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mettions a nier tout ce qu'on ne sait pas expliquer ? " The amount of trustworthy and 

 independent evidence which we possess as to the occurrence of this phenomenon is 

 such as must convince every reasonable man who chooses to pay due attention to 

 the subject. No doubt there is a great deal of exaggeration, as well as much 

 imperfect and even erroneous observation, in almost all of these records. But the 

 existence of the main feature (the fire-ball) seems to be proved beyond all doubt. 



The most marked peculiarities of this species of lightning-discharge are its com- 

 paratively long duration and its comparatively slow motion. While a spark, or 

 lightning flash, does not last longer than about a millionth part of a second, if so 

 long, globe-lightning lasts from one to ten seconds, sometimes even longer, so that 

 a sufficiently self-possessed spectator has time carefully to watch its behaviour. The 

 general appearance is that of a luminous ball, which must be approximately spherical, 

 because it always appears circular in outline, slowly and steadily descending from a 

 thundercloud to the ground. It bursts with a loud explosion, sometimes before 

 reaching the ground, sometimes as it impinges, and sometimes after actually rebound- 

 ing. Its size varies from that of a child's head to a sphere of little less than a yard 

 in diameter. On some occasions veritable flashes of lightning were seen to proceed 

 from large fire-balls as they burst. It is difficult to imagine what these balls can 

 be if they be not a species of natural Leyden jar very highly charged. If it be so, 

 no ordinary lightning-rod can possibly prevent danger from it ; and we may thus 

 be able to explain the very few cases in which damage has been done by lightning 

 to thoroughly protected buildings. To guard against this form nothing short of a 

 pretty close net-work of stout copper wires would suffice. Meanwhile I give a 

 brief sketch of two out of the long series of descriptions of such phenomena which 

 Arago has patiently collected. The first is given on the authority of Babinet, who 

 was deputed by the Academy of Sciences to make inquiries into the case. 



Shortly, but not immediately, after a loud peal of thunder, a tailor who was 

 sitting at his dinner saw the paper ornament which covered his fire-place blown 

 down as if by a gentle breeze, and a globe of fire, about the size of a child's head, 

 came gently out and moved slowly about at a slight elevation above the floor. It 

 appeared bright rather than hot, and he felt no sensation of warmth. It approached 

 him like a little kitten which desired to rub itself in play against his legs ; but he 

 drew his feet away, and by slow and cautious movements avoided contact with it. 

 It remained several seconds near his feet, while he leaned forward, and carefully 

 examined it. At last it rose vertically to about the level of his head, so he threw 

 himself back in his chair and continued to watch it. It then became slightly 

 elongated, and moved obliquely towards a hole pierced to the chimney about a 

 yard above the mantel piece. This hole had been made for the chimney of a 

 stove which was used in winter. " But," as the tailor said, " the globe could not 

 see the hole, for paper had been pasted over it." The globe went straight for the 

 hole, tore off the paper, and went up the chimney. After the lapse of time which 

 at the rate at which he had seen it moving, it would have required to get to the 

 top of the chimney, a terrific explosion was heard, and a great deal of damage was 

 done to the chimney and the roofs around it. 



The next is even more striking: In June, 1849, in the evening of one of the 



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