49 



all. The cause of the ascent follows : " The ascending 

 current occasioned by the rarefaction of air contiguous 

 to the heated ground, acted with so much force as to 

 separate them from the objects to which they were 

 attached, raising them in the atmosphere to a perpen- 

 dicular height of at least several hundred feet ! " 

 This refers to the ascent of " masses of considerable 

 magnitude," formed by " the mechanical action of 

 gentle airs," i. e. " the lines of which they were com- 

 posed." These tumbled down again " in the after- 

 noon, when the upward current had ceased," but 

 " scarcely one in twenty," says Mr. Blackwall, " con- 

 tained a spider." This is the only record, we believe, 

 of an ascent ; but the descent of cobwebs from the 

 aerial regions we, in common with numbers, have 

 observed, and believe it is a phenomenon much less 

 common during the months of September and Octo- 

 ber than may be generally credited. It does not 

 appear that Mr. Rennie has observed any thing of this 

 kind, nor does he follow out Mr. Blackwall in his 

 hypothesis here, or say any thing about the cause of 

 the ascent: " blowing obliquely upon them," " blowing 

 towards it," and " blowing out," &c. seem to have sup- 

 plied sufficient exercise without such research. It is not 

 doubted by any one that the gossamer spider can pro- 

 ject into the air a multiplicity of threads when swing- 

 ing from a point ; and it is unreasonable therefore 

 surely to deny the power of doing so to these insects 

 when careering aloft on their silken parachutes, and 

 " sailing on the bosom of the air." When the gossamer 

 tissue is woven on some aerial plane, its continued 

 buoyancy is no more unaccountable than the floatage 

 of the clouds, if the operative causes be similar : and 

 as the " cloud of night " sinks upon the plain, so 

 does the gossamer spider revisit the earth ; and as 

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