PROTECTION FROM LIGHTNING. 



107 5 



provided with paratonnerres similar in principle to those of Franklin ! The 

 roof of the building was formed of cedar, covered with thick gilding, and from 

 end to end was adorned by a row of long lances of iron or steel, pointed and 

 gilt. According to Josephus, the architect intended these numerous points 

 to prevent birds from defiling the roof. The several fronts of the building 

 were constructed throughout their whole extent of wood thickly gilt. Finally, 

 under the porch were cisterns, into which the waters of the roof were dis- 

 charged through metallic pipes provided for that purpose. It appears, there- 

 fore, that the roof was protected by a vast number of pointed metallic rods 

 communicating with a superabundance of metallic conductors, which were con- 

 tinued to cisterns of water below, so that the most carefully-constructed para- 

 tonnerres of the present day could not confer greater security. 



The church of the chateau of Count Orsini, in Carinthia, standing on an em- 

 inence, was so often struck by lightning, and so many fatalities occurred in 

 consequence, that, at length, the celebration of divine service was discontinued 

 there in summer. In the course of the year 1730 the steeple was entirely de- 

 stroyed by lightning. After it was reconstructed, it continued to be struck four 

 or five times a year. In 1778 it was entirely demolished, and being immedi- 

 ately rebuilt, it was now supplied with a paratonnerre. From that time the 

 building was free from damage by lightning. In five years it was struck but 

 once, and then the fluid was conducted to the earth by the paratonnerre, with- 

 out injury to the church. 



In 1750 and 1763 the Dutch church at New- York was struck by lightning, 

 and sustained great injury. It was after that provided with a paratonnerre, 

 and, being again struck in 1765, sustained no injury. 



The church of St. Michael, at Charleston, used to be struck and damaged 

 once at least in two or three years. It was provided with a paratonnerre, after 

 which it sustained no damage. 



Before the time of Beccaria, the palace of Valentino, at Turin, was con- 

 stantly struck by lightning and damaged. Beccaria erected paratonnerres upon 

 it, and the damage ceased. 



The tower of St. Mark, at Venice, was, until the year 1776, constantly struck 

 by lightning, and sustained occasionally great damage. In that year a para- 

 tonnerre was placed upon it, and no damage has occurred since. 



Mr. Snow Harris states that, of six steeples in Devonshire, all hav been 

 within a short period struck by lightning. One only sustained no damage, and 

 that one alone was provided with a paratonnerre. 



The present lecture would be incomplete, were we to close it without advert- 

 ing to the phenomena termed " the lateral discharge ;" it bears intimately on 

 the practical part of the subject, and will enable us at the same time to present 

 certain illustrations 'of the action of electricity which have not been included 

 elsewhere. When a portion of the discharge from a prime conductor, for in- 

 stance, or a Leyden jar, leaves the course marked out for it to pursue a side- 

 path, the spark consequent on such deviation is termed the lateral spark ; it is, 

 in fact, a spark produced by the division of the discharge. It may be shown 

 in the following manner : Let a powerful electrical machine be in action, and 

 sparks be thrown on a wire held by an insulated rod, but having its extremity 

 connected with the earth ; on applying the knuckle, or a brass ball, to any part 

 of this wire, sparks may be obtained ; not that the wire is incapable of carrying 

 away the whole charge safely, but because of the repulsive action of the elec- 

 tricity, by which it has a tendency to spread over the surface of conductors, 

 and take the widest path it can. The tendency is even developed when the 

 side-path only lasts for a part of the course to the earth, and the electricity has 

 to return again to its original wire, for, if the insulated discharging-rod have 



