Wellington Provincial Gazette – 1872 – No. 17

Page 182

✨ Survey Report

NEW ZEALAND
GOVERNMENT GAZETTE,
(PROVINCE OF WELLINGTON).

Published by Authority.

All Public Notifications which appear in this Gazette, with any Official Signature thereto annexed, are to be considered as Official Communications made to those persons to whom they relate, and are to be obeyed accordingly.

HENRY BUNNY,
Provincial Secretary.

VOL. XIX. THURSDAY, JULY 11, 1872. No. 17.

Report by Henry Jackson, Esq., Chief Surveyor, on completion of Trigonometrical Surveys over Crown Lands, &c.

Survey Office,
Wellington, 6th June, 1872.

Sir,— I beg to forward to your Honor herewith, a diagram map of the network of principal triangles which compose the Triangulation of the Province of Wellington, executed between the years 1866 and 1870.

The Trigonometrical Surveys, which were in existence prior to 1866, could scarcely be included under this nomenclature. They were unscientific in principle, and consequently erroneous in deduction. They merely included within their operations, in a disjointed manner, Port Nicholson Harbor, together with small portions of the Wairarapa and East Coast Districts. A strong prejudice existed at that time amongst the professional men in charge of the Survey Department, against this Trigonometrical mode of Surveying, which was condemned as impracticable in this Province, except at an enormous cost; whilst at the same time, it was regarded as a scientific theory from which no practical results could accrue. Thus it was not until so recently as 1866, that an organised system of Triangulation was commenced, when your Honor originated and intrusted to my charge the Trigonometrical Survey of the Province, on the completion of which, over Crown Lands, I have now the pleasure to report.

I will in the first place briefly sketch the method of procedure adopted in the operations, and then indicate the practical results which have accrued from their completion.

As a preventive to the accumulation of errors arising from a multiplicity of angular measurements, and at the same time to limit the character of the Triangulation in its prosecution, to the means at our disposal, it was intended at the commencement of the Survey to cover the Province with a network of triangles averaging 10 miles sides, to form what may be termed the major Triangulation, and that a secondary system of smaller triangles should succeed, taking for their basis these major sides. These principles were followed in the Wairarapa and over a large portion of the East Coast Districts; but owing to impediments presented by the natural features of the country in some localities, it was found necessary to modify this system either by reducing the size of the major triangles or by increasing them to such dimensions as would have defeated the main object of the Survey, viz.— the speedy determination of a sufficient number of triangulated points for the effective regulation of the chain surveys. The first mentioned course was adopted, and, confining the operations chiefly to the settled Districts and frequently checking the calculated deductions of the

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