perceived. However, as well as 

 could be judged, I placed the thermometers one inch be- 

 yond the reach of the violet rays, aud found the refult as 

 follows : 



C % No. 



