To the three great causes before indicated which make the regular testing of conductors an almost imperative necessity, several minor ones may be added. Among them may be cited the frequency of repairs of the walls and roofs of houses. Our modern houses, as we all know, are not built, like those of the Romans, ‘for an eternity,’ but in the vast majority, particularly in towns, are ‘leaseholds for ninety-nine years.’ Many of them, perhaps, can scarcely be expected to last ninety-nine years, being constructed by their builders on the principle of Peter Pindar’s razors, ‘not to shave, but to sell.’ Hence the absolute necessity of repairs without end. Without casting the least slur upon the character of the artisans who execute these, bricklayers, plasterers, painters, plumbers, and others, it may be fairly asserted that they are densely ignorant as to the nature of lightning conductors. It is not at all a wonder that this should be so, since they share their ignorance with many persons of far higher education, who know no more of the action of the electric force in seeking its way from the clouds into moist earth than they do of that of a voltaic apparatus, or of a condensing steam-engine. These artisans, then, in whose hands the repairs of houses are left, naturally treat the narrow strip of metal running from the top of houses to the bottom with great indifference, not having the slightest idea of its being one of the most marvellous conceptions of the human mind. It has been reported, on good authority, that there are frequently workmen to be found, such as house painters and others, whose business it is to ‘decorate’ the outside of dwellings with the stuff called ‘stucco,’ who feel a sort of mild hatred for lightning conductors, as interfering with their achievements, and, as they think, disfiguring the beauties which they are creating. Woe to the poor conductor within their reach! Unless very conspicuously placed, which is rarely the case, the tenant of a house will seldom discover in time that the slender rope, or ribbon, which gives him and his family protection against lightning has been broken by cunning hands when the last repairs were effected, and the ends stowed away in the gutter on the roof. The discovery will be made, in the absence of inspection, probably, only under the fierce light of a flash of lightning from a passing thunderstorm.