Page:Popular Science Monthly Volume 25.djvu/834

816 to do away altogether with the lightning-rod as a dangerous and superfluous expedient, and to establish in its place a system of earth-buried plates and short earth-points surrounding the building. Space does not here permit an allusion to the various fallacies which are involved in this heretical scheme. It will be enough for all practical purposes to say that the proper answer to the dangerous heresy is an appeal to the argument of facts. There are innumerable instances on record in which lightning has been seen to strike lightning-conductors with a luminous flash, and there are still more in which the extremity of the rod bears the traces of the passage through it of lightning; but in every case, if the rod has been of due size and properly constructed and fixed, the building associated with it has been entirely uninjured. The truth obviously is that the question of efficiency and safety entirely hangs upon the amplitude of the dimensions, the number and position of the points, and the completeness of the earth contact, of conductors. In any case where these are insufficient the lightning-rod is a source of danger. In every case where they are ample, and where the system of their establishment is sound, the protection is complete. It will be time enough to enter upon a consideration of the merits of the retrograde course which is advocated in this ill-advised scheme when any single case of failure in a lightning-conductor of satisfactory dimensions, and of tested perfection of construction, has been established before a competent jury on incontrovertible grounds. The failures incident upon defective work—as all unbiased and properly trained thinkers are aware—are among the weightiest of the arguments that tell in favor of the employment of conductors.

In a very large majority of the cases in which accidents have occurred to buildings which have been furnished with lightning-conductors, the mischief has been actually traced by competent inquiry to some easily recognized fault or deficiency of construction. A very instructive illustration of the accuracy of this remark has quite recently presented itself in a form which is worthy of notice. Shortly after midnight, on the 26th of November, during a thunder-storm of some severity, a flash of lightning struck the lightning-conductor attached to the spire of Chichester Cathedral, and scattered a considerable portion of it into fragments. A letter from "A Fellow of the Royal Astronomical Society" forthwith appeared in the "English Mechanic and World of Science," drawing attention to the accident, and commenting upon it in the following words: "This seems to open a very serious question indeed, because, if so elaborate an affair as the Chichester conductor proved so much worse than useless when a thunder-storm came, what security have we that a similar disaster may not befall at, say, the Government magazines at Purfleet or elsewhere?" In reference to the accident which called forth this note of alarm, it may be at once, however, said that it belonged essentially to the class of occurrences which have been pointed at in the beginning of this paragraph.