

258 Dr. Herschel's Investigation of the Powers 



the other two close by, in the shade, I marked down what they 

 shewed, at different times. 



No. i. No. 2. No. 3. 



43i - - - 43i - 43* 



48 - - - 43i - 43i 



49i " " - 43i - 43* 



49i - - - 43i - 43i 



50 - - - 43i - ' - - 43i 



This, in about 8 or 10 minutes, gave 6^ degrees, for the 

 rising produced in my thermometer, by the red rays, compared 

 to the two standard thermometers. 



v,d Experiment. As soon as my thermometer was restored to 

 the temperature of the room, which I hastened, by applying it 

 to a large piece of metal that had been kept in the same place, 

 I exposed it again to the red rays, and registered its march, 

 along with No. 2 as a standard, which was as follows. 



No. 1. No. 2. 



45 - - - 45 



4 8 - " " 45 



51 - - - 45 

 51 44t 



51 - - - 44 



Hence, in 10 minutes, the red rays made the thermometer 

 rise 7 degrees. 



$d Experiment. Proceeding in the same manner as before, 

 in the green rays I had, 



