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Original Message
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[Comment: Anyone know why this phenomena seems confined to Australia and New Zealand? NexusEditor]
The earth of New Zealand, a bad Conductor of Electricity, as compared with that of other countries.
By F. E. Wright. Read before the Philosophical Institute of Canterbury, New Zealand, September 1, 1869.
MY attention was first attracted to this subject under the following circumstances:—
In March, 1867, I had occasion to visit Hawkswood, in the Nelson Province, and I returned to Christchurch via the Cheviot Hills, following the line of telegraph all the way back.
Between Hawkswood and Glenmark I saw that a large number of the telegraph poles were lying on the ground; they were birch saplings, and most of those still standing appeared to be so badly rotted at the point of their emergence from the soil, that I have but little doubt many more fell during a south-west gale which detained me two days at Mr. Moore's station. I need hardly state that the poles for the whole of the distance, here referred to, have been replaced by others of a more substantial character.
Under these circumstances, on arriving at Christchurch, I felt it almost useless to ask at the Telegraph Office, if the line was open to Wellington, and was greatly surprised to find that messages could be forwarded. This was at variance with my previous knowledge of the subject, and I thought it so curious and exceptional, that I have since lost no opportunity of enquiring into the matter, the result of which has been a settled conviction on my mind, that an altogether anomalous state of the soil, so far as its conductibility of electricity is concerned, obtains in these Islands.
Mr. de Sauty, the late electrician of the telegraph department, who is quoted as an authority in several recent works on telegraphy, and who had been engaged on telegraph lines in various parts of the world, assured me that he was unaware of any other country or place exhibiting similar characteristics.
Mr. Bird, the present Provincial Inspector of Telegraphs, informed me, a year or two since, that were the conditions of the earth as a conductor of electricity the same here as in Europe or America, it would have been quite hopeless, for months together, to have endeavoured to send a telegraphic message in any direction from Christchurch, there being faults in all the lines, which would have proved sufficient to destroy the connection in any other place but New Zealand.
Mr. Meddings, attached to the Telegraph Office in this city, who takes the greatest personal interest in his vocation, and works at it with a zeal which may be termed enthusiastic, has made many interesting experiments on the subject. He tells me that he finds the greatest difficulty in getting a good dead earth in Christchurch, or in fact in any part of New Zealand to which he has been called by his employment.
This anomalous state of the earth in this country was at first to some extent accounted for, in my mind, by the dryness of the soil, thinking that the absence of moisture on the plains might render the ground a bad conductor; but I have since learned from Mr. Mason, the gentleman at present in charge of the Telegraph Office here, that in some of the very driest districts of Australia, it is only necessary to force a small iron bar a few inches into the ground, effectually to disperse any electricity which might be conducted to it; whereas in Christchurch, where, a foot or so from the surface, the ground is at all times moist, an earth plate of the size ordinarily used in England disperses the electricity in a very imperfect manner.
Mr. Meddings, in one instance, connected the wires with the pipes of an artesian well from which the water was flowing, and it proved a very imperfect dead earth for the electricity conducted to it. He also experimented on a telegraph line forty-one miles in length, in the Province of Hawke's Bay, with the following results. He generated the electricity at a point about a mile from one of the extremities of the line, which was connected with the earth by wires and earth plates, at this point, as also at the nearest extremity.
This under all ordinary states of the earth in other parts of the world, would, I am led to believe, at once have disposed of any current of electricity sent along it; in place of which, however, the electricity was resisted by the earth at each of the places where it was connected with it, and was forced to the more distant extremity. At the Cheviot Hills Station, which is provided with an ordinary earth plate, a considerable portion of the electricity finds its way to Christchurch, when it should be absorbed in the earth at the station.
I must ask your indulgence for the crude and superficial character of this short paper, but I trust that the subject which I have thus had the temerity to bring under your notice, may lead to its investigation by others more able to expend time, and bring knowledge and requisite appliances to its elucidation.
(Source: Transactions and Proceedings of the Royal Society of New Zealand 1868-1961; Volume 2, 1869; page 226. [link to rsnz.natlib.govt.nz]
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