51 



cated as possible, else we could refer to numerous 

 electrical principles in proof of what we have en- 

 deavoured to substantiate ; our experiments are far 

 too numerous for complete and minute detail, and 

 their multiplicity might confuse and complicate rather 

 than simplify and elucidate : nor shall we presume to 

 state in illustration, any thing but what we feel confi- 

 dent that we have the warrant and evidence of our 

 senses for, and that too on frequent repetition; only ob- 

 serving in this place, that on the assumed principles of 

 heated currents, the following queries seem to us to 

 admit of no satisfactory solution. How does it happen 

 that the ascent of the bird spider is slow at one time, 

 and rapid as an electric flash at another ? vertical at 

 one period, and afterwards horizontal, or in variously 

 inclined planes ? on one day requiring the propulsion 

 of numerous threads, and the next a solitary one 

 affording buoyancy enough ? ascending at any period 

 of the day in one case, and on the following day inca- 

 pable of effecting an ascent at all, whether at morn, 

 noon, or night, even with multiplied threads, and 

 when calorific emanations are assumed to be operative? 

 In fact, that a single upright thread should carry 

 up the spider in the vertical plane, on any such princi- 

 ple, seems to us utterly incomprehensible. 



It may aid in the solution of the question pro- 

 pounded in these observations to premise, that when 

 at Rome in 1818. Signer Morrichini of that city in- 

 formed us he had found the rays of the solar spectrum 

 delicately electric; since that period, the electricity of 

 the solar ray has been more decidedly determined by 

 Savario Barlocci, and Carlo Mattrucci, of Forli. The 

 latter observed in his experiments, that a glass plate 

 never became electric when the disc of the sun was 

 obscured by clouds, and that a floating body will rise 

 D 2 



