PROTECTION AGAINST LIGHTNING. 689 



was established by this threefold distribution amounted altogether to 

 333,000 square yards of conducting communication. Iron rods were 

 used in preference to copper in this construction on account of the 

 cost which would have been entailed if copper had been employed for 

 so extensive a work, and also because Professor Melsens had satisfied 

 himself that iron has more tenacity and power of cohesion than cop- 

 per when exposed to the disintegrating strain of powerful discharges 

 of electricity. He devised a very pretty experimental proof of this, 

 in which the discharge of a large battery of Leyden-jars was passed 

 through a fine wire of equal dimensions throughout, but of which one 

 half was composed of copper and the other half of iron. The iron 

 portion was converted into a beaded, but still unbroken, strand by the 

 discharge, but the copper part was scattered into a black impalpable 

 powder. It is scarcely too much to say that the Hotel de Ville at 

 Brussels at the present day, with its lofty aigrette-defended tower, its 

 forest of points, its net- work of rods, and its widely ramifying earth- 

 roots, is, as far as danger from lightning is concerned, one of the best 

 protected buildings in the world. It may safely be affirmed that it is 

 quite as hard for the lightning to get mischievously at this building, 

 as it is for the discharge of the Leyden battery to get at Professor 

 Melsens's birds when they are inclosed in their iron cage.* In the 

 heaviest of storms Professor Melsens travels about within the meshes 

 of his system of conductors, to investigate their behavior, with the 

 most perfect sang-froid and confidence. In 1866 Professor Melsens 

 examined with great care the transmitting capacity of his system of 

 conductors at the Hotel de Yille, and in this final investigation he em- 

 ployed all the various means that are now at the command of science. 

 He used continuous currents, instantaneous discharges, sparks from 

 the electrical machine, from powerful batteries, and from a large 

 Ruhmkorff coil, and with all he found that the conductibility of his 

 system was practically perfect. 



One of the grbunds upon which Professor Melsens adopts his sys- 

 tem of multiple rods is the circumstance that an electrical discharge 

 diffuses itself through all the branches of a multifold conductor in 

 proportion to the resistance which is offered by each part, and that it 

 does not all concentrate itself into the shortest and most open path. 

 He has devised some very ingenious experiments for proving this po- 

 sition, and has been able to show the sixty-thousandth part of a dis- 

 charge passing by a very narrow and roundabout path, when a broad 

 and direct one was open, and traversed by the larger proportions of 

 the discharge. He brought this part of his subject under the notice 

 of the Academy of Sciences of Belgium in a special liote, which was 

 printed in their " Bulletins " in 1875. — Edinburgh Beview. 



* M. de Fonvielle says of this plan of defense that Professor Melsens does not leave 

 the lightning a gap that it can get through, 

 vol.. XXV. — 44 



