22
Thesefigures will be given only for the main framework. There will remain a number of subsidiary Trigonometrical stations and a large number of dependent traverses. They must be put in sympathy with the new values, or confusion and error will become worse ather than better. There will remain to be done then :—
(f) A recomendation of minor triangulation.
(g) A readjustment of traverses.
For both of these measures the original computations could be used if corrected from the new lengths, bearings, and positions. If so, however, a careful statement of procedure should be prepared and printed with the new values.
The final record should not include any points which are no longer to be found on the ground, or any which are not lixed with sufficient accuracy. For example, Lieutenant Wace's points should not be included unless they still exist, and have been recomputed to agree with new values. The War Office should be consulted on this point.
The area dealt with is, of course, small, and the staff is mainly concentrated. To these facts perhaps is due the absence of any departmental and technical regulations. Thus the exact procedure to follow (so important with local staffs) is nowhere laid down. I do not desire to criticize the staff or its work. As a matter of fact I sec evidence of hard work and honest purpose. Like most other survey matters here, however, the edge is blunted by lack of ordinary technical tidiness in method, com- putation, and record. Thus in the case of traverses I found evidence of good work. but no check upon bearings and no analysis of error in the form indispensable to quick understanding and check by the directing officer.
It is, for example, impossible to deal properly with horizontal angles whose field records do not specify are (or zero), face (or circle), and swing. It is equally in- adequate to record elevation or depression (from the horizontal) indifferently as the angle itself or its complement. No surveyor should be sent to work without a clear idea of the precision expected. I will revert to these proposed regulations later.
The question of proper forms both for computation and for record should be studied. Survey computations," published by the War Office (His Majesty's Stationery Office, 1928), will help here (although the traverse forms may be hardly suitable). The final records of triangulation and traverse are of three distinct sorts:—
(1) Records of field measurement;
(2) Records of computation;
(3) Records of finally adopted data and positions.
As far as possible these three should be distinct, and complete for their own aspect.
Before dismissing the subject it is important to remember that records cannot be kept unless there is a staff to compile them and suitable accessible storage room in which to house them. All survey records (plans and maps, as well as triangulation or framework) should be in the hands of one man--and that man is obviously he who is responsible for the survey.
Directly the new values have become general and are adopted for daily routine all other, and now obsolete, records (as for example those of Mr. Newland) should be collected and destroyed. There is no point in keeping a record of points which are no longer recoverable on the ground. An exception to this may lie in the positions of some of the traverse stations in Paddy and other rural areas, where they can be identified on the 32-inch plans.
It will be obvious that I am recommending an amount of analysis, recomputation, and rearrangement impossible to the existing staff. I am convinced, however, that it is vitally necessary, and shall make recommendation elsewhere accordingly. I also recommend that for the mass of minor co-ordinate computation machines should be introduced. The new Brunsviga is a satisfactory machine. Its use and the various tables and records necessary can be studied either at home, or. by arrangement, at the Headquarters of the Federated Malay States Survey at Kuala Lumpur.
7. Topographical Surveying. Actually the present Survey Department has not been concerned with topographical mapping. The muddle which exists at the present is none of its business, but is due to the publication of various surveys, done at different times and disagreeing with each other and with the ground.
There are the 8-inch (Hong Kong and part of New Territories) and the 2-inch printed by the Ordnance Survey, the 24-inch and 3-inch printed at the War Office. and there is also the unpublished 2-inch plane-table survey by Turner and Johnston. So unsatisfactory was the position for defence purposes that the Air Ministry and the War Office agreed to photograph and survey respectively, in order to bring out a thoroughly reliable 3-inch (1/20,000) map.
There will be 24 sheets of this map, and the present position is as follows:-
Published
Eurveyed and being drawn
Being surveyed (half done)
12
7 on 10th February, 1930. 5
The series will be really reliable but can only illustrate the development at the date of photography (1924). The War Office is, I understand, to follow up with a good 1/100,000 (roughly 3-inch) map showing the whole area.
As soon as the 1/20,000 and the 1/100,000 are complete, all previous maps should be withdrawn and destroyed.
I do not think so
The 8-inch шар is a possible exception to this statement. because the 8-inch seems to serve no real purpose save that of a diagram of the larger revenue sheets. For such purposes the 1/20,000 will do just as well, but the point should be considered by the Survey and Land Departments affected.
From the Government point of view it is important to make arrangements with the War Office for a sufficient number of copies to be supplied for issue to officials and, for the benefit of the non-official engineer and industrialist, to see that sufficient stocks are kept for sale in the hands of a map agent.
Once made, this topographical series should be kept periodically revised. Revision can be effected-
(a) From air-photographs,
(b) From ground survey,
and of these the former is probably the best in so far as photographs are available. No doubt the Royal Air Force will be able to provide some photographs, and the Survey Department should keep a record of them, and forward copies to the War Office, through Command Headquarters with a diagram to call attention to the altera tions desirable. Where photographs are not available, alterations and additions should be shown (on record sheets) from either the new revenue survey or from plane-table survey. It is most important that the record sheets should be most carefully prepared and should be fully explanatory of "deletions" as well as of additions. These have to be understood and carried out by draughtsmen in England. To avoid unnecessary correspondence and delay absolute clearness is essential. Some alteration to the sheets of the Island and Kowloon is already required. There are also some new roads important to defence, which should be inserted as soon as possible. In future five years might elapse before revisions in urban districts and a longer interval in other
cases.
The War Office has already spent large sums on this survey and in the adjustment of the triangulation. It is but fair to envisage payment for alteration in the future. A close touch should, therefore, be maintained between Civil and Military Depart- ments, and the Director of Survey should be in frequent, direct, and personal com- muniction with the Geographical Section of the General Staff.
I must once more emphasize the essential point that a survey must not be allowed to get so out of date as to necessitate complete renewal. It will rest mainly with the local Survey Department to see that this point is remembered.
There is too a W.D. 1/10,000 map of Victoria and Kowloon. Already slightly out of date this map might be of the greatest use to the Colony, if extended slightly to the west and considerably to the north. I should like, too, to see roads on the Peak emphasized, and some of the houses on the Peak numbered. The result would be a large, but still quite a possible, sheet. Its value would be enormously greater than that of the incomplete sheet now produced. The Colony should provide the photo- graphs and pay for the cost of this enlargement of area, and the question should be discussed now with the War Office. It should he pointed out that the purpose to be served is to include all the present area of intensive urban development, and that this is possible on one sheet. The extension should include square (500m.) both east and west and 2 squares (2,000m.) north.
"Official use only."
Such a map should have a ready sale, should not be marked and might be highly priced (say seven to ten dollars)
Eventually the Survey Department should be in a position to take over all maps of the Colony, to revise them, to print further editions, and to sell to the public. To sell efficiently implies an accessible map sales office and efficient advertising (placards, gazette, and newspaper notices, &c.).
8. Lerelling.--In Hong Kong and the New Territories the dimension of height assinnes peculiar importance. A control of reliable levelling is, therefore, essential, and a good start has been made. The fundamental benchmarks are satisfactory. The problems now in front of the levelling are the analysis of tide gauge records, to provide A proper datum, and the reduction and adjustment of levelling ligures. The proper
23
No comments yet.
Private notes are available after approval.