What the writer says on the inspection of conductors is particularly worth quoting. ‘A lightning conductor,’ he remarks, ‘however excellent in the first instance, may lose all its good qualities, for several reasons. In the first instance it may suffer, like all mundane things, from age. The decrepitude will come on all the sooner whenever the materials are not of the best kind, or whenever little care has been taken in properly connecting the various parts. This is frequently the case in conductors of old design. But, even if all has been done that scientific skill can accomplish, age will make itself felt some time or other. Oxidation will play its part; so will the warfare of the elements. However safely secured at first, the attachment of the parts to the buildings will get loose, or perhaps even broken. Repairs consequently become indispensable. When are they to be effected? It can only be indicated by testing the conductor from time to time.’ Dr. Holtz next dwells at some length on the necessity of conductors being designed by thoroughly competent persons; not mere ‘lightning rod men,’ who are able to take into account all the particulars of the building which is to be protected, more especially the metal employed in the construction. ‘A conductor,’ he truly remarks, ‘cannot be expected to be a trustworthy protection against the destructive force of lightning, if simply set up over a house without consideration of its outer and inner features. Perhaps in buildings of olden times, into the construction of which metals seldom or never entered, a simple wire running from top to bottom, surmounted by an iron rod, was quite sufficient, but this is no longer the case, all the circumstances having been completely altered. The wire, however thin, was not merely the best, but the only path for the electric force. But at present the masses of metal used in the construction of buildings constitute a number of rival paths, and it requires very careful consideration indeed to lay down an absolutely infallible lightning conductor in such a way as to overcome all influences opposing its action. Therefore conductors of old construction can not only not be expected to be efficacious under modern exigencies, but even those made at the present time cannot be expected to be efficient under circumstances which, probably, the future may bring forth. There is really nothing else to make a lightning conductor a safe protection under all circumstances, and at all times, but regular, constant, and skilful examination.’