VOL. XXXVI.] PHILOSOPHICAL TRANSACTIONS. SSS 



The kingdom of Tunis is bounded to the north and east with the Mediter- 

 ranean sea, to the west with the kingdom of Algiers, and to the south with 

 that of Tripoli. It is 230 miles in length, from the isle of Gerba, in latitude 

 33° 24', to Cape Serra, in latitude 37" l&, and 128 miles in its greatest breadth 

 from Monasteer to Tibesa. Sbeka, its utmost boundary to the west, lies in long. 

 7° 26', and Clybea, its utmost boundary to the east, in 10° 47' from London. 



Mr. Shaw, from his observations, corrects most of the geographical writers, 

 both ancient and modern, concerning the situation of places, &c. but of these 

 it is not necessary to enter into a detail here. 



^ brief Account of some of the Effects and Properties of Damps. By Mr. Isaac 

 Greemvood,Prof, of Mathematics at Cambridge, New England. N° 41 I, p. 184. 



July 19, 1729, two men being employed to repair a pump in this place, un- 

 covered the well; on which one of them immediately attempted to go down, 

 by means only of a single rope, but had not descended above 5 or 6 feet before 

 he was rendered incapable of sustaining his weight, and without speaking, or 

 any signals of distress, slipped down suddenly to the upper part of the joint 

 of the pump, where being supported about a minute, fetching his breath in a 

 very distressed manner, he fell to the bottom, which was about 8 or 10 feet 

 lower, and (-overed with but a very few inches of water, without discovering any 

 signs of life. On which the other hastily took the rope in his hand, to descend 

 to the relief of the former; but at the same distance from the top, met with the 

 same fatal interruption, and without discovering any signs of distress, was heard 

 to fall to the bottom. 



The workmen above prepared a third with a tackle about his waist. On his 

 descent he was rendered speechless, and made no signs at all, though he had 

 agreed to it; on being raised from the well, he appeared as dead: but on the 

 use of proper means was soon recovered, without remembering any thing parti- 

 cularly that had passed. Some hours after this the other bodies were taken up, 

 with all the marks of a violent death upon them. 



Next evening several trials were made on descending lights, particularly, by 

 letting down lighted candles uncovered, others enclosed in lanterns, and others 

 with the lantern placed in a pail ; but in all these endeavours it was observed, 

 that whatever the circumstances of the descending lights were, it never reached 

 above 6 feet before extinguishing. 



July 20, Mr. G. repeated this evening such experiments in the damp as related 

 to flame, and found the effect much the same as before, viz. in about 6 feet 

 below the top of the well, the flame would grow dim, and if not immediately 

 raised would change to a bluish colour, and become more and more contracted 

 or diminished, till in about a minute's time it would be totally extinguished. 



