SCIENTIST AT WORK

Waikato Independent, Volume XL, Issue 3664, 6 February 1940, Page 5

SCIENTIST AT WORK

Nliiw POWER STATION INVESTIGATIONS AT KARAPIRO AMAZING EQUIPMENT USED (By C.W.V.) How the amazing developments of science are being applied in testing the site for the future power station, and dam on the Waikato River at Karapiro, is shown by the work at present being carried out by Mr Norbert Modriniak, and his two assistants, on behalf of the Public Works Department. For some weeks past farmers on both sides of the river have heard and felt explosions from time to time, and perhaps have wondered what was their import. Few realised that they were anything different from the explosions heard at Grinters' Quarry in recent years. Actually, this intermittent blasting was part of the geophysicist's method of finding out what lies below the surface of the ground, or under the river bed, without having to drill holes or sink shafts in order to do so. These latter methods have been used at Karapiro, but, of necessity, they can only reveal what lies in the immediate vicinity of each bore. It is vitally necessary that the new dam and power-house should be built on solid foundations. It is the geo-physicist's job to prove beyond all doubt the depth and solidity of the rock on the site of the new station. He works on a method somewhat differing from, but not unlike, that now used at sea for taking soundings. This is based on the time taken by a s sound wave to travel from the bottom of a ship to the sea-floor and back again to the recording instrument. A Moveable Base Mr Mqdr-iniak has a moveable base of operations. This consists of a huge van weighing, with its contents, several tons, and looking like something between an armoured car and a "biack-maria" (except that it is painted grey). It is packed with an amazing array of electrical equipment which puzzles the layman/ but/ like most seemingly complicated pieces of mechanism, is simple to the expert. Shut inside this van, behind solid steel doors which almost hermetically seal him inside, in a space that just leaves him room to move about, Mr Modriniak can read the secrets of the earth below him, almost as clearly as an airman can see what is happening on its surface as he flies over it. Gelignite Charges Used At the back, of the lorry, just inside the, outer doors, are two reels of electric cable which link it with a series of seismographical recorders let into the ground along the line which it is desired to investigate. The placing of these instruments (which appear to be only smooth cylinders of stainless steel, rouridedat one end), and of firing the charge of gelignite, are the responsibility of his assistants. When everything is ready; Mr Modriniak gives the order to fire, much as a gunnery officer, similarly surrounded by instruments and winking coloured lights in the control top of a battleship, might do. He is in verbal communication with the men outside by wireless telephons, and by morse signals, through an amplifier mounted on top of the cab. r Like Wireless Waves When, the charge is fired, the casual observer sees only earth and rocks* and dust.flying, and is deafened temporarily by the shock. The explosion has done more however, than to tear a crater three or four feet wide in the ground, and nearly shatter the onlooker's eardrums. The impulses from the shot travel in all directions, just like wireless waves. They travel along the surface, and strike down into the earth as well. ' : Unlike wireless waves, however, when these impulses come into contact with a strata of hard rock, they flash along it with the speed of thought—but not too fast for the instruments under Mr Modriniak's control to register the fact —and then strike upwards to the surface again, some distance away. The recorders already mentioned automatically register the time these impulses take to perform this split-second journey through the earth. The actual passage of the vibrations is recorded" on a roll of sensitised paper which, when developed—a matter of a couple of minutes only—produces a series of

wavy lines of eccentric pattern, which look like a seismograph record of an earthquake. This, in effect, is exactly what it is, only on a much smaller scale. From these are made mathematical calculations which tell the expert what he wants to know. By repeating this process over a given area of country, and on different bearings, a very definite idea of its structure, and the extent and solidity of the underlying rock strata can be obtained. It all sounds very simple, but there is much involved in the working of the various instruments which the lay mind can but vaguely grasp. Developed Since Last War This method of earth exploration has been developed on the Continent since the Great War, and has been used extensively there, and also in America, where it has proved of great value in the search for new oil-fields. In the early nine-teen-twenties a German scientist applied the same method to measuring the frequency of waves in the Bay of Biscay. Like most pioneers, he was scoffed at, but his discovery was improved upon by other German and Hungarian scientists, until it has now reached a stage of uncanny precision. Mr Modriniak, who is a naturalised New Zealander of Austrian birth, has been in the Dominion for thirteen years making similar tests in. connection with the discovery of possible oil-fields. It is interesting to note that the first geological survey of New Zealand was carried out by another Austrian—Baron F. C. von iHochstetter, who was specially engaged in 1859 by the Government for that purpose. It was he who compared the beauty of the Waikato River, on seeing it for the first time, with the Danube or the' Rhine.