When fwivimivg in a B A S N of OIL, &cc. 1 7 1 



liandling it ; and, after the wick is touched v/ith a drop of oil, 

 it is ready for being Ughted. For this purpofe, a bit of pack 

 thread, which has been fteeped in oil, is a cleanly and conve- 

 nient match, and fheds no impurities on the oil, as a candle or 

 wax taper would do. 



When you want the lamps to circulate, the oil mull be very 

 pure, and brought into full contadt with the lides of the glafs. 

 The oil, and the bafon or falver, fliould all be allowed to come 

 to the fame temperature, between ^^'' and 60° of Fahrenheit. 

 For if any part of the brim be much hotter than the reft, the 

 lamp, on arriving there, will leave the fide, by the current ilTu- 

 ing from the heated part forcing it away. 



Sometimes the lamp, when failing, veers a little into a diffe- 

 rent diredtion, by the bafe altering or warping by the {torching 

 heat of the flame, which determines the ftream to flow out mofl 

 copioufly at a different part of the bafe. 



In the melted greafe which lies round the wick of a common 

 candle when lighted, there are fometimes obferved atoms, which 

 have been left by the fnuffers, moving to and from the flame 

 continually. Thefe motions have been conceived by fome as 

 occafioned by attractions and' repulfions, in confequence of an 

 eledlrical quaUty imputed to the flame. It fliould feem, how- 

 ever, that they depend merely upon oppofite currents at the fur- 

 face, and immediately below the furfacc of the melted greafe, 

 according to the principle above explained. 



X 2 VII. 



