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when electricity plays upon it, there can be no doubt. 

 By the experiments of Barlocci of Rome, it appears 

 that the decomposed red and violet rays of the 

 spectrum are efficient in producing an electric effect. 



A spider's thread is an electric, and any such thread 

 projected through the air must necessarily become, 

 by such resistance as is occasioned by the atmosphere 

 and consequent friction, imbued with electricity. A 

 thread of glass is electrified under such circumstances, 

 and indeed Mr. W. Ritchie has proposed threads of 

 glass as pendants in his new balance of Torsion. 

 The current of air, or the sunbeam, is the primary 

 exciting cause ; and the electric character and condi- 

 tion of the thread are continued and preserved by the 

 continuous action of the electricity of the solar ray. 

 A cloud skreens the disc of the sun ; and the exciting 

 solar ray being thus intercepted, the buoyant cause 

 is withdrawn, and the spider descends, at least when 

 the entire electric energy is expended, though by the 

 propulsion of other threads ; and the temporary buoy- 

 ancy thus obtained from a partial evolution of elec- 

 tricity, the consequence of atmospheric friction, its 

 threads of attachment will then become a complete 

 parachute, and the rapid fall of the insect prevented. 

 We have made experiments and observations recently 

 to ascertain this point, and find that a thread detached 

 from the insect will receive electricity from the solar 

 ray, and ascend in the atmosphere in the sunbeam, 

 when without the sphere of attracting substances, 

 while a similar thread in the shade will not ascend at 

 all ; and we also find very light flocculi will also, having 

 absorbed electricity, ascend ; and if such should enter 

 the shade, they as immediately descend ; and we have 

 seen such in their descent brought by some casual 

 circumstance into the sunshine again, and as imme- 



