NEW ZEALAND SURVEYS.

Globe, Volume IV, Issue 301, 31 May 1875, Page 4

NEW ZEALAND SURVEYS.

The following report of the remarks made by Mr M'Kerrow, chief surveyor of Otago, at a meeting of the Otago Institute, is taken from a Dunedin contemporary : “Mr M'Kerrow said that Mr Connell’s paper was a very valuable contribution on colonial surveying, and his definition of the object of such a survey, viz ;—To give possession of a portion of the earth’s surface, not necessarily having any permanent marks, or other evidence within itself of its boundaries, is at once comprehensive, and marks the difference between the survey of an old and “of a new country. In an old country the prime object of the survey is to produce an accurate map of the country, as already occupied; in a new country the map is also important, although very secondary to the accurate definition of boundary. This accuracy is necessary, not that the settler may have exactly to a square yard the area he purchases, but that in case of obliteration or challenge of boundary he may have the means, through a competent surveyor, of reproducing his boundaries. As the country gets improved, and the post and rail are superseded by live fences and other permanent marks, disputes as to boundaries will vanish. It is all important then, that the foundation sectional surveys be accurate. And as these surveys in a new country are described in grants and transfers solely in terms of angles and lines, the work naturally rests on a trigonometrical bisis. Every experienced surveyor knows that although he may with every confidence lay off isolated sections accurately as to

dimensions without any reference to the trigonometrical survey, yet he cannot extend his operations with any confidence unless he has trig points to begin and close the work. Hence triangulation must precede sectional survey, for, as Mr Connell well observes: The object of triangulation is to check and prevent error, not simply to detect it after it is too late for rectification,

It is heie we confront the Colonial survey difficulty. To carry out our ideal the surveyor should hsve had the country some years to himself before the settler appeared, and should have had time to measure his triangles and all the trig stations ready before the advent of settlement. But this is simply Utopian. The settler is usually before the surveyor, and, indeed, there would be no need for surveyors at all but for the development of the country by the hardy settler. The surveyor therefore cannot have the country given up to him, he must work along with the settler, He can, however, take a comprehensive view of his work, and begin on a system that can be worked out intelligently till every acre of the country is surveyed and occupied. Such a system has been referred to by Mr Connell as that of meridional circuits. Under this system standard points are established over wide areas in a very short time. Surveys are then begun on standard data wherever settlement demands, and under this system the surveyor virtually succeeds in after all getting the first of the country, for he takes care to have the minor triangulation and topographical survey in advance of settlement. The work is done once and for all. And it may be begun at a dozen different points with the satisfactory feeling that all the work will close and form one consistent whole. This system is peculiarly applicable to new countries, for the amount of work can either be extended or curtailed, just as there are means to prosecute it, without detriment or loss to what has already been done. “Mr Connell, among other recommendations as to greater accuracy, advises that the limit of error of eight links to the mile should be diminished to four links. If the snrvej ors were all Connells this could very safely be done. But it is better to have the larger limit and always come within it, than pretend to an accuracy that would require constrained efforts in some cases to comply. Since no point or line is ever more than a mile, or, at the most, more than two miles, from a trig, station, the maximum error is not so much after all.”