There is one subject in regard to the proper protection of buildings against the destructive effects of lightning which is generally overlooked, at least in this country, to a really surprising degree. It is the necessity that lightning conductors, once put up, should be regularly inspected, to see if they are in good order, so as to be really efficacious. That this is very rarely done, is one of the main reasons why accidents by lightning sometimes occur in places nominally protected by conductors. The neglect is the more astounding, as one would think that all intelligent persons, whose knowledge prompted them to see the wisdom of protection against lightning, would likewise come to the conclusion that the scientific apparatus set up to effect it required occasional repairs, such as the clocks in their houses and the buildings themselves. But such is very far from being the case. It is, perhaps, not too much to assert that at present not one in a thousand persons who have gone to the expense of protecting their houses by lightning conductors make the protection complete, at a merely nominal cost, by providing a regular--say, annual or bi-annual--inspection.
The causes which necessitate such inspection are numerous. In the first instance, there is the constantly acting influence of wind and weather upon those parts of the conductor which are above earth. Wonderful as is the simple machinery devised by Franklin which conducts the mysterious electric force from the clouds into the ground, depriving it of its destructive power, it is, after all, but a feeble thing in itself, and necessarily so. The upper terminal of the conductor--what the Germans call the ‘reception rod,’ and the French the ‘tige,’ or stem--cannot be very thick without becoming unsightly, and, as regards large public buildings, destroying their architectural effects; while the rope, or ribbon, running to the ground must, for the same reason, as well as that of cost, be of comparatively small diameter. Subject to the constant effects of moisture, to wind, and ice, and hailstorm, there is always a possibility of the slender metal strips being damaged, so as to interrupt their continuity, and thus destroy the free passage of the electric force. Instances have happened in which the damage done was so slight as to be scarcely visible, and still sufficient to destroy the efficacy of the conductor. Nothing but the regular testing by a galvanometer--one of which is described, with an illustration, on page 60--by an experienced person can establish the fact that the action of the conductor remains perfect.