CU-1 A.

REPORT.

The work executed by the staff in field and office during the year ended 31st March, 1940, is set out in the tables appended hereto. Generally the amount of field-work shows a slight falling off as compared with last year's .return. This is probably accounted for by the adverse weather conditions during the season, and the costs have consequently risen to the same extent. Office-work as shown in Table 4 is, on the other hand, a little more than last year. Field. Geodetic Triangulation.—The area completed this year comprised the whole of the Canterbury district and the northern portion of Otago district. In the geodetic network (including base nets) 37 stations were occupied and the resulting 102 closed triangles show an average triangular error of one second. Besides these, 23 stations of lower order-work were occupied, the resulting 82 triangles having an average close of 14 seconds per triangle. In attempting to make an economical use of the lights, observations for latitude and for azimuth were not taken at the same time, and several stations will need to be re-occupied for latitude observations. Mr. W. G. Nelson, Surveyor in charge of the geodetic party, reports : — " Bilby steel towers were used on the Canterbury Plains in order to obtain lines of suitable geodetic length. Considerable delay was experienced in obtaining delivery of the towers, and second-order work referred to above and which was commenced during the winter, when the weather was too severe to permit of geodetic observations on higher country, was continued. Trig, signals were also built on certain geodetic stations whilst awaiting delivery of the towers. " Observations conforming to geodetic specifications were obtained on the towers, but the observers had to wait until the weather was practically calm in order to do this. The delays thus occasioned were such that it was considered advisable in February to transfer the operations of the party to the higher country in Otago before the season became too late for the safe occupation of stations situated at a considerable altitude. Good progress was made on Otago stations, and the programme as approved by you will be completed before the winter renders further night observing impracticable. " The Waitaki base-line was prepared for measurement during the winter. " The delay referred to above in delivery of the towers involved a corresponding delay in commencement of observations till the spring, when the seasonal north-west gales in Canterbury hampered observations ; also considerable quantities of timber were required to be purchased for trig, signals. In this connection twenty-one wooden signals and one steel signal (on Rangiora water-tower) were erected and one signal repaired. " Wooden towers 30 ft. in height were erected on six stations. Timber sufficient for three towers was purchased, and the towers after first erections were dismantled and re-erected as required. " Wooden towers 15 ft. in height were erected on four stations. One tower was purchased and, after first erection, dismantled and re-erected as required on various stations. " The two Bilby steel towers were erected on four stations —viz., to a height of 120 ft. at Sandy Knolls and Rakaia, and to 110 ft. at Ashburton and Rangitata. One dozen lamps received from Messrs. Cooke, Troughton, and Sims during the year were a much-needed addition to the equipment in view of the fact that two observers are frequently observing simultaneously. It was found necessary to purchase four time-switches for fitting on these lamps." Minor Triangulation.—Some 225 square miles was completed at a cost of 225. per mile. These works were scattered areas, each being required for some special purpose. Topographical.—For developmental purposes some 30,000 acres have been topographically surveyed by ground methods, principally in the Auckland district. At Onekaka work is still proceeding on an area of 560 acres for town and works site, the mapping being on a large scale with contours at vertical intervals of 5 ft. On the national series of topographical maps made from aerial photographs, an area of 2,100 square miles has been photographed, while 1,100 square miles have been mapped. Until further instrumental equipment is available, a large proportion of the work has been done by plane table combined with the photographs. Orders for equipment were being placed, but owing to the outbreak of war these were cancelled. Standard, Surveys.—Very little of this work has been done during the year. The rural surveys, comprising 12 miles in the Gisborne, Hawke's Bay, and Wellington districts, cost £25 per mile, and the city work (30J miles in Dunedin) £43 per mile. Maintenance-costs on these and other basic control surveys amounted to £1,700. Precise Levelling.—Work on this was interrupted by more urgent surveys being required, but 81 miles of double levelling was run in Canterbury at a cost of £12 ss. lid. per mile. Rural Surveys. —A total'of 87,932 acres are returned under this heading, the average cost being Is. 4d. an acre. Native Surveys.—A total of 12,321 acres is returned as having been carried out under direct instructions from this Department, the cost being Is. 4d. per acre. There were also done by private arrangement 6,320 acres, the cost not being available. Town and Suburban Surveys. —-Two hundred and five sections of suburban lands averaging 6J acres each are returned for the year, the average cost being £9 16s. per section. Two hundred and one town lots were laid off at an average cost of £4 15s. per lot. Housing. —1,708 building lots were laid off for the year, the average cost per lot being £2 14s, per lot, and preliminary surveys over an area of 839 acres were made at a cost of £1,318.

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