D(fcription of an Air Furnace. \ 547 



lioifted at the flag ftafF, and in the afternoon they come to an anchor, fo that the owners 

 of the boats are thereby, enabled to get their cargoes out before night, which may amount 

 to 30,000 oyfters, if the divers have been aftive and fuccefsful. 



Each boat carries tw,enty-one men and five heavy diving ftones for the ufe of ten divers, 

 who are called in Tamul, kooly karer, the reft of the crew confifts of a tandel, or head 

 boatman J and ten rowers, \<'ho alTift'in lifting up the divers and their (hells. 



(To be continued.) 



VI. 



Defcription of the Air Furnace ofCiT, Lecour. 



HE air furnace, of which a feftion is given in Plate XXIII. Fig. 2, was ufed in the 

 experiments defcribed page 134 of our Journal, and is taken from the fame report of Guy- 

 ton. It is conftrudted of brick; its fire-place being 25 centimeters fquare (9! inches) 

 within, and 45 (17^ inches) in height. It is clofed on one fide by an iron cover, inclined 

 about 25 degrees." The chimney, which is alfo of brick, is 25 centimeters fquare below, 

 and one-fifth lefs at top, namely at- an elevation of 1 3 decimeters (about 4 feet '3 inches) 

 where it enters into a large chimney, about 15 metres (or near 5 feet) high, the excefs of 

 which is clofed by a kind of door. " 



In this furnace the heat was raifed to about 150 pyrometree degrees of Wedgwood. 



VII. 



On Ike Lamp for Tallow, and the Combujiion of that Material. By Mr. William Close. 



To Mr. NICHOLSON. 

 SIR, 



S 



OON after the defcription of the lamp for burning tallow was fent to you, I made a. lit- 

 tle addition to the apparatus, which makes it more convenient. 



For an appendix to the preceding detail, I fend you an account of the new arrangement. 



And am, Sir, your humble fervant, 



WILLIAM CLOSE. 



Dalton, fan, 2^thy 1800. 



The 



