On Lightning in New Zealand Mines.
London and New Castle-Upon-Tyne: Andrew Reid, Sons & Co., Printers and Publishers. 1892.
On Lightning in New Zealand Mines.
The writer begs to offer the following notes as an addition to the literature on this subject:—
I.—At the United Alpine Quartz Mine, situated near the Township of Lyell, and about 2,000 Feet above the sea-level, in the midst of the dense forest which covers this portion of the South Island of New Zealand, there was, on the 31st August, 1885, a very severe thunderstorm. The manager, Mr. Martin Conradsen, who was outside the adit-level at the time, states that he saw a flash of light strike the flat-sheets, and at the same moment the saw in the hand of a carpenter appeared to become a sheet of flame: he immediately dropped it. In the main drive, which was excessively wet, and laid along its whole length of 1,500 feet with 14-lb. iron rails, spiked in and not fish-plated, were two truckers and a horse; both the former received shocks, and the latter was knocked down on to his knees. At a distance of 1,700 feet from the entrance to the mine, and about 70 feet above the level, quite away from any metallic connections, were two men who stated that they had felt a shock as if they had been hit.
II.—The effects of the same storm were felt at the Koranui Coal Mine, near Westport. This colliery, which has since been abandoned, was 2,500 feet above the sea, surrounded by trees about 40 feet in height, with a dense undergrowth, and connected with the railway at the foot of the mountain by a series of five endless-rope inclines, laid with 14-lb. to 18-lb. rails, and having 3-inch circumference steel ropes. In addition to this was a double telephone wire, connecting with the five stations. No lightning conductors were employed. Mr. Jemison, the manager, informed the writer that on the date referred to he was in the mine at a distance of 560 feet from the level-mouth when he "heard a noise like a gunshot;" saw a "very bright light which he could have read by, which lasted several seconds and which appeared to pass by." At the same place were two men, both of whom felt a severe shock, which "seemed to rush up them, and a lifting sensation was felt." The rails in the mine were steel, and 14 lbs. per yard; the road was not fish-plated; there was a flat-sheet page 2 where the men were standing, and between them and the surface ran a signal wire and a steel rope, the latter passing at the in-bye end round an arrangement of three 2-feet pulley wheels. This portion of the mine was somewhat wet.
The influence of the discharge was felt by all the men below ground, approximately fifty in number, who thought that an explosion had occurred; the area occupied by them was about six acres.
During the storm a pony about 14 hands in height, standing outside the mine, was knocked down, and Mr. Jemison who stood near, felt the force of the shock and found that the hair on his forehead was singed. On the surface incline all the five brakesmen were considerably affected, and at the signal stations the copper wire was broken and fuzed and the telephones deranged. It was subsequently found impossible to maintain a system of electric signals. No explosive gas was ever found in the mine.
III.—On the same date, at the Banbury Coal Mine, belonging to the Westport Coal Company, Limited, which is about a mile from the Koranui Mine, and separated by a very deep valley, two men came out during the thunderstorm and complained that they had been fired at. There was at the time a serious labour disturbance, and the men were at work in defiance of the union. The impression produced upon them was one of extreme terror, and though it was a wet night, they ran home without stopping to put on their clothes. Their work-place was about 600 feet from the nearest outlet, of which many existed, as the coal-field is bounded by a vertical cliff, round which the outcrop extends, and to which adits have been frequently driven for purposes of ventilation. The road was laid with 14-lb. rails, not fish-plated, and no other conductor was available. On the same day, at a point 2,000 feet distant and 400 feet from another outlet, the metallic conductors being similar, a turn-rail was thrown out and the sleeper charred. Dirt was thrown up with violence from the floor against the roof, and a hanging lamp was broken.
Endless-chain haulage was in use at the time, but not up to the places mentioned, and it was not at all an uncommon thing during storms for the boys to receive shocks while handling the tubs. The mine is situated 2,000 feet above the sea, is worked level-free, and there is no gas.
The area of the storm was considerable, but the difficulty of collecting information, and the paucity of settlement in this portion of the colony rendered it not easy of exact definition.
At the Bealey telegraph and meteorological station, however, about 100 miles from the centre of the district occupied by the above-mentioned page 3 mines, and 2,140 feet above sea-level, the disturbance was carefully noted by Mr. Ryan, the telegraph operator and meteorological observer, whose observations may be best given in his own language.
"On Monday, the 31st August, 1885, at 10.45 a.m., I was away from the office, in another room, having left on account of the storm, when a blaze of fire seemed to come over the place, and sparks appeared to die away in a corner. No damage was done here, but on proceeding to the operating room, I found it on lire in several places. The current appeared to have entered the office, having broken the wires at the last post, and had fractured the leading-in wires, melting the gutta percha and copper and scattering red-hot pieces of the latter about. It then passed to earth. A noise like the firing of cannon was heard, about simultaneously with the ordinary peal of thunder. A telegraph pole 22 feet high, carrying two wires on insulators and fitted with a lightning conductor was, at a distance of 250 to 300 yards from the office, considerably shattered, the top being taken off for a length of 3 feet."
IV.—On the 21st May, 1885, the Banbury Coal Mine was previously the scene of electrical disturbances. The manager, Mr. Thos. Brown, who is a member of this Institute, wrote as follows:—"I enclose names of workmen who were struck with electric fluid. On the date mentioned the district was visited by the most severe thunderstorm I have witnessed in New Zealand. The lightning entered the mine frequently. The boys, who were hanging the tubs on and taking off the chain-slings, received shock after shock, until they were afraid to go near the rope. Mr. Cameron, the underground manager, then started to put on the slings, but after getting a few sharp shocks he considered it unsafe to continue work; the mine was therefore stopped for the remainder of the day."
The President moved that the discussion of this paper be adjourned. They had previously had communications on the same subject, and this would be an addition to the information at present in the Transactions. He moved a vote of thanks to Mr. Binns for his paper, which was agreed to.