Page 2 Advertisements Column 4

Wellington Independent, Volume XXIV, Issue 2812, 20 March 1869, Page 2

10 Chains to an inch for blocks from 1000 to 5000 acres. 20 Chains to an inch for blocks above 5000 acres. For District Maps, 40 Chains to an inch. For General Maps, 80 Chains to an inch. Plotting. 67. The plans are to be drawn upon mounted paper which should not be cut less than two feet square. Having set off meridian and perpendicular lines 50 or 100 chains apart according to the scale adopted (see paragraph 37) proceed to lay down the principal points from their computed meridional co-ordinates and then to plot in the intervening work with the ordinance card protractor. All lines drawn upon the plans are to have their bearings and distances legibly written upon them when possible to do so without crowding, otherwise a table shewing this data is to be inserted in the blank space of the paper (see Appendix). Type of writing on the Plans. 68. The style of writing upon the plans should be plain, neat, and tending more towards general utility and saving of time and labour than to pictorial and elaborate effects. The size of the letters should be strictly proportionate to that of the plan; the most conspicuous characters are to be used for names of the first order whilst the lesser characters indicate those of smaller importance (see Appendix). The bulk of the writing should lie parallel with the top and bottom of the plan; curved lines are preferable for names of Districts, Blocks, Mountain Ranges, Rivers and Streams, but in no case should the writing appear upside down on the plan. Opposite Corners of Roads. 69. A road line running by stages on different directions requires that the variations in length of its opposite sides for every succeeding stage should be computed in terms of the known angle that the new stage makes with the preceding one. A straight line drawn between any two opposite corners of a road bisects the angle included between the stages at those points, and consequently the bearing of this line is known. Again the distance between the opposite corners is readily obtained by inspection from a Table of Natural Tangents and Secants, being equal to the cosecant of half the included angle above alluded to; also the difference in length between the opposite sides of the road to these points is equal to the cotangent of the same angle. For example: suppose the stages of a road 100 links wide run in directions bearing 25° and 155° then the included angle is 130° and the bearing from corner to corner opposite is 90°. Now, by reference to a Table, the Natural Cosecant and Cotangent of 65° or one half the included angle to Radius 100 is 110.3 links and 46.0 Iinks respectively, the first indicating the distance between the opposite corners and the second what one side of the road is longer than the other to these points. By successive computations for every angle that the road makes the total lengths of the opposite sides for every stage becomes known, which is very important where sections front upon tortuous road lines. The opposite corners of cross roads are determined in the same manner. Notwithstanding the very simple manner by which these dimensions for opposite sides of roads are obtained, they have frequently been stated in impossible quantities on the Maps, thus betokening on the part of the Surveyor either a wilful neglect or a gross ignorance of the first principles of Geometry. Computing Book. 70. The computations of a survey are to be kept in a book for the purpose and to accompany the plan when forwarded to the office of the Chief Surveyor. The writing of the figures must be clear and the statements methodically arranged so as to exclude all doubt in the mind of a second person who may have to recompute the work; besides neatness and order materially conduce to the accurate and expeditious working of any elaborate calculations. Difficulties met within a Survey and not provided for in these instructions to be dealt with by the Surveyor or by reference to Chief Surveyor. 71. As it is utterly impossible by written instructions alone to impart to the Surveyor a thorough knowledge of the various and often complex duties required to be performed or to provide for all contingencies that arise in the progress of actual operations, much must necessarily be left to his intelligence and discretion, and when difficulties are encountered which he is unable to overcome an immediate report detailing the circumstances should be made to the Chief Surveyor. Concluding Remarks. 72. Lastly the Surveyor should endeavour by a careful study of the Standard works on Surveying to make himself thoroughly acquainted with not only the minor but also the higher branches of the profession and this combined with industry and zeal in the performance of his public duties will acquire for him a high professional reputation and the respect of his employers. GENERAL MEMORANDA. Returns and Vouchers. The following Returns and Vouchers are to be forwarded to the Survey Office by each officer of the Staff. Monthly: Abstract of labourers' wages; voucher for contingent expenses; journal of work; report on the general progress of the Survey. Quarterly: Vouchers for field and instrument allowances. Annual: Return specifying the nature and quantity of work performed by the Surveyor in each District or Block, and the cost of the separate surveys. Hours for Work. The hours for work whilst in the field are from 8 a.m. to 5 p.m. during summer months, and from 8.30 a.m. to 4 p.m. during winter. Trigonometrical stations to be repaired when requisite. The trigonometrical stations and other important survey marks when visited by a Surveyor should be repaired if found to be out of order.