07 August 2015

Peter Seton Hay (1852–1907)

Peter Seton Hay was born in Glasgow and came with his parents to New Zealand in 1860. He was educated in Dunedin, becoming the first Bachelor of Arts (BA) of Otago University in 1877. He followed this with a Master of Arts (MA) with first-class honours in mathematics the next year. He had joined the Public Works Department as an engineering cadet on 13 June 1875, being stationed for a short time in Wellington then transferred back to Dunedin on 6 May, 1875, no doubt to enable him to continue his studies. As a cadet he was engaged, among other duties, on the survey and construction of the Dunedin to Moeraki and the Dunedin to Clinton Railways.

At the end of his cadetship in 1879 he was promoted to Assistant Engineer at Dunedin. Though nominally at Dunedin, his work included the survey of the Otago Central Railway from Rough Ridge to Hawea.

He was at Cromwell in 1881. It is recorded that during this work he left his book of logarithms and trigonometrical tables in camp. Rather than waste a day or walk back for the book he sat down behind a rock and proceeded to work out the necessary tangents and calculations from first principles. He also surveyed the railway from Balclutha to Catlins River.

On 1 May 1884, his brilliant mathematical talents having marked him out as a head office man, he was transferred to Wellington, being two years later graded as Resident Engineer. His duties, however, were chiefly design work and assisting the Engineer in Chief on difficult problems.

In 1894 with ER Ussher, he reported on the enormous accretion of sand taking place in Caroline Bay. He recorded that the three fathoms line had moved 700 feet seaward since the construction of the harbour works.

In 1899 he was associated with TH Rawson as a commission to report on the proposal of JP Maxwell to construct a new East mole at Timaru.

In 1896 he had been promoted to Superintending Engineer. On 29 January 1906, he became Acting Engineer in Chief and was confirmed in that position on 1 April 1906, on the retirement of WH Hales. He also became Marine Engineer.

During this period he designed: the Makohine, Mangaweka, Hapuawhenua, Toanui, Manganui-o-te-Ao and Makatote viaducts, and many other bridges on the North Island Main Trunk Railway; the Awatere two-decker road and railway bridge; the Farewell Spit Steel Lighthouse, and many other big works. He advised on the restoration of the Rakaia Gorge Bridge wrecked by wind, and the strengthening of the Christchurch Exhibition towers. He also reported on Motueka Harbour. However, he will always be remembered for his exhaustive 1903 report on the hydro-electric potentialities of New Zealand.

Probably his greatest work was to identify the best way for the railway to cross the Southern Alps. Many schemes had been tried, and at the stage when Hay came into the question the Midland Railway, after trying and rejecting a 1 in 50 series of grades over the top, and other ideas, had finally pegged out a location for grades of 1 in 15 on each side of the range with no summit tunnel.

He came to the conclusion that the best grade that the country would allow on each side, following the valley bottoms without undue earthworks, should be adopted, and then the open-air work should be connected by a tunnel on the grade which was then required, approximately 1 in 37. The tunnel was to be about six and a quarter miles long.

The Government of the day, on the principle that distant fields look green, decided to bring from North America a railway engineer of outstanding reputation and ability, Virgil Gay Bogue, and to obtain from him a report on the whole problem. He considered that a certain amount of grading up and development on the western side on a grade of 1 in 30 should be done and that the tunnel, on a grade of 1 in 33, could then be reduced to about three and a half miles. Hay prepared a counter report and proved that if 1 in 30 grade, which Bogue had recommended, was not too steep, then an almost straight line could be built (without the development in rough country, with attendant slip and avalanche dangers), which would be shorter than Bogue's line, no steeper, and would cost less, even though the tunnel would be over five and a quarter miles long. Hay's grade throughout was 1 in 33. When this new solution was referred to Bogue, he admitted that Hay's solution was the one which should be adopted, and it was.

This, the writer considers, was Hay's greatest triumph, but unfortunately he did not live to see its consummation. He died on 19 March 1907, as the result of illness brought on by exposure when inspecting the works on the North Island Main Trunk Railway.

More information


Frederick Furkert, Early New Zealand Engineers (Wellington: Reed, 1953), pp.183–85.

Further reading

Peter Lowe. ‘Hay, Peter Seton’ from the Dictionary of New Zealand Biography in Te Ara - the Encyclopedia of New Zealand, updated 28 August 2014.