THE AERONAUTIC OR BALLOONING HABIT. 279 



This is a natural, and undoubtedly is the true, explanation of gossamer 

 showers. The theories which have attributed them to electrical phenomena, 

 or to the shooting out of threads from the spinnerets by the physical 

 power of spiders before their ascent, must be dismissed as having no foun- 

 dation in fact. They are really no more worthy of credit than the popu- 

 lar superstition that these fleeing cobwebs are 



"Caused by the autumnal sun, 

 That boils the dew that on the earth doth lie." 



The French naturalist Mr. Virey made certain observations and ex- 

 periments which led him to conclude that spiders " swim in the air " by 

 approximating their limbs and striking the air as birds or insects do their 

 wings. Moving the feet with incredible agility, they are able by means 

 of the vibration to propel themselves through the atmosphere. 1 In this 

 bold but fanciful conjecture, as Blackwall properly terms it, Mr. Virey was 

 anticipated by Dr. Lister. " Certainly this is a rope dancer," he writes, 

 " and itself effects its ascent and sailing. For, by means of its legs, closely 

 applied to each other, it balances itself, as it were, and promotes and di- 

 rects its course no otherwise than as if Nature had furnished it with 

 wings or oars." 2 



Notwithstanding the importance which such names give to the suppo- 

 sition, it is thoroughly unworthy of belief. The only movement which I 

 have ever perceived on the part of spiders is a momentary adjustment of 

 their bodies, so as to swing them between "the two floating rays of threads 

 that constitute their balloon; and, also, to spin the little foot basket or 

 support for their feet, which I have heretofore described. Otherwise they 

 appear to remain perfectly quiet until they reach the ground and escape 

 from their aeronautic threads. 



It is hardly worth while to more than mention the theory of Murray 

 that the ballooning ascents of spiders are caused by electricity. 3 The the- 

 ory was much mooted at one time, and had some worthy names 

 .... to endorse it. It is, of course, not impossible that a material 



composed of silk, as is the spinningwork of spiders, may be in- 

 fluenced more or less, and in one way or another, by electricity. But as the 

 result of careful, long continued, and wide observation and study I have 

 no hesitation in saying that electricity has nothing (or next to nothing) 

 to do with the ballooning of spiders, and that the ascending and moving 

 currents of air are entirely responsible for aeronautic phenomena. 



There appears to be a special tendency on the part of certain species 

 to undertake aeronautic flight, arid certain species appear to be destitute of 



1 Bulletin des Sciences Naturelles, October, 1829, page 133. 2 De Araneis, page 85. 



3 John Murray on the Aerial Spider, London Magazine of Natural History, November, 

 1828, pages 320, 324. 



