SPIDERS. 3 17 



lines had become firmly attached to any object or 

 not, by pulling at them with the first pair of legs ; 

 and if the result was satisfactory, after tightening 

 them sufficiently, they made them pass to the twig ; 

 then discharging from their spinners, which they ap- 

 plied to the spot where they stood, a little more of 

 their liquid gum, and committing themselves to these 

 bridges of their own constructing, they passed over 

 them in safety, drawing a second line after them as 

 a security in case the first gave way, and so effected 

 their escape. 



" Such was invariably the result when spiders 

 were placed where the air was liable to be sensibly 

 agitated; I resolved, therefore, to put a bell-glass 

 over them ; and in this situation they remained 

 seventeen days, evidently unable to produce a single 

 line by which they could quit the branch they occu- 

 pied, without encountering the water at its base; 

 though, on the removal of the glass, they regained 

 their liberty with as much celerity as in the instances 

 already recorded. 



" This experiment, which from want of due pre- 

 caution has misled so many distinguished naturalists, 

 I have tried with several geometric spiders, and 

 always with the same success."* 



Mr. Blackwall, from subsequent experiments, says 

 he is " confident in affirming, that in motionless air 

 spiders have not the power of darting their threads 

 even through the space of half an inch."t The fol- 

 lowing details are given in confirmation of this 

 opinion. Mr. Blackwall observed, the 1st Oct., 1826, 

 a little before noon, with the sun shining brightly, 

 no wind stirring, and the thermometer in the shade 

 ranging from 55° 5 to 64°, a profusion of shining 

 lines crossing each other at every angle, forming a 



« Linn. Trans., vol. xv. p. 456. 

 f Mag. Nat. Hist, vol. ii. p. 397. 



