On JVorih American Spiders. 119 



"Bennet and other electricians have long ago proved, that the im- 

 pulse of air on a delicate electroscope invested it with electricity ; 

 and this, if proved in the one case, must of necessity be admitted in 

 the other. In the Mediterranean, Mr. Black appears to have ascer- 

 tained that winds, or currents of vapor of some continuance, are 

 negatively electrical, and the land breeze in a state of positive elec- 

 tricity. It seems deducible, therefore, that an electrical excitement 

 may be the consequence of such currents ; and it seems equally ob- 

 vious that insects are sufficiently sensible to atmospherical electricity. 

 Thus Huber seems to have proved, that the secretion of honey is 

 intimately connected with electricity ; and that bees are far more 

 active and laborious before a storm, and when the wind is south and 

 the air warm and humid, than at other times: and Kirby and Spence 

 also observe, that ' insects seem particularly excited by a high elec- 

 tric state of the atmosphere, and are then found more numerous on 

 the wing than at ordinary periods, and towards evening ; and that, 

 some time before the storm comes on, various kinds may be then 

 seen, that do not appear at ordinary times: but immediately before 

 the storm, all disappear.'* D'Isjonval observes, that 'animals are 

 affected by natural electricity ; but no one more than myself and my 

 spiders.' He had found, by repeated observations, that the length of 

 the spiders' threads corresponded with the electrical state of the at- 

 mosphere : for in wet and stormy weather they were short, and in 

 fine weather were proportionably long. Now, as there may exist 

 other causes sufficiently powerful to act as excitants, as well as a cur- 

 rent of air, the question remains as it was : besides, apart from an 

 effect analogous to electrical excitement, the modus operandi of a 

 current of air seems most obsure and perplexing." 



" Gay Lussac considers the ascent of clouds, in the regions of air, 

 entirely ascribable to the impulse of ascending currents, arising from 

 the difference of temperature between the surface of the earth and 

 the atmosphere at great elevations." "But the fact proves that 

 clouds are replenished with electricity, and the sunbeam which im- 

 pinges on them may be the medium of supply." "When the gossa- 

 mer tissue is woven on some aerial plane, its continued buoyancy is 

 no more unaccountable than the floatage of the clouds, if the opera- 

 tive causes be similar : and as the ' cloud of night' sinks upon the 

 plain, so does the gossamer spider revisit the earth ; and as clouds 



* The extraordinary activity of the swallow on these occasions is a manliest proof. 



