* 



I 



tyin 



Life and writings of Count Rumford. 



\ 



that of one millionth part of the body in question. This being the 

 case, the Count concludes that we may very safely infer, that all 

 attempts to discover any effect of heat upon the apparent weights 

 of bodies will be fruitless. 



t admeasurment of light, although necessary in all com- 



Th 



parisons of the modes of illumination, is nevertheless 



obj ect 



which it is difficult to accomplish with accuracy. The Photome- 

 ter of Count Rumford affords a very good method of comparing 

 the intensity of any two luminous bodies giving light at the same 

 time. The principle of this instrument consists in interposing aa 



object between the 



g bod 



d 



a 



surface 



which it shall cast a shadow fi 



The distance of the 



lights is then varied, until both the shadows become of equal 



tensity. Th 



& 



tted 



be estimated by the 



squares of the distance of tW, iUnminating bodies from the object 



producins: the shadow 



principl 



proportion to the square of the distance 



ght decreases 



la 



Some experiments relating to the transmission of heat through 



led the 



Count to suppose that fluid 



of heat, and that 

 or change of pi 



non conductor 



mitted 



hich occurs amons 



by 



particles 



TI 



opinion however has been set aside in consequence of the experi- 



lists, and the Count himself is said ultimately 



ments of 



have given it up 



But 



most valuable of Count Rumford 



hich 



researches, and 



have shed the most imperishable glory upon 



much his ntfpmnfa »t rl«.r,.i^.>:„_ i 



his attempts 



el op 



of matter, as his successful and fortunate application of 

 ready known to the use and convenience of mankind 



lawH 



* 



la the 



