401 PHILOSOPHICAL TRANSACTIONS. [aNNO ITQJ, 



For about five minutes the lustre remained pretty strong and vivid, and the 

 meteor without any visible change or variation ; but, after the expiration of that 

 short term, the arch began to grow faint, and in one or two minutes more totally 

 disappeared. 



How long this meteor had been formed, when Mr. S. first observed it, he 

 cannot say ; but he believed it was then, and perhaps for some time had been, on 

 the decline. The crepusculum, or illustration of the atmosphere, which some- 

 times precedes such meteors as this, and even continues long after their extinction, 

 might perhaps have remained till 10 or 11 o'clock; which if we admit, this 

 crepusculum may not improbably be considered as the same phenomenon with 

 " a surprising bright luminous appearance visible at London in the hemisphere 

 from the E. to the w. about 10 o'clock, which lasted about an hour," the same 

 night, or at least as something similar to it. 



The singularity of this meteor was fixed by the gradual and regular diminution 

 of its resplendency between the upper and lower limbs, an instance of which he 

 never observed before. This continued from the time he first discovered the 

 arch almost to the very moment of its extinction. The limbs of the zone 

 forming this arch were however very well defined; insomuch that the regularity 

 of its figure, by the gradual decrease of brightness, was not in the least impaired. 



XIII. Some Observations on Swarms of Gnats, particularly one seen at Oxford, 

 August 20, 1766. By the Rev. John Swinton, B. D., F. R. S. p. 1 1 1. 



The gnats have been more numerous, as well as more noxious, here, (Oxford) 

 during the months of July, Aug. and Sept. 17 66, than perhaps they were ever 

 known to be before in the memory of man. So many miriads of them have 

 sometimes occupied the same part of the atmosphere, in contiguous bodies, that 

 they have resembled a very black cloud, greatly darkened the air, and almost 

 totally intercepted the solar rays. The repeated bites likewise of these malignant 

 insects have been so severe, that the legs, arms, heads, and other parts, affected 

 by them, in many persons, have been swelled to an enormous size. The colour 

 also of these parts, at the same time, was red and fiery, perfectly similar to that 

 of some of the most alarming inflammations. 



Mr. S. takes notice of one very remarkable property of these little mischievous 

 animals, which lately presented itself to his view, and which has not yet perhaps 

 been duly attended to by any naturalist. Being in the garden belonging to the 

 fellows of Wadham College, August 20, 1766, about half an hour before sun- 

 set, such an immense immber of gnats filled the atmosphere, as he had never 

 seen before. He then observed 6 columns, formed intirely of these insects, 

 ascending from the tops of 6 boughs of an apple-tree, in another garden, sepa- 

 rated from that he was in by a partition-wall, to the height of at least 50 or 60 



