MR A. D. DOBSON.

Timaru Herald, Volume CXXV, Issue 18191, 15 February 1929, Page 2

MR A. D. DOBSON.

SURVEYED FIRST RAILWAY LINE Few who worked on the construction of the Lyttelton tunnel have been spared to see the steam engine pass irom this line and modern electric traction take its place. One who has seen all this is Mr A. Dudley Dobson, of Christchurch, whose lather was tiie Provincial Engineer in the days when the tunnel was mooted, and who ably assisted the Superintended of the province in making this proposal a reality. Mr Dobson, as a young man, was engaged on tlio survey ot the first railway line in the Dominion, that between Christchurch and Ferrymead. Simultaneously with this work, the tunnel was being cut through the hills. For two or three years, Mr Dobson was stationed periodically at Heathcote. One of his particular jobs was to see that the tunnel was kept to its alignment To enable this to be done, a tower was erected on the top of the hills, another one in a direct line with it on the far side of Lyttelton tunnel, and tlio third on Ferry Road, also in a direct line. These towers were along the line of the tunnel.

The tower on the top of the hills, said Mr Dobson, in recalling his experiences, was about thirty feet high, and from this the other two towers could bo seen. In order to see that the 'tutnel kept to its line, observations were continually being kept at night, usually on Sunday night, for by that time the tunnel was clear of smoke. A candle in the tunnel, another in each of the lowers, and a transit instrument were used, and by this moans the direction was taken. A transit instrument being placed on the meridian of the tunnel, as well as the tower on the hill, it could be seen at once whether the flame of a candle piaccd i nthe centre line of the \ inside the tunnel, was in a vertical plane with the mark on the tower. But it was also desirable, in case of error, to have the means of not only correcting, but of calculating the amount of such error, and this was readily done. The permanent mark on the central tower consisted of a betten six inches wide, with a black stripe one inch wide jdown the centre. The eye-piece of the transit instrument being furnished with five vertical wires placed at equal distances apart, the value of the space between any’ two wires, at a distance equal to that of the mark on the tower, could be ascertained by f reference to the width of the batten, which thus gave a scale by r which the error in the position of a light placed in the tunnel under the tower could be rated with great correctness. It was by this means that the alignment was tested from time to time, and the proof of the correctness was established by results The two leading foremen on the tunnel job. added Mr Dobson, were Mr Martinaale, who supervised operations at the Lyttelton end, and who afterwards went into business at Lyttelton on his own account, and Mr Walker, who was in charge at the Heathcote end. He later took up land at Golden Bay, Nelson.

Mr Dobson also assisted Dr Yon Hnast in his geologic survey of the hills. The result of this survey enabled the contractors to know the type of country that they’ would meet, and the papers and plans of this work are now in the Canterbury Museum As the Port Hills are suppoesd to bo an extinct volcano, the report, from a geoolgical point of view, is very #interesting indeed. Before the tunnel was finished, Mr Dobson went to Nelson, where he established the waterworks, and, later, the gasworks, a portion of which is still in operation to-day,. His father saw the whole of the tunnel through from the start of the work until the steam trains ran through. For his work in Conner-ion with the tunnel. Mr Dobson’s father received the Telford Premium, a highly valued prize »-iven for exceptional services, by the British Institute of Civil Engineers. Mr A. Dudley Dobson, after being engaged in Nelson, did a considerable amount of exploring, among his discoveries being Arthur’s Pass, beneath which the Otira tunnel runs to-day.