in closed Fire-places. 503 



ascertained that point by the following experiments 

 and computations. 



I supposed a small family, consisting of two persons, 

 to drink tea twice every day (morning and evening) 

 during one whole year, and that 2 pints of water, at the 

 temperature of 55 (the mean annual temperature of 

 the atmosphere in Great Britain), was heated and made 

 to boil every time tea was made. 



I found on inquiry that the most costly fire-wood that 

 is sold in London, dry beech in billets, at the high- 

 est price it is ever sold at, cost one farthing per lb., 

 avoirdupois weight; that is, at the rate of twopence 

 per billet, weighing at an average 8 Ibs. By whole- 

 sale, these billets are sold in London at one penny half- 

 penny each. 



I had some of these billets sawed into lengths of 

 about 5 inches, and then split into small pieces (about 

 the size of the end of one's little finger), and bound up 

 with a pack-thread into little small bundles weighing 

 about 4 or 5 ounces each. In the middle of each 

 bundle there were a few smaller splinters and a very 

 small piece of paper, that the bundle might easily be 

 set on fire with a candle or with a common match. 



On using the small portable furnace represented in 

 the Fig. 63, and described in Chapter XI. of the tenth 

 Essay, page 414, and the small tin tea-kettles repre- 

 sented in the Fig. 68, in that Essay, I found by an 

 experiment, which was repeated several times, that I 

 could boil 2 pints of water with a bundle of wood 

 weighing 4 ounces. 



Hence it appears that the daily consumption of 

 wood in boiling water for tea for two persons would 

 be 8 ounces, or half a pound weight ; consequently, for 



