/;; Heat and riluminate Qhjecisi 315 



^i;5> Experiment. In red rays again. 



Arid here the thermometer, expofed 

 • to red, vole in tive muiules 4 de^ 

 grecs'. 



'/th Experwierit. In greeh rays. 

 Ko, 2. No. 3.-. 



43 J^- 43 i;^ (This made the thermometer riTe, iii 



44 1- 43'^ I the green ra)s, il- degree. 



441- 43 -^ 



8/Z> Exferhnent. Again in green rays. 

 Ko. 2. No. 3. > 



43 43 I Here the rifing by the green rays, 



441 43 [j V.as 2 degrees. 



441- 4ii J 



From there experiments we are alilHorifed to draw the fol- 

 lowing refults : in the red rays my thermometer gave 6|- 

 degrees in the ift, iand 7 degrees in the 2d, for the rifing df 

 ttie quickfilvfer: a mean of both is 6^. In the 3d experiment 

 we had '3^ degrees, for the rifing occafioned by the green 

 rays; from which We obtain the proportion of 55 to 26, 

 fur the power of heating in red to that in green. The 4th. 

 experiment gave ?, degrees fbr the violet rays; and therefore 

 we have the rifing of tht quiekfilver in red to that in violet, 

 ias r^^ to 16. 



A fufficient proof of the accuracy of this deteriilination wc 

 have in the rcfult of the four laft experiments. The rifing 

 for red rays in the 5th, is 2^; and in the 6th, 4 degrees : 

 k nitari of both is 3J-. In the 7th experiment we have ij, 

 iand in the 8th 2 degrees, for the rifing in the green : 4 

 mean of ihefe is t ^ . Therefore, we have the proportion of the 

 rifing in red to that in greeii, as 27 to 11, or as 55 to 22,4» 



We may take a mean of the refult of i)ulh thermometers, 

 wliich will be 55 to 24,2, or mere tlian 2} to i, in red to 

 green; and about 3^ to i, in red to violet. 



It appears remarkable, that the molt fenfible tliermomet'^f' 



fliould give the lead alteration, from the expofure to the co- 



Joured rays. But fince, in thefc clrcumllance?, there are iwp 



canfce confiantlv iicliug difiorent way«: the one to raife tli«t 



ti f 'rs thermotnetir^ 



