688 THE POPULAR SCIENCE MONTHLY. 



■vnthout the remotest chance that they would ever be touched by the 

 terrific discharges that were flashed through the walls of their prison- 

 cell in such close propinquity to them. What happened in the case of 

 the birds in this experiment assuredly would happen also in the case 

 of any building that was encaged in metallic rods in a similar way. 

 No demonstration of a mere physical fact could possibly be more abso- 

 lute or more complete. 



The Hotel de Ville at Brussels is a large mediseval building, inclos- 

 ing in its center an open quadrangular court, and surmounted in the 

 middle of its principal face by an elaborately pinnacled tower, 297 

 feet high, with a gilt statue of St. Michael at the top, standing upon 

 a prostrate dragon and flourishing a drawn sword above his head. 

 There are four galleries on the spire beneath the statue, and there are 

 also six spire-crowned subordinate turrets, and three parapeted gables 

 projecting above the roof from other parts of the building. The 

 statue of the saint is reared upon a lead-covered cupola or platform, 

 and Professor Melsens determined that the point of its sword should 

 serve as the culminant point of his system of lightning-rods ; but he 

 also took the precaution of very largely re-enforcing this highest termi- 

 nal by surrounding the base of the lead-covered platform at the feet 

 of the statue with a cJievaux-de-frise of outwardly and upwardly 

 branching rods, constituting a radiant circle of tufted points or 

 aigrettes. There were altogether forty-eight of these points project- 

 ing round the feet of the statue to a distance of eight feet in all direc- 

 tions. From these radiating aigrettes, and from the statue standing 

 above, a series of eight iron rods were carried down along the face of 

 the tower and the slope of the roof, through an entire length of 310 

 feet, to the interior court-yard. But as these rods descended along the 

 perpendicular face of the building they were joined by other similar 

 rods from the various subordinate turrets, pinnacles, gables, and ridges, 

 which all had their own systems of terminal points rising up toward 

 the sky. There were altogether 426 points projecting up from the 

 building. An observer looking down from one of the elevated gal- 

 leries of the spire took in at a glance quite a little forest of spikes 

 bristling up into the air, which were all in direct metallic contact with 

 the main stems of the conductors. 



An even more ample provision was made for the connection of this 

 system of conductors with the ground. The vertical rods were first 

 collected into an iron box fixed about a yard above the ground in the 

 inner court, and filled with molten zinc so as to unite the whole into 

 one continuous block of metal. From the hollow of this box twenty- 

 four iron rods, two fifths of an inch in diameter, issued, and of these 

 a third part was carried to an iron cylinder sunk in a well, another 

 third was connected with the iron water-mains of the town, and the 

 remaining third was put into communication in a similar way with the 

 gas-mains. Professor Melsens estimated that the earth contact which 



