186 &quot;I NATURAL HISTORY. 



whereupon the lamp standeth : make only one hole 

 in it, at the end of the return farthest from the 

 turret. Reverse it, and fill it full of oil by that hole ; 

 and then set it upright again ; and put a wick in at 

 the hole, and lighten it : you shall find that it will 

 burn slow, and a long time : which is caused, as 

 was said last before, for that the flame fetcheth the 

 nourishment afar off. You shall find also, that as 

 the oil wasteth and descendeth, so the top of the 

 turret by little and little filleth with air ; which is 

 caused by the rarefaction of the oil by the heat. It 

 were worthy the observation to make a hole in the 

 top of the turret, and to try when the oil is almost 

 consumed, whether the air made of the oil, if you 

 put to it a flame of a candle, in the letting of it forth, 

 will inflame. It were good also to have the lamp 

 made, not of tin, but of glass, that you may see how 

 the vapour or air gathereth by degrees in the top. 



374. A fourth point that importeth the lasting 

 of the flame, is the closeness of the air, wherein the 

 flame burneth. We see that if wind bloweth upon 

 a candle it wasteth apace. We see also it lasteth 

 longer in a lanthorn than at large. And there are 

 traditions of lamps and candles, that have burnt a 

 very long time in caves and tombs. 



375. A fifth point that importeth the lasting of 

 the flame, is the nature of the air where the flame 

 burneth ; whether it be cold or hot, moist or dry. 

 The air, if it be very cold, irritateth the flame, and 

 maketh it burn more fiercely, as fire scorcheth in 

 frosty weather, and so furthereth the consumption. 



