MOTIONS OF INSECTS. 339 



a much more reasonable supposition than the other; bui 

 some facts seem to militate against it : for, in the first 

 place, though gossamer often occurs upon the ground 

 when there is none in the air, yet the reverse of this has 

 never been observed ; for gossamer in the air, as in the 

 instance recorded by Mr. White, is always preceded by 

 gossamer on the ground. Now, since the weather is 

 constantly calm and serene when these showers appear, 

 it cannot be the wind that carries the web from the 

 ground into the air. Again, it is stated that these show- 

 ers take place after several calm days ^ : now, if the web 

 was j'aised by the wind into the air, it would begin to 

 fall as soon as the wind ceased. Whence I am inclined 

 to think that the cause assigned by Dr. Lister is the real 

 source of the whole phenomenon. Though ordinary ob- 

 servers have overlooked them, he noticed these spiders 

 in the air in such prodigious numbers, that he deemed 

 them sufficient to produce the effect. I shall not, how- 

 ever, decide positively ; but, having stated the different 

 opinions, leave you to your own judgement. 



The next query is, What occasions the spiders to 

 mount their chariots and seek the clouds ? Is it in pur- 

 suit of their food ? Insects, in the fine warm days in 

 which this phenomenon occurs, probably take higher 

 flights than usual, and seek the upper regions of the at- 

 mosphere ; and that the spiders catch them there, ap- 

 pears by the exuviae of gnats and flies, which are often 

 found in the falling webs ''. Yet one would suppose that 

 insects would fly high at all times in the summer in 

 serene warm weather. Perhaps the flight of some par- 

 ticular species constituting a favoui'ite food of our little 



" Ray's Letters, 36, '' Ibid. 42. Lister De Araneis, 8. 



Z 2 



