On Ascending Lightning. Ill 



The minute discussion, which occupied us in another part of 

 this essay, concerning the transportation of ponderable sub- 

 stances produced by lightning, demonstrates that these curious 

 phenomena can be explained without having recourse to any 

 pretended nexv principles of natural philosophy. This other 

 result may be also drawn from it, viz. that we cannot deduce 

 from the direction of the transportation produced by the light- 

 ning, the direction of the course of the meteor itself; and that 

 the researches of those, who, supporting their opinions on a 

 similar basis, have discussed the phenomenon oi ascending light' 

 ning, had no good ground for their views. The question is so 

 important as to demand development. 



Certain natural philosophers, as we have already explained, 

 make lightning to consist in a subtile matter, which darts with 

 the greatest rapidity from the body containing the lightning 

 to the body struck by it, whilst others regard it only as a vi- 

 bration. But, whichsoever of these hypotheses is adopted, the 

 direction of the propagation of the lightning, — in other words, 

 the direction of the propagation of the subtile matter, or of 

 the vibration, has hitherto been regarded as coinciding with that 

 of the mechanical effects produced by the matter, or by the im- 

 pulsion of the fluid. The lightning, it is alleged, which darts 

 from above downwards, should properly be called descending 

 lightning ; and, on the contrary, the name ascending lightning 

 should be appropriated to that which projects from below up- 

 wards, the substances it encounters in its course. Hence there 

 should also occur, if such there be, oblique and lateral light- 

 nings, in all directions. Facts which would go to the sup- 

 port of such distinctions are by no means rare, and we shall 

 now cite a few. On the 24th of February in the year 1774, 

 lightning struck the steeple of the village of Rouvroi, to the 

 north-west of Arras. One of its effects was the upraising of 



ice, when it tears the capillary tubes which fonu the succulent twigs of cer- 

 tain plants. At the same time, as the aqueous juices dilate much more in pas- 

 sing from the liquid state to that of steam than they do in congealing, the me- 

 teor ought to produce more numerous and also more violent ruptures. By 

 taking this view of the phenomenon, physiologists will perlJaps be enabled to 

 recognise the particular mode of action by which lightning produces death 

 in the more common way. 



