THE AERIAL SPIDER.
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The cobwsbs which are found occasion ally floating in the air, alighting on the face and person as we walk, in threads of finest texture, and which are observable more especially in dewy mornings, at cer- tain seasons, overspreading the fields with :s. nhars .e- sS;dsrs. wb;esr b;sr.fs dss= scended during the night to imbibe the moisture, weave among the blades of grass, the webs which collect the dew. The cause of the rising of this insect and it's web into the air, since its specific gravity considerably exceeds that of the atmos-

 phere, has been variously explained. MT.

 Blackwell, in an address to the Linnean

 Society, proiesses to account for the ascent of the threads by ascribing t to the effect ot warm currents of air emanal,ng from the surface ofthe ground. MT. John Murray combats this doctrine, and accounts for the phenomenon in these floating webs on cleo trical principles. The following is the substance of his observations on this inter- es,ing insect, in the " Magazine of Natural History" of November last. During the day these aerial spiders, according to the electrical state of the atmosphere, either rise in vertical direction, and that rapid ly or slowly, as they are affected by some electrical circumstances) or they float at angles more or less inclined to the horizon, or on a paralled with its plane. They have the power of propelling their threads in similar variety of directions either in mo- tionless air, or in an atmosphere agltated by the wind, the threads preserving lnva- riably the direction in which they are pro- pelled. and never intermingling {; and sometimes pencil of threads presenting the appearance of a divergent brush is pro- pelled. On comparing these operations of the insect with the electrical state of the atmosphere, the following corresponding results are observable :-when the air is

 in a positive state, as in clear and fine

 weather, the spider makes his ascent more easily and rapidly; when it IS weakly pos,

 tive he rises with difficulty, to limited

 altitude, and with but slight inclination O

 the propelled threads above the plane O

 the horizon; while, when the negative G.

 lectricity prevails, as in cloudy weather

 or on the approach of rain. he is aItogethe

 unable to ascend; so also, as, towards

 evening, the positive electricity of th'

 air becomes feeble, aud during the nigh changes to negative, then the spiders de- scend to the earth. With regard to thu

 habits of this little aeronaut in other re

 spects, Mr. Murray says' he IS greedy Q

 moisture, though otherwise abstem'ons IL food is perhaps peculiar, and only ioan' in the superior regions of the sky; hk the rest ofi,s tribe, it is doubtless ca. n'vor ous, and may observe some highly 'mpor 2 tant purpose in the economy oi provI !, dence; such, flor instance, ,as the Gesuucuo' of that truly formidable, ,thoug h almost mlc nc

 roscopically minute insect the FIrla ln . ternalis, whose wound is stated to pc nor fal. Its existence has been, indeed' qGes toned, but by no means disProved thai and some others, injurious to man. or the inferior creation, may be its deStine

 prey, and thus our little aerOnaut, uRheed

 ed by the common eye, may suDserve a important gOod.-Mag. cf Nat. Hist.