On tbe Korlhern Magnetic Pole of the Earth. 249 



canftruiSled, which renders the aftion of the current of air 

 much more moderate, and prevents the coufumption of the 

 wood, and perhaps of a part of the hydrogen, which it is ef- 

 fentially nectlFarv to preferve in the charcoal. 



tth. By the practice followed at Benou of throwing a cer- 

 tain quantity of water over the furnace when the wood is 

 charn.d. 'I'iiis pra^lice is not n;eutioned in the works al- 

 ready alI'.Kled to. 



The forells of Chizai and Aunai, which, except that of 

 Bcrion, are neareft to Rochelie. furniili charcoal, which is fa- 

 bricated alfo from pieces of wood of the fame fize, which are 

 put into the furnace in like manner without being fplitj 

 but the; difference in the choice of the wood, and particularly 

 in the fabrication, which takes place in the open air, makes 

 a difference of 25 or 30 per cent, in the price of the char- 

 coal. This difference is fomctimes greater when compared 

 ivilh that of other forefrs. 



In the proccfs therefore here defcribed, there is a favingof 

 wood, and at the fame time the product acquires a greater 

 vatu£. 



XXXVIII. On the Northern Magnetic Pole of the Earth, 

 jy>' Jkbome Lalande *. 



I 



T lus been known for more than two centuries, that the 

 mas:netic needle does not point exaftly north, and that its 

 clecTinaiion from that direcStionIs different in diiTcrcnt places. 

 Rcfearches therefore have been made to determine the point 

 of the earth towards which the magnetic needle turns; and 

 this object engaged the attention of Dr. TJalley in 1683, of 

 tuler in 1745, of Lemonnier in 1776, and of Buffon in 

 1788. About five years' ago Mr. Churchman, a native of 

 America, came to Paris to induce govcrnurcnt to fct on foot 

 a voyage to the north pole, for the purpufe of determining 

 the polition of the magnetic pole in the north, in the year 

 1794 he publiflicd a work, in which he projjofcs a theory by 

 which the declination of the magnttic needle can be deter- 

 mined for different periods and different places. I endea- 

 voured to compare it with the latcd obfervutions. Thofe of 

 which 1 have already fpoken in the Conno'iflance dcs T<ins^ 

 were made at Noolka Sound in 48 36' north lat. and \l(f 

 long, well from Paris, in the year 1778; and the declina- 



' From tbe Connoijfuice cits Tt/i/s four I'an. vii. 

 t All. iv. \i. iij. 



lion 



