Experiments concerning the different efficacy of pointed and blunted rods, in securing buildings against the stroke of lightning / [William Henley].

  • Henley, William.
Date:
1774
Catalogue details

Licence: Public Domain Mark

Credit: Experiments concerning the different efficacy of pointed and blunted rods, in securing buildings against the stroke of lightning / [William Henley]. Source: Wellcome Collection.

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    I T *7 ] offharp pointed conductors, fo immediately relate ing to the queftion under confideration, that no apology will be neceftary for introducing it in this place. Dr. winthrop, having given a very cu¬ rious and exaCt account of a violent flafh of lightning, which fell upon and greatly damaged HOLLXS-HALL, ill NEW CAMBRIDGE, obferves, thatHARVARD-HALL, being furniflied with pointed wires, which wires were at the diftance of one hundred and fixty feet from the chimney of Holiis- hall, on which the lightning fell, efcaped unhurt, though the wires were feen by many to tranfmit a large quantity of it, which left vifible marks upon the bricks, where the wire hooked together. This gentleman alfo obferves, that a tree, ftanding at the diftance of fifty-two feet from a pointed wire, ereCted upon the fteeple of a meeting-houfe, as a conductor for the lightning, had been ftruck and Ihivered; but that the meeting-houfe remained uninjured; and this, he fays, is the leaft diftance from fuch a conductor, fo far as he knew, at which any thing had been ftruck by lightning. It appears, therefore, I think, very clearly, from thefe inftances, that ftiarp pointed wires, inftead of inviting, and drawing down ftrokes of light¬ ning, ferve rather to prevent them, and that they extend their protecting influence to feme diftance around them, and ought therefore ever to be uled, as the termination of the rods ereCted upon houfes, fteeples, magazines, mafts of fhips, &c. in fhort, on all occaflons, where conductors for the light¬ ning may be thought neceflary. C I can-