CO885-(18-19) — Page 285

PUBLIC RECORD OFFICE

Reference :-

mim C.O.885

18 PUBLIC RECORD OFFICE, LONDON

ALLY WITHOUT PERMISSION OF THE BE REPRODUCED PHOTOGRAPHIC- COPYRIGHT PHOTOGRAPH-NOT TO

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the plan, and may neglect to trace it to its source, thus leaving his work incomplete. At the same time it is obviously undesirable to survey the same features twice over, so that such items as roads, always completely surveyed upon the block plans, may well be taken. Streams or rivers may also be taken, with the above limitation clearly understood, but beyond these features there is little in the large scale plans of use to the topographer.

The tertiary triangulation points, or check poles, as well as the main circuit traverse pickets fixed by the block survey parties should invariably be used by the topographers, and vice versa, the topographical triangulators should take care that their points are marked with sufficient permanence to be available for the block survey Hitherto, there has been a wasteful amount of duplication in this work, partly from points being carelessly marked and thus lost, and partly from a mutual tendency to decry each other's work on the part of both the block survey and the topographical branches, each side affecting that the fixations by the other are not good enough for their work. It is not necessary to point out that the triangulation executed by either should be, and, in fact, probably is, amply good enough as the basis for both classes of survey.

It now remains to form an estimate of the cost of the 1-inch map of Ceylon in the new style. Assuming the normal strength of the topographical branch as:-

1 Superintendent,

2 Assistant Superintendents (triangulators),

3 Plane-table parties each of

1 Assistant Superintendent,

2 Grade Surveyors,

8 Junior Surveyors.

The annual cost will be:--

Pay

Travelling and horse allowances Cooly pay

Instruments and stationery, say

Total

Rs. 70,530

9,915

48,055

1,500

Rs. 130,000

Such a branch would maintain 24 plane-tablers in the field who in a seven-months' field season, working at the rate of not less than two square miles per man per week, should complete from 1,500 to 1,800 square miles of survey. The cost per square mile, will, therefore, work out to between 72 and 87 rupees, £5 to £6, a not excessive amount for the class of work considering the comparatively high cost of labour in Ceylon. Cooly hire, for instance, is nearly three times what it would be in India, and the pay of the Junior Surveyors is also substantially higher. Adding Rs. 7 per mile for the reproduction by copper-plate engraving, and assuming a mean cost for the survey of Rs. 83, the final cost of the finished 1-inch map of Ceylon will be Rs. 90 per mile, a total for the whole Island of Rs. 2,250,000 spread over 17 years. Owing to the difficulty of the levels, and the backward state of the detailed triangulation, it will probably be impossible to accomplish more than half the normal output of work during the next field season, 1907-8. After that the finished 1-inch map should be produced at the rate of five or six sheets per annum.

These estimates are based upon the supposition that the whole of the topo- graphical staff is continuously employed upon its legitimate work, and not taken away to make application surveys for rubber lands or other purposes, as has been the case in the past. It is sincerely to be hoped that the necessity for this wasteful procedure will not arise again.

Revenue Surveys. The revenue or large-scale surveys for land administration rrposes executed in Ceylon are of three classes:-

(a) Application and special question surveys for the determination of the areas and positions of parcels of Crown land which it is intended to lease or offer for sale by public auction either on the initiative of a private applicant or of the Government Agent; and for the settlement of special questions, such as reported encroachments upon Crown property.

Block surveys carried systematically over large areas showing the main

features, and the boundaries of all cultivation.

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(c) Cadastral surveys, either town plans or plans of irrigable areas under tanks, showing the features and all cultivation and ownership boundaries.

Up to the year 1897 the Department was practically an application Survey Department only, and all the work was done in isolated patches, often unconnected by any skeleton of triangulation, and quite incapable of combination into a general cadastre of the country. The cost of work carried out in this piecemeal fashion was naturally excessive, and the total outturn was small. In that year, partly owing to the recommendations of Sir T. Holdich and partly to the absolute necessity for a more systematic scheme of survey imposed by the passing of the Waste Lands Ordinance, the block survey was taken up. Unfortunately, the early attempts at this class of work were not altogether successful. Firstly, the scale adopted- 8 chains to 1 inch, or 10 inches to 1 mile, was not large enough to show all the detail required for land settlement purposes; and, secondly, the limits of error within which the surveyors worked were not fixed close enough, which fact, com- bined with imperfect supervision in the field, led to much inaccurate and unreliable work. Thus, while many of these 8-chain plans are of a satisfactory order of precision, others are by no means so, and give immense trouble when required for settlement, or for making further demarcations and sub-divisions of plots. Such work can generally be converted into satisfactory plans by replotting upon double the original scale, but the enormous labour of carrying this out precludes its adoption for any but isolated sheets.

For the last two years all the block survey has been done upon the 4-chain scale, 20 inches to 1 mile. The technical methods employed are as follows:-A terti- ary triangulation is made, fixing a number of points (check poles) within the area. These are generally fixed by three intersections from primary or secondary points. Main circuit traverses are run through and across the country, departing These are carried out with from and closing upon triangulation points.

5-inch theodolites and steel tapes, and the limit of closing error is set at 3 links in one mile (1 part in 2,700). They are computed by coordinates These main-circuit traverses are generally spaced at such intervals that each sheet of the 4-chain plan contains one traverse line through it, but in some cases they have been spaced at about double this interval, and connected by minor traverses, also computed by coordinates, with a limiting error of 4 links in one mile (1 part in 2,000). Stone pickets, set in concrete blocks, are placed at intervals along the traverse lines, and their positions are carefully recorded in ledgers.

The detail survey is then made by traversing with 4-inch theodolite, chain, and offset rods, the field work being recorded in a traverse book of the Ordnance survey pattern. These detail traverses are closed upon the check poles or the pickets fixed by the main circuits, and the accuracy of closing is checked by the officer in charge of the party. The plotting is done by protractor and scale. Each man plots his own work, and the line plotting is not allowed to be in arrear of the field work by more than a week. The detail plotting, finishing, and colouring the plan, computing the areas and compiling the tenement lists or schedules of owners, is done in recess.

There is no doubt that in the case of the 4-chain work, now and for the last two years in progress, the resulting plan is thoroughly accurate and complete, and is perfectly suitable for the fixation upon it of further details required, either for application work or for such demarcations and subdivisions as are demanded by the Settlement Officer under the Waste Lands Ordinance.

The technical methods are well suited to the country, and to the capacities of the survey staff. No alteration in them is recommended. Two points, however, call for special mention. It will have been observed, in the above description, that the surveyor plots his own work, a practice contrary to that of many Survey Depart- ments. It is argued, with some show of reason, that errors are more readily detected and the danger of " fudging" minimised if the field work and plotting are separated. It is extremely doubtful whether it would be judicious to introduce this system into Ceylon. It would probably delay the work, thus increasing the cost, but, beyond this, the real objection to it lies in the fact that it would tend to foster ill- feeling and give rise to undesirable quarrels between members of the staff. A similar difficulty has already been mentioned in relation to the question of the

promo- tion of native surveyors.

A native member of the staff may be perfectly ready

to accept reproof from the head of his party or from the Superintendent, but he

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