on the terrestrial Rays that occasion Heat. 503 



Making now black paper the standard, and supposing it to 

 scatter 1000 rays of heat, and the same of light, then black vel- 

 vet scatters 1 179 rays of heat, and only 17 of light. This last 

 number we obtain, by dividing the tabular number 7, for black 

 velvet, by ,42, which is the proportion of black paper to white. 



209^ Experiment. 



Black paper. Black muslin scattering, 



°' 75i 75i 



Black muslin scatters 1192 rays of heat, and 43 of light. 

 2iotb Experiment. 



Black paper. Black satin scattering. 



0' 76^- 76-t 



5 79 8oi . . . 2| : 3f = 1,409 



Black satin scatters 1409 rays of heat, and 243 of light. 



Qiitb Experiment. 



Having now ascertained, that of all the white and black sub- 

 stances I had tried, white muslin scatters the least, and black 

 satin the most heat, I placed the former on one tablet, while the 

 latter was put on the other. 



White muslin. Black satin scattering. 



5 80 80^... 3^:3^=1,0% 



Here the black object scattered more heat than the white 

 one ; but, in order to try again the equality of the tablets and 

 apparatus, I placed the objects under the opposite thermome- 

 ters, and had as follows. 



3 Ta 



