118 On North American Spiders. 



" Several circumstances concur to show the phenomenon of ascent 

 to be electric: the propelled threads do not interfere with each other; 

 they are divellent, and this divergence seems to proceed from their 

 being imbued with similar electricity 5 and the character of that elec- 

 tricity appeared to us to be an interesting subject for subsequent re- 

 search. When a conductor is brought near the thread by which it 

 suspends itself, but, above all, to the floccuU or balls, they are con- 

 siderably deflected from the perpendicular, and the horizontal fibre 

 is attracted by the point : when a stick of excited sealing-wax was 

 brought near the thread of suspension, it seemed to be repelled; 

 consequently the electricity of the thread is negative. The descent 

 of the thread is instantly determined by bringing over it the excited 

 sealing-wax. On the 3d of July, 1822, at 4 P. M., thermometer 

 66° F., when two aeronautic spiders, on separate threads, were 

 brought near to each other, a mutual repulsion supervened. 



"In one experiment made, the ascent of the insect was so slow 

 and tranquil, from the humidity of the lower atmosphere and wet- 

 ness of the terrestrial surface, that I could easily catch it by follow- 

 ing its progress : it moved in a plane parallel to the point of departure. 

 On the 4th of August, 1822, at 3 P.M., thermometer 66°, the as- 

 cent was slow and beautiful, the little aeronaut rising regularly in the 

 vertical plane. It was distinctly perceived, from the steady fixation 

 of the eye and favorable angle of vision, until it had attained an ele- 

 vation of at least thirty feet, and was finally lost in the vanishing point 

 of elevation. 



"A variety of phenomena unite their testimony in favor of the con- 

 clusions formed, and from what we consider the direct method of in- 

 duction. Were the thread not electrical, we may be asked how it 

 could be propelled through the atmosphere in the vertical plane, and 

 remain there, contrary to the laws of gravitation ? It is indeed re- 

 markable, that the threads should always remain in the precise plane 

 in which they, are propelled, nor swerve from it. The constant rela- 

 tive separation finds an analogy in similarly electrified pith-balls, or 

 the divergence of the filaments in a glass plume, placed on the con- 

 ductor of an excited electrical machine, and the electric state of the 

 atmosphere will always be found to modify the phenomena. The 

 transit of the thread through a resisting medium, without its suffering 

 deflection in its path, seems to prove it imbued with a power supe- 

 rior to, and able to overcome, that resistance." 



