DESCRIPTION OF A LAMP. HI 



mechanical lamp when the candles were brought to the diftance 



of 566 centimeters, at the lame time that the mechanical lamp 



was drawn back to 785. The fquares of thefe numbers give 



the ratio of 100 to 52 nearly. If inftead of the latter term 



we put the quotient of its divifion by the number of candles, 



we fee that the light of the mechanical lamp is to that of one 



candle as 100 to llf, or it would require eleven candles and 



a half to give the fame light. 



u As this lamp maybe ufed for the domeftic purpofes of af- The heat it gives 



fording heat as well as for the operations of chemiftry even t0 . oth f T bodl f 

 c r t J placed over the 



in the dry way, it becomes interefting to afcertain the degree flame, 

 of heat it was capable of communicating to veffels placed above 

 its glafs chimney. For this purpofe we took a pyrometricPyrometrlc 

 piece of Wedgwood not baked; it was included between two piece * 

 very thin capfules of platina, and placed on a fupport, firft at 

 four centimeters, where, at the end of half an hour, the con- 

 traction was three degrees of the pyrometric fcale ; after which 

 it was again placed at the diftance of fifteen millimeters only 

 from the upper extremity of the chimney, where, after having 

 been kept for two hours, it was found to have paired the fe- 

 venth degree, which, according to the table of correfpon- 

 dence of Wedgwood, would indicate 505 degrees of the cen- 

 trigade thermometer. 



" A tube of glafs of five millimeters, or two lines, in diame- Tube of glafs. 

 ter, of the weight of thirty-feven decigrams, or fixty-fix grains, 

 the cube decimeter, was eafily bended over the chimney, that 

 is to fay, at eight centimeters, or two inches, &c. from the up- 

 per extremity of the flame. Tin, placed in a fmall crucible of 

 kaolin, upon a fupport of the fame height, flowed in lefs than 

 feven or eight minutes. Five grams, or eighty grains, of an- 

 timony in fmall fragments, afforded in a fimilar crucible, at 

 the end of an hour, a degree of fufion fufficiently advanced to 

 round the lower part of the button, and it is known that the 

 loweft eflimation of the heat required to fufe this metal is 431 

 degrees. 



" The confumptron of oil was determined by feveral trials, Confu motion of 

 one of which was continued for feven hours: It varied very oil « 

 little; the mean term was 34,648 grams per hour. (1| oz. 

 avoird.) 



" With regard to the operative means by which thefe effects Mechanical con- 

 are obtained, we fhali remark, firft, the difpofition of the chim- ftrudMon. 

 ney, which can be raifed or lowered at pleafure by turning the 



cylinder 



