Preventive Measures against Lightning. 185 



chamber. When this suspension cannot be obtained, it is ex- 

 pedient to interpose between one's self, and the floor, some of 

 those bodies which the fulminating matter traverses with the 

 greatest difficulty. Accordingly, a chair may be placed on 

 glass, or pitch, or on mattresses. These precautions have a 

 direct tendency to diminish the danger, but they do not wholly 

 remove it. In fact, there are examples, of glass, pitch, and 

 many and thick mattresses having b^en traversed by lightning. 

 Besides, it ought not to be forgotten, that if the lightning does 

 not encounter, in the chamber, a wire-bell, which will lead 

 it out, it may dart from one point to another diametrically op- 

 posite, and in its course, may strike individuals in the centre, 

 and even suspended in their hammocks. 



Meteorologists, and among others M. Balitoro, assert, that 

 lightning never strikes buildings upon their northern fronts ; 

 and according to them, it is on south-east exposures that it is most 

 of all to be dreaded. This opinion, it is stated, is so generally pre- 

 valent in Italy, that during a thunder-storm, many people take 

 the precaution of seeking refuge in those chambers of their house 

 which have a northern exposure. If this observation be truly 

 accurate, it is probably a consequence of the direction according 

 to which, in our climates, the wind almost always blows during a 

 thunder-storm. Clouds coming from the ^om^^, and highly im- 

 pregnated with fulminating matter, can scarcely fail to part with 

 it in preference, on*the first front of the edifices they encounter. 

 Besides, since it has been estabhshed, that the highly elevated 

 jets of the aurora-borealis range themselves in a direction paral- 

 lel to the inclination of the magnetic needle, we have no right to 

 deny the possibility of a similar, or common direction, to ful- 

 minating rays. 



According to Nollet, the height and, all other circumstances 

 being equal, the roofs of those belfries which are covered with 

 slates, are more frequently severely injured by lightning than 

 such as are built of stone. We are not, I imagine, to look for 

 the cause of this peculiarity in any specific difference of the ma- 

 terial of which slate and the stones in question are composed. 

 It seems to be dependent rather upon the facility with which 

 during rain, the wood- work, and more especially the planks on 



