SURVEY REPORT.

Survey Office,
Dunedin, 20th July 1859.

SIR—I have the honour to report, for the information of the Waste Land Board, the results of last year’s Survey operations, and would solicit the attention of the Board to them and other matters affecting the Survey.

On reference to the accompanying Return, it will appear that 156 square miles have been triangulated, 122½ miles of road have been lined out and surveyed, 70,870 acres have been marked on the ground and surveyed, and 1594 town allotments have been laid out. The total cost of the above service, as will be noted, amounts to £2965 6s. 1d.

Regarding Mr. Garvie’s services, I beg leave to state that they were principally directed to surveying and marking main lines of road through the Otago Hundreds, a pressing necessity having arisen for the same owing to the original contract surveys executed at the foundation of the colony not having embraced these important operations. Nine miles of heavy bush have been cut through, and ten miles of side cutting on open land were marked on the ground by a rut with the spade; further, 16 miles of bush lines have been cut, but whose survey has not yet been overtaken. Included in these services are the main lines over Hillside, altitude 90 feet, and Look-out Point, altitude 370 feet, being part of the main southern road; and the main lines over Mihiwaka, altitude 1100 feet, and Signal Hill ranges, altitude 1000 feet, being part of the main northern roads. These lines have been marked to a gradient of 1 in 16, which will admit of carriage traffic on the lines being formed and metalled. These surveys have involved much labour and exposure, and I have no doubt will prove of great public benefit.

Mr. Gillies’ services have principally been directed to the triangulation and section survey of New River Hundred; also to the survey of part of the 2000-acre blocks. It becomes me to particularly notice these surveys, which have all been executed with a 4-inch Everest Theodolite. In the triangulation, each bearing was the mean of nine readings, and the accuracy of the work will be seen by the following:

NEW RIVER TRIANGLES.
The average error in each angle is 4 seconds
" greatest error on an angle is 11 "
" least error on an angle is 0 "

The base lines were measured on level ground by a standard chain, carefully adjusted, each base line being the mean of three measurements. The greatest difference in any of these measurements amounted to no more than 0.88 of a link per mile, and the least no more than 0.14 of a link per mile, the average being 0.51 of a link per mile. Thus it will appear that Mr. Gillies’ minor triangulation on the whole involves only an error of 15-100ths of a foot per mile in bearing, and 33-100ths of a foot in distance, an accuracy tenfold greater than the chain measurements which follow, and which the triangulation is intended to check.

The chain measurements conducted for the survey and marking off of the sections have been found to close with the calculated measurements of the triangulation by which the former are checked, by 3 to 6 links in the mile, as the ground was favourable or unfavourable. This amount of error proves careful measurement, and is as close as can be attainable on such ground as we have in this part of New Zealand.

Mr. Briscoe’s party was employed in laying out two villages (Moeraki and Oamaru), and in surveying and marking on the ground the main southern road between the Taieri and Popotunoa. 57½ miles are reported as completed, but only 28 miles have been given in available for record.

Regarding the services of Mr. Hately, I beg leave to report, that he joined the staff in the latter end of October as a sub-assistant only, not having had experience as a surveyor previously. His first operations were under the eye of Mr. Gillies. This officer, besides having done a fair amount of survey, has executed the same satisfactorily, as shown by his closing with the points of Mr. Gillies’ triangulation. His greatest error is 9 links to a mile, and least 1½ links, the average being 3 to 4 links.

The cost of the public surveys of the year prior to this was found to be 7½d. per acre, including the cost of triangulation. This year the cost may be arrived at by analyzing Messrs. Gillies and Hately’s operations, the times being given to effect the same.