less than this rule would indicate, rather than more. Indeed, we 

 see no objection to an indefinite multiplication of rods to a house, 

 provided they are all properly connected with the ground and wilh 

 each other. A building entirely inclosed, as it were, in a case of 

 iron rods so connected with the earth, would be safe from the direct 

 action of the lightning. 



10th. When a house is covered by a metallic roof, the latter 

 should be united, in good metallic connection, with the lightning 

 rods ; and in this case the perpendicular pipes conveying the water 

 from the gutters at the eaves may be made to act the part of rods, 

 by soldering strips of coi^per to the metal roof and pipes above, 

 and connecting them with the earth by plates of metal united by 

 similar strips of copper to their lower ends; or, better, with the 

 gas or water-pipes of the city. In this case, however, the chimneys 

 would be unprotected, and copper lightning-rods soldered to the 

 roof and risinir a few feet above the chimneys, would suffice to re- 

 ceive the disch^arge. We say soldered to the roof, because, if the 

 contact was not very perfect, a greater intensity of action would 

 take place at this point, and the metal might be burnt through by 

 the discharge, particularly if it were thin. 



nth. As a general rule, large masses of metal within the build- 

 ino- particularly those which have perpendicular elevation, ought 

 to°be connected with the rod. The main portion of the great 

 building erected for the World's Exhibition at Paris was entirely 

 surrounded by a rod of iron, from which rose at intervals a series 

 of lightning-conductors, the whole system being connected with the 

 earth by means of four wells, one at each corner of the edifice. 



The foregoing rules may serve as general guides for the erection 

 of lightning-rods on ordinary buildings, but for the protection of 

 a large complex structure, consisting of several parts, a specia 

 survey should be made, and the best form of protection devised 

 which the peculiar circumstances of the case will admit. 



