NATURAL HISTORY OF SELBORNE 157 



sion, and why their webs should at once become so gross and 

 material as to be considerably more weighty than air, and to 

 descend with precipitation, is a matter beyond my skill. If I 

 might be allowed to hazard a supposition, I should imagine 

 that those filmy threads, when first shot, might be entangled 

 in the rising dew, and so drawn up, spiders and all, by a brisk 

 evaporation, into the regions where clouds are formed : and if 

 the spiders have a power of coiling and thickening their webs 

 in the air, as Dr. Lister says they have [see his Letters to Mr. 

 Ray], then, when they were become heavier than the air, they 

 must fall. 



Every day in fine weather, in autumn chiefly, do I see those 

 spiders shooting out their webs and mounting aloft : they will 

 go off from your finger if you will take them into your hand. 

 Last summer one alighted on my book as I was reading in the 

 parlor ; and, running to the top of the page, and shooting out 

 a web, took its departure from thence. But what I most won- 

 dered at was, that it went off with considerable velocity in a 

 place where no air was stirring ; and I am sure that I did not 

 assist it with my breath. So that these little crawlers seem to 

 have, while mounting, some locomotive power without the use 

 of wings, and to move in the air faster than the air itself. 1 



NOTE 



1 The appearance of the gossamer-covered fields will be familiar to all 

 who live in the country. It seems clear that the "locomotive power" of 

 the tiny spiders is due solely to the movement of the atmosphere. On the 

 quietest days, if you will wet your finger and hold it up, you will find it grow 

 sensibly cooler on one side than the other, and on that side is there a faint 

 wind blowing. If you will then watch the spiders, you will see them shoot 

 out long silvery threads, which will incline to leeward, and presently the 

 spiders will let go their hold of the grass, and launch themselves into the 

 air, floating away on the slightest movement of it. 



