38 



able, we observed an extraordinary aura, or atmo- 

 sphere round the thread, which we cannot doubt was 

 electric. * 



We began our experiments and observations on this 

 curious subject on the 2d of June, 1822: one of these 

 spiders alighted on us, and glanced off from the hand 

 with considerable rapidity: thermometer 77 in the 

 shade. It is impossible to walk in the fields without 

 being saluted by several of these insects : they will be 

 chiefly noticed by alighting on the hat, and descending 

 by a thread before the face: in this way they are 

 easily caught, as they will drop into a chip-box, and 

 may be secured. When swinging from a support, they 

 will soon be perceived to ascend from the perpendi- 

 cular into the horizontal plane, at each ascent project- 

 ing a thread into the atmosphere ; and at length the 

 insect breaks from its anchorage, and ascends. Some- 

 times aeronautic spiders will take their flight imme- 

 diately from the surface on which they alight, if the 

 day be warm and sultry : but they generally descend 

 to from 6 to 18 inches, perhaps the better to insulate 

 themselves, and that, suspended by a pliant thread in 

 free space, they may more freely propel their threads 

 into the atmosphere. Not unfrequently the propulsion 

 of a solitary thread will bear them aloft ; but the air 

 must then be very warm, the sunshine bright, and 

 the electric character of the atmosphere considerable. 

 Sometimes the ascent is so rapid that the eye cannot 

 trace it ; at other times slow and majestic. Occasionally 

 the ascent is quite vertical, and at other times the in- 

 sect sails on the bosom of the air, either in the hori- 

 zontal plane, or at angles more or less open. It will be 

 also found that there are particular seasons of the year 

 best calculated for this singular exhibition : spring and 



* A similar phenomenon appears to have beeen witnessed by 

 " Carolan," and recorded in the Annals of Philosophy. 



