THE New Zealand Herald AND DAILY SOUTHERN CROSS. MONDAY, JULY 19, 1926. ARAPUNI'S PROGRESS.

New Zealand Herald, Volume LXIII, Issue 19383, 19 July 1926, Page 8

THE New Zealand Herald AND DAILY SOUTHERN CROSS. MONDAY, JULY 19, 1926. ARAPUNI'S PROGRESS.

A MILESTONE in the progress of the great Arapuni hydro-electricity scheme was passed on Saturday. Diversion of the stream preliminary to its damming became a fact accomplished in part. The first and most critical phase of the operation has been performed with complete success. Now, unwearied, indeed inspired to new effort, the great com- | lunation of human mind and muscle. [ allied with the refinements of | mechanical equipment, will be con- ; centrated afresh on the greater tasks still waiting. The hurrying waters will be further turned, bound and disciplined, while the great dam rears its bulk across the gorge, the waters back up until the mighty lake planned years ago becomes a reality. Then the stream will be turned into the channel through which it flowed in an earlier geological age. As the gigantic scheme proceeds to its fulfilment, power-house and equipment will be fitted into place against the great day when the turbines begin to revolve. The crowning will come when Auckland homes glow with the light and Auckland wheels spin to the thrust of the power that was once the tumultuous energy of the Waikato racing through the Arapuni Gorge to the sea. The scheme is as great in conception, planning and execution as it is expected to be in consequences. Its magnitude has caused doubts and reservations in some minds. Their answer should lie in the smoothness with which work has proceeded. There should be a very special reassurance in Saturday's success, for the work done so neatly and so swiftly was acknowledged by the experts to be critical in character, a real test of engineering technique. It is easy to quote figures illustrating the magnitude of the undertaking at Arapuni, for the details have been worked out with painstaking exactitude. It is not so easy to make the illustration real to those without experience and training enabling them to visualise what the statistics imply. For instance, a representative of the contracting firm, at the time when the contract was signed and sealed, said the excavation to be done amounted to 250,000 cubic yards, mostly of rock: the materials to be handled included 120,000 cubic yards of concrete, 172,000 tons of crushed stone, 30,000 tons of cement and 57,000 cubic yards of sand. It all sounds imposing, as big figures always do; but none of it is so impressive as was five minutes spent standing on the lip of the gorge, before the work began, gazing down at the waters as they raced through the channel in which they were pent. To those who did not realise the capabilities of modern engineering, it seemed futile to think of stemming the rush, of building on foundations lying far below that torrent, of turning the stream and taming it so that it ran, just as swiftly, but under discipline, through the turbines into the tailrace, and so on its way with its work done. It brings facts nearer to ordinary comprehension when it is stated the average flow of the river at Arapuni is 7000 cubic feet per second, the lowest on record 4800 per second, and the highest 32,000 per second. The natural velocity at the dam site is 10 feet per second. When the dam is built there will be a lake 18 miles in length formed behind it. Its area will be over five square miles, or nearly 3500 acres, and its volume 5,117,000,000 cubic feet of water. The amount of power inherent in this great mass is revealed by the official calculation that a fall of one foot in its level would develop 200,000 horse-power for 6ihours. The resources of the river are shown by tie statement that, utilising only one-half of its average or normal flow, this great lake would be filled in 17 days.

The figures concerning Arapuni are significant or meaningless according to the mental grasp of those who consider them. To the trained mind they bring a vision of the patient preliminary investigation, of the months of toil, each piece of work laid out in advance, attacked according to plan, and rigidly tested at every stage up to completion, and finally of the accomplished feat, the power scheme in operation, the current generating and flowing over the country to its several purposes. To another expert there is the question of capital invested, of interest and sinking fund, balanced against the demand for current, together with the price, down to the monthly bill of the householder. The layman cannot be expected to come to full realisation at once. He knows there is something of unusual magnitude in process of execution, he has perforce to accept assurances that nature can be tamed with technical success, and that the price which he, as a taxpayer, must guarantee is not too great for successful operation. But he should remember that the figures are only the raw material of engineer and accountant, that the work of harnessing the river is only a means to an end. The real purpose behind the whole conception is to bring light and warmth to his j home, and power +n turn the wheels ! of industry for the greater prosperity of himself and his fellow citizens. The real meaning of Arapuni lies, not in the engineering feat it involves, and not in the great financial operation it demanded at the outset. Its fulfilment will mean that a mights natural asset, for centuries running to waste unchecked, will have been taken up, developed, and applied to the purposes of national well-being and social progress. That is the aim far beyond the organisation, planning and execution of the great work which passed an important stage when the explosives were fired on Saturday, so that the water might pass into the diversion tunnel.