312 Notices respecting New Books. 



the building, but leaving the lower portions and general mass of 

 the building unprotected, or (2) of supplying all, even the lower 

 portions of the edifice, with conductors of lesser height and dimen- 

 sions, but all connected among themselves, and all leading finally 

 to some great conducting mass of earth or water into which the 

 electric discharge should finally find issue. M. Melsens was led to 

 conclude decidedly in favour of the latter plan, and to adopt in 

 electricity, as is often done in public matters, the maxim divide et 

 imjoera. He was struck with the fact that, although dating from 

 1400, the Hotel de Yille had never been struck by lightning 

 until the present century, and has since been struck several times, 

 although seriously damaged only on the last occasion, in 1863. He 

 attributes this remarkable immunity of four centuries to the amount 

 of gilding and metallic decoration &c, which almost covered over 

 the surface of the building in the later middle ages and down to 

 the end of the last century — the projecting pinnacles and statues 

 especially having been then blazing with gold and brass, thus fur- 

 nishing an enormously extended, if superficial, issue for the electric 

 discharge. On the other hand, in the case of the last thunder-storm 

 he finds the greatest injury to have occurred where parts of the 

 towers and pinnacles were supported by iron bars which were un- 

 connected with each other or with the ground. Where perfect 

 connexion existed, even, as in the case of the great clock, by a few 

 thin wires, the electric discharge passed harmlessly along ; and the 

 fortunate escape of the great central spire from destruction is thus 

 to be accounted for. 



Acting on those principles, M. Melsens devised an arrangement 

 for investing the Hotel de Ville with a connected series of conduc- 

 tors moderate in mass and in height, terminating on each projecting 

 eminence of the building in pencils of wire, but not prominently 

 interfering with the architectural characteristics. In this way the 

 edifice is surrounded by a complete cage of iron wire, so that a flash 

 of lightning striking on any point must be immediately subdivided 

 into a multitude of parts and so diluted as to be rendered innocuous. 

 This iron cage is in its turn connected with what M. Melsens terms 

 the subterraneous paratonnerres, consisting of the whole system of 

 pipes employed in the gas- and water- distribution of the city ; and, 

 from the details of the mechanical arrangements given, this con- 

 nexion is of the most perfect kind. On this point M. Melsens 

 lays considerable stress, as he believes that very many lightning- 

 conductors of the ordinary kind are rendered useless practically by 

 the imperfect connexion with a sufficient mass of earth and water 

 conductor. We must refer to the work itself for all the mechanical 

 details by which M. Melsens's ideas have been practically carried 

 out, and which are copiously illustrated by engravings. We shall 

 not either enter into the discussion as to the merits of the questions 

 still at issue among practical electricians of great eminence and ex- 

 perience. M. Melsens gives in his book a full and fairly stated 

 resume of the arguments and evidence against as well as in favour 

 of his own views ; and that his views, even when deviating from 

 the traditional decisions of scientific authorities (as, for example, of 



