The tower, which was erected in 1424, and is one of the landmarks of Oxford, had not up to the time of the accident been provided with lightning conductors, but they have since been affixed to the building.
[Fig. 44] shows the steeple of St. Bride’s Church, Fleet Street, London, which was severely damaged by lightning on June 18, 1764. The spire of this steeple is built in four storeys, surmounted by an obelisk. These four storeys are braced together by means of horizontal iron bars; another iron bar, about twenty feet long and two inches square, passes through the upper part of the obelisk and supports the weathercock and other ornamental work on the top; there is also a great deal of iron-work used generally in the construction of this part of the building, thus forming a complete series of discontinuous metallic masses. When the lightning struck the building it was received by the long iron bar which supported the vane; at the lower end of the bar the electric discharge, meeting with no metallic conductor, burst with great violence, shattering the stone on which the bar rested; the lightning then pursued its course to earth, leaping from one piece of metal to another and breaking the stone-work in its way. The last trace of it was found at the west window of the belfry, from whence it seems to have found a road to the earth. The damage sustained by the structure was so great that eighty-five feet of the spire had to be entirely rebuilt.
The edifice was afterwards attentively examined (as explained in a previous chapter) by Dr. Watson, a well-known electrician in those days, who reported to the Royal Society that the accident ‘completely indicated the great danger of insulated masses of metal to buildings from lightning; and, on the contrary, evinced the utility and importance of masses of metal continued and properly conducted, in defending them from its direful effects. The iron and lead employed in this steeple, in order to strengthen and preserve it, did almost occasion its destruction; though, after it was struck by the lightning, had it not been for these materials keeping the remaining parts together, a great part of the steeple must have fallen.
Fig. 45.
[Fig. 45] shows the condition of St. Michael’s Church, at Black Rock, near Cork, after being struck by lightning on January 29, 1836. The damage done was entirely on the windward side of the steeple, caused, as is suggested in Mr. Tomlinson’s work, by this side receiving the greatest quantity of rain, and so being rendered the ‘line of least resistance,’ but not a sufficiently good conductor to carry off the discharge to earth.
On Trinity Sunday, June 8th, 1879, a violent thunder-storm broke over the town of Wrexham about half-past three in the afternoon, during which the spire of St. Mark’s Church was struck by lightning. A Sunday-school class was being held in the room at the base of the spire, and the teacher and five of his scholars were burnt, three of them severely, and one had his leg broken. Some of the stone-work of the spire was also displaced and thrown down. The spire was fitted with a copper conductor, but it was of too small a calibre, and it is very doubtful whether the earth connection was all it should have been.
Many other cases might be enlarged upon, but enough have been given to prove the imperative need for a more general use of lightning conductors on all public and private buildings. Another equally important necessity is that lightning conductors should be erected on sound principles, and also be periodically examined and tested by some competent person.
PUBLIC BUILDINGS STRUCK BY LIGHTNING.