»N tHE NATURE OF HEAT* J93 



tit 



An Enquiry concerning the Nature nf Heat, and the Mode 'i 6/ 

 ^ its Communication. By Benjamin Coimt of Rumkord; 

 ' V. P. R: S, S^'C. Abridged from the Philofophicdl Tranf- 

 • daionsfor 180'K 



(Concluded from p. 63.) 



Exp. 12. Jt WO equal cylindrical veflfcls of flieet brafs po-Exp. 12. Bo- 

 iiflied very bright, each three inches in diameter and four '^'^ ^^'^^ *" ^^^ 



• ■^ ° • i • 1 • • refpects and 



inches long, fuipended by their oblique necks in a horizontal {seated, do, at 

 pofition, beins: placed on their wooden ftands, were filled ^^^'^^ dutances, 



. . ■ n ^n 1 f • • in affed the ther- 



with water at the tentperatnte of 180^ ; and their circolar flat mofcope equally. 

 bottoms were prefented, in a rertical pofition, to the two 

 balls of the thermofcope; at the diftance of two inches. 



When thp two hot bodies were prefented, at the fame mo7 

 ment, to the two balls of the infirument^ or what was ftill 

 better, when two fcreens were placed before the two balls, 

 at the diftance of about an inch, and, after the hot bodies 

 were placed, thefe fcreens were both removed at the fame 

 inftant, the bubble remained without motion in the middle 

 of the horizontal part of the tube of the inftrument. 



If the diftances of the equally hot bodies were rendered 

 unequal, the bubble always moved towards the mofl remote 

 of the two; and if a fingle hot body was prefented to one 

 of the balls, the bubble was driven from it, and might have 

 been carried quite out of the tube; which, however, wa? " 

 always avoided, as the inftrument would have been by that 

 means quite deranged. ' , , 



Exp, 1-3. The flat circular bottom of one of the cylii>drical Ex-p. 13. A cy. 

 veflels was blackened by holding it over the flame of a wax lender blackened 



r- I • - 1 • I 1 /• w . w^" imoke, 



candle; the other vetlel remaining pr'ght as before. Both gives out moi;e 

 were then filled with water at 130^, and prefented at equal radi.nt heat thin 

 diftances to the two oppoflte balls of the inftrument, as de- furfac?. 

 icribed in the laft experiment. 



The bubble was inftantly driven out of its pl^ce by the 

 i'uperior adion of the blackened furface; and it did not return 

 io its former ftation until the blackened furface had Leen re» 

 moved to more than eight inches from the ball to which it was 



Vol. IX. — November, 1804. O prefented j 



