^Sfy PHILOSOPHICAL TRANSACTIONS. [anNO 1775. 



should have been continued down into the moist earth or water ; and had not 

 the earth, as Mr. HafFenden observes, flowed with water, at the time of the 

 accident, the want of this precaution might perhaps have been attended with 

 some damage to the foundation. In Mr. HafFenden's 2d letter, he observes, 

 that the bell wire, mentioned in his first letter, was brass ; and that so much 

 of it as went through the passage painted : and the painted part, he says, was 

 not destroyed ; but the paint was loosened on the wire, without being broken 

 off, like the loose rind of a tree ; which resembles the effect of the artificial 

 electricity, in an experiment of Mr. Kinnersley's, where a wire was, by a great 

 explosion, both lessened in diameter, and extended in length. The other part 

 of the wire, which was not painted, except a short piece at the end, somewhat 

 larger and of iron, was entirely melted. Query, if the wire before spoken of 

 had passed through a stone, particularly a wet one, inclosing it firmly, would 

 not that stone have been shivered to pieces ? 



XXIII. On the Torpidity of Swallows and Martins. By James Cornish, 

 Surgeon, Totness, Devon, p. 343. 



In the beginning of November, Mr. C. being fishing on the banks of the 



river Dart, which runs at the bottom of a very steep hill, from the side of 



which project several large rocks, overgrown with ivy and thicket ; he was at 



once surprised with the sight of a great number of martins. He desisted from 



his amusement, the more carefully to observe the birds, which he concluded 



had been brought out of their winter quarters by the fineness of the afternoon, 



it being remarkably pleasant and warm for the time of the year ; the sun at that 



time darting its rays directly against the rocks, just opposite to which Mr. C. 



had fixed his station. They continued to flit to and fro for near half an hour, 



keeping very near together, and never flying in a direct line above 30 or 40 



yards, and never, when at the farthest, above 100 yards distant from the rocks ; 



closer to which they now, as the sun lowered, began to gather very fast. Their 



numbers now lessened considerably ; and in a very short time they all returned 



into the fissures of the rocks, whence they had been induced to venture out by 



the warmth of the evening. Mr. C. was particularly careful to observe if there 



was a swallow among them ; but there was not one. Of this he was certain ; 



for they were several times within the distance of 20 yards from the places where 



he stood. He was the more attentive to this, as he had been repeatedly assured, 



by many masters of vessels in the fish trade, that they constantly saw every 



autumn, as they sailed up the Mediterranean, vast flights of swallows, bending 



their course towards the south. From which there is the strongest reason to 



believe, that these birds seek a warmer climate during the winter months; 



