346 Barns often struck by lightning, 



necessary to enter on the proof of the fact, which will there- 

 fore be taken for granted. — What then is the cause? 



It will be observed, that these events more generally oc- 

 cur after harvest, or hay-time, when the barns are more or 

 less filled with hay and grain ;* which renders the calamity 

 peculiarly distressing, as, in many instances, the farmers' 

 hopes are blasted in an hour. 



It is obvious, that the produce of the fields, when stored 

 in a barn, must give rise to a copious evaporation. This is 

 peculiarly the case with hay, which, especially when put up 

 still damp, (and it always is so in a degree,) sweats (as it is 

 termed) very powerfully ; a hand thrust into the mow, is 

 often rendered sensible of great heat and moisture, and a 

 visible vapour is often abundantly exhaled, when a heap of 

 such hay is moved. As the large barns of the farmers often 

 contain many tons of hay and grain, it is obvious, that this 

 cause is sufficient to produce the rise of a great column of 

 vapour into tlie atmosphere, and that may be the fact for 

 weeks together. 



Vapour is a good conductor of the electric fluid; and thus 

 the lightning may be determined, by the attraction of the va- 

 pour, to descend upon the barn, rather than to strike at random. 



There is an additional fact, which is worthy of being men- 

 tioned. Evaporation, viz. the very act of forming vapour, 

 produces electrical excitement ; the vapour itself is differ- 

 ently electrified from the bodies around, and to produce a dis- 

 charge of the electric fluid, it is necessary only that there be 

 a decidedly different electrical state between two contiguous 

 bodies ; as, for instance, between the vapour arising from 

 the barn and the neighbouring thunder cloud. It is imma- 

 terial which is positively, and which negatively electrified. f 



Both these causes then, — that is, the conducting power of 

 the vapour, and its different electrical state, may conspire to 

 direct the lightning where to strike; and, from the combusti- 

 ble nature of the usual contentsofbarns,aswellas of the build- 

 ings themselves, it is in no way surprising that, when struck, 

 they are almost inevitably consumed. The most interesting 

 question remains — What can be done to remedy the evil.^ 



* Cor7i, in the language of the English farmers. 



t The electrical excitement, produced by evaporation, is seen in the fa- 

 miliar experiment of putting a few live coals into a crucible; the crucible 

 is placed on the cap of the gold leaf electrometer, and water is dropped upon 

 the coals, when the gold leave? of the electrometer in?tautly diverge. 



