182 NATURAL HISTORY 



these apterous insects should that day take such a wonderful 

 aerial excursion, 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 region 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 be- 

 come 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 parlour ; and, running to the top of the page, 

 and shooting out a web, took it's departure from thence. But 

 what I most wondered at was, that it went off with consider- 

 able 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 loco-motive 

 power without the use of wings, and to move in the air faster 

 than the air itself*. 



* [The phenomenon of gossamer has engaged the especial attention 

 of many observers since Gilbert White wrote the graphic description 

 in the text. After the notice by Kirby and Spence in their admirable 

 'Introduction' (vol. i. letter xiii.), the subject has been repeatedly 

 treated of by Mr. Blackwall, the well-known arachnologist, whose first 

 paper appeared in the Linnean Transactions of 1827. In the ; Zoological 

 Journal/ vol. v. is a further discussion by the same author, which is 

 repeated in his book on British Spiders, published by the Ray Society. 

 These treatises are well worth studying, although perhaps scarcely satis- 

 factory. It appears clear, however, that the movements of the spider 

 are guided by atmospheric causes, and that its ascent is due to the 

 extreme tenuity of the web, and to the motion given to it by the air ; 

 and that if the connexion of the spider with the web be cut off, the 

 insect falls to the ground, while the buoyant web continues its course 

 under atmospheric impulse. T. B.] 



