Lightning Rod Conference. VariousЧитать онлайн книгу.
in the following list, and consequently cannot be given as separate answers to each question.
The replies were all numbered consecutively, so that the numbers omitted in the list refer to circulars returned by members who had no information to give on the subject.
REPLIES TO CIRCULAR.
2. St. Aubyn, J. P. Week St. Mary, North Cornwall.—The tower of this church stands on very elevated ground, and has lofty pinnacles, three of which have been struck at different times, on each occasion one of these pinnacles was shattered, and had to be taken down and rebuilt. Some of the stones are held by iron cramps, but no iron or other metal spindles. The roof of the tower, as well as that of the church, is slate, without spouts, and there are no lightning conductors to the building. There is open country all round the church, and no tree of any size within a mile of the tower.
The following detailed report was received direct from the Rev. G. H. Hopkins, the rector of the parish:—
An Account of the position of the Church of Week St. Mary, in the County of Cornwall, and the effect of Lightning upon the Pinnacle and Tower when struck for the fourth time this century on November 8th, 1878.
Situation of the building.—The situation of the church is at the northern angle of an extensive triangular plateau, which towards the south is much broken by small valleys and low hills, while the high land is for the most part moor, broken in places by cultivated ground and small plantations. Within a quarter of a mile from the church, on three sides, the ground commences to fall very rapidly to a depth of 200 or 250 feet; it is three miles from, and nearly 500 feet above, the sea; to the N.W. lies Widemouth Bay, one of the very few breaks in the cliff along the coast of North Cornwall; the entire extent of this break is quite a mile-and-a-half; between the Bay and the extremity of the plateau, at which the church is built, the surface is broken by low hills, only one of which exceeds 250 feet above the sea level, and this exception is separated by one valley from the church hill; half a mile south of the church is the highest ground in the parish, but neither this nor any hill for several miles exceeds in height the pinnacles of the tower. The elevation of the building above the surrounding country can be better understood from a local rumour that 28 churches are visible from the battlements of the tower, and the average size of a parish attached to each church is 6000 acres. The highest point of the pinnacle is 90 feet above the ground.
No mines or spring of water beneath it.—There is no evidence of the existence of any metalliferous lode in the parish, and certainly no such attractor of electricity lies beneath the church, nor is there any spring of water near the foundations; but as the surface soil is clay, the rain water has no means of flowing away, except over the surface, and a few hours of moist weather make the soil like a wet sponge.
Circumstances.—The tower was struck at 6.45 a.m. on November 8th, 1878, the weather having previously been gusty, with sudden storms of hail and rain as each heavy cloud came up from the sea: many times during the night the downfall of hail was very violent, and it was during one of these storms that the single electrical discharge took place; the hailstones were considerable, both in number and size, when the flash occurred, and they certainly commenced falling before the shock took place.
Brightness of the flash.—The brightness of the lightning was intense, and I have been at some trouble to inquire into the effect which it had upon those who saw it. I was awake, and the lightning illuminated the room through double chintz curtains and dark-green blinds, the windows looking away from the church, and being more than a quarter of a mile from it; during the storm a farmer took refuge in a closed cattle shed, 200 yards from the church, and he spoke afterwards of his impression that he was surrounded by fire; two farmers going to Camelford fair, were at the time waiting on the road, a mile-and-a-half from the church, and their impression was that they were enveloped in flame, and the flame came between them; these experiences were given to me at different times, and were independent evidences of individual opinion. At Holsworthy, eight miles away, in a direct line, two ladies were attending their sick mother, and the vividness of the lightning obscured the brightness of the light of two candles and a paraffin lamp.
The loudness of the thunder.—The loudness of the clap of thunder was very great; of course it shook my house; and a neighbouring rector, who lives three miles away, in an adjoining parish, felt the effect of the clap to an extent which was very unusual; at Camelford, lying W.S.W., and distant about twelve miles, with a considerable range of hills between, the thunder was not heard; but two miles nearer, and in the same line, it was just heard: this latter station being on the summit of the range; at Holsworthy, lying E.N.E., it was heard as an awful peal; at Kilkhampton, which lies directly N., and separated by a broad broken valley, the thunder was blamed with causing colts to break through a fence from terror, and the distance is ten miles. I am unable to give any further account either of the distance the thunder was heard, or of the intensity of the light of the flash. As the wind was blowing from the west, with a slight bearing towards north, the effect of the wind upon the sound is evident.
Effect upon the pinnacle.—The S.W. pinnacle (A) was struck, and apparently the effect of the lightning was not felt upon the two uppermost stones, namely a small cross and a truncated cone, which supports it at the summit, both of granite. It may be remarked that the entire facing of the tower is granite, the interior masonry being made up of small stones of different kinds, which exceeds 3 feet in thickness, while the blocks of granite which face the tower vary from 10 to 12 inches in thickness, and in some cases are of immense size and weight. As soon as the current could reach that part of the pinnacle which is made up of courses of separate stones, the mischief commenced, and the effect was to force the stones out all round the axis of the pinnacle, so that in the same course many of the stones were separated by intervals of from 1 to 5 inches; one great block, measuring 2 feet in length, was thrown right out, but fortunately fell outside the tower walls, and left a gap in the pinnacle opening towards that quarter from which the storm came. The entire pinnacle was shattered, and all the courses of stones which make it up dislocated, as well as the two courses of stones which lie beneath it. The fierce rain storms had long ago washed away all the mortar from between the stones which compose the outside of the tower, and probably every shower wets the interior of the masonry; and this was especially the case at one part where there is a considerable leak of drainage from the roof of the tower.
Effect upon the tower.—The course of action of the current was from the pinnacle to this leakage, where a stream of water was running down the wall and between the granite facing and interior masonry; the downward course of the water was arrested by the belfry light, and then has to fall to the masonry below the window; just above the window a large block of granite C (outside measurement 2 feet by 14 inches), was thrown out in such a way that it hangs like a halfopen door, the projecting edge being that which lies just below the leakage, and standing out about 10 inches from the wall; across the belfry window runs an horizontal iron bar, and at the bottom of the window lies an old iron bar; the stonework beneath this bar was much knocked about. From that spot the effect of the lightning disappears, until it reached an immense carved granite block D, which lies on the south side of the tower, and very near its south-east corner; and a few feet below this the leaden gutter E (through which part of the roof drainage is poured to the ground), runs some feet down the wall towards the earth, but does not reach the earth by 12 feet. The immense carved granite block is broken into two almost equal parts by a line parallel to its vertical edges, and the two parts are separated by quite half an inch; the fracture of the stone is not quite straight nor clean, and the parts of the stone do not project beyond the surface of the tower. I have been unable to trace the course farther; it may have passed along 70 feet of leaden gutter, between the nave and south aisle (F) to the east end of the church, or gone to ground at the base of the tower. Three or four days later, during a very high wind, a second stone fell from the pinnacle; this same stone had been partially thrust out on a previous occasion in 1865.