47 



air." But they seem " noticeable" beings, as Words- 

 worth would say ; for Mr. Rennie has actually seen 

 them " endeavouring to ascertain in what direction the 

 wind blew, or rather, which way any current of air 

 set, by elevating their arms, as we have seen sailors 

 do in a dead calm!" It certainly would be a matter 

 of difficulty to ascertain, " in a dead calm," what way 

 the wind blows, and we doubt whether even Maho- 

 met's spider could do this. We presume, at any rate, 

 that the property which spiders have of shooting out 

 their threads was much more early observed than is 

 generally supposed. " Spiders," saith Aristotle, " cast 

 their threads, not from within, as an excrement, as 

 Democritus would have it, but from without, as the 

 histrix doth its quills." * 



The ascent of this apterous insect into the air is a 

 problem which very few have attempted to solve, and, 

 from the difficulty attendant upon it, many have de- 

 nied its possibility altogether. It seems to have 

 puzzled Mr. White a good deal : however, the following 

 supposition is hazarded : "I should imagine," says 

 he, " that those filmy threads, when first shot, might 

 be entangled in the rising dew, and so draw 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, then, when they become 

 heavier than the air, they must fall." 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 ele- 

 vations. Mr. Blackwall assumes the same impulsion, 



* Grew. 



