THE ORDNANCE SURVEY

Abstract

If, one and all in our several ways, we are absorbed in helping to win the war, there are moments when it is possible to turn to our earlier loves, if but to relieve the strain. Not one of our hobbies, not a single insti tu tion that holds our affections and our memories, can emerge from this struggle just as it was. New thoughts and new methods are in the air, new service will be required, and, if principles remain largely unaltered, they, and the lessons we have learned, will be in peril, for continuity and knowledge have been rudely interrupted. It may do no harm to restate, however inadequately, some of those lessons—political, administrative and technical.     

SURVEY IN THE GREAT WAR

Abstract

Artillery Survey.—Included in the term “Artillery Survey are two distinct problems, the first that of determining the “line” and “range” at which fire should be opened, and the second that of laying the gun in the required line. To appreciate these problems it. is necessary to know a little about the technique of gunnery, and for the benefit of those who have no acquaintance with the subject the following brief résumé may be given.     

THE ORDNAKCE SURVEY MAP-MOUNTING MACHINE

Abstract

The practice of issuing a certain proportion of each edition of small-scale maps mounted upon linen or other cloth is of long standing, and for many years there have been machines capable of mounting rolls of paper upon rolls of linen, the linen-backed product being finally cut up into sheets for printing.     

THE KEEPING OF SURVEY RECORDS

Abstract

Although the title of this paper may appear to some to refer to a rather humdrum subject which hardly deserves much serious thought or consideration, it is the writer's experience that the vital necessity for keeping clear records of survey work in a permanent form in which they can easily be referred to at any future time is not always sufficiently appreciated by those whose duties do not involve constant or frequent reference to the records of old work. Accordingly, the following notes and suggestions, which are based on practical experience, may be of service in drawing attention to a matter which is really of great practical importance.     

SURVEY IN THE GREAT WAR

Abstract

Hostile Battery Location.—Among the tactical ideas current in 1914 before the outbreak of war was the conception of an artillery duel as the opening phase of a great battle. This was pictured as a “hammer and tongs” sort of business in which the opposing artilleries were drawn up in full view of one another, and the winning assets were speed in coming into action, quicker rate of fire, and superior endurance. Good drill, in short, was thought to be worth much more than preliminary calculation. Actually, in the event, it was soon discovered that no battery could come into action in the open without being immediately destroyed. Far from there being any artillery duel, the opposing artilleries soon found themselves unable to attack one another at all. For a time, in the stress of greater happenings, this unforeseen development passed unnoticed, the reason being that the British artillery, having no shells to speak of, were compelled to keep the few they possessed for helping to repel the German infantry, while the German gunners, though they had plenty of ammunition, saw no reason to expend any of it in subduing an artillery which fired so seldom. Throughout 1915, until the shell shortage had been overcome, the recognized procedure for putting a stop to hostile shelling was to retaliate by a few rounds on some reputedly sensitive spot in the infantry trenches. History does not record the precise nature of the reactions in the hostile organism set up by this procedure nor whether it was invariably effective for the purpose in view. In any case no other procedure was possible because no one knew exactly where the hostile batteries were.     

THE SURVEY FRAMEWORK OF NIGERIA

Abstract

The vertical framework of Nigeria comprises a network of primary instrumental levels and trigonometrical heights. The primary levels consist at present of (1) a network in the South-western Provinces, (2) a continuous line of levels from Lagos through Ibadan, Ilesha, Akure, Benin, Onitsha, Awka, Okigwi, Aba, and Port Harcourt to Bende in Calabar Province, and (3) a further line from Ilesha to Oshogbo and thence along the railway to Minna, where it is connected to L41, the south terminal of the Minna base. The total mileage of double levelling is 1,128 miles. Trigonometrical heights have been determined by reciprocal observations over all the primary chains.     

AIR SURVEY AND THE PHOTOGRAPH

Abstract

As air-photographs are being more and more used for survey purposes, Empire surveyors who have not yet made a thorough study of aerial survey may be interested in a little elementary photographic geometry and its application to map-making. A map may be described as an orthogonal proj ection of the ground upon a horizontal plane, reduced to some convenient scale, and a photograph as a conical projection of the ground upon the focal plane of the camera. If the focal plane is horizontal at the instant of exposure and the ground being photographed is perfectly level, the two projections are exactly similar and the photograph is indeed a map. Unfortunately these conditions which are illustrated in fig. 1 are extremely rarely encountered, and photographs usually need correcting for various distortions.     

THE SURVEY FRAMEWORK OF NIGERIA

Abstract

Angular and Linear Errors.—In the results which follow, the number of stations quoted on the chains is exclusive of all the stations on the base-extension nets at Minna, Rijau, Chafe, and Naraguta. The total number of stations can therefore be obtained by adding the numbers on all the chains and the base-extension nets and deducting the number of points common to other chains. The quoted fractional misclosures in length are the actual misclosures obtained and the theoretical fractional misclosures which might be expected to be developed through the chains from the probable errors of the adjusted angles.     

THE SIERRA LEONE TOPOGRAPHICAL SURVEY

Abstract

The survey of Sierra Leone was fortunate enough to be completed just in time before the economic blizzard (if I may be permitted a well-worn journalistic cliché) descended on West Africa in common with the rest of the world and largely curtailed such activities. I do not propose to deal here with its technical side to any great extent. An excellent account of bush surveying is to be found in the “Handbook of the Southern Nigerian Survey”, which account always filled me with the greatest awe and respect for the men working there, their output being vastly greater than anything we were able to achieve in Sierra Leone. Truly “there were giants … in those days”.     

THE SURVEY FRAMEWORK OF NIGERIA

Abstract

At the Conference of Empire Survey Officers held in London in 1931, an historical sketch was given of the progress of triangulation in Nigeria from its commencement to the end of the 1930 season, together with a brief summary of the proposed future programme. Since that date substantial progress has been made, and the recent completion of several important chains of triangulation and of the main precise traverse framework through the thickly forested regions of the Southern Provinces seems a convenient opportunity to place on record the present position.     

THE GEODETIC SURVEY OF CANADA

Abstract

Shortly after the inception of the Geodetic Survey of Canada in 1905, reconnaissance for primary triangulation was commenced in the Ottawa-Montreal area. About the same time, precise levelliilg operations were begun from a bench mark already established by the United States Coast and Geodetic Survey near the International border at Rouses Point in Quebec.     

THE MILITARY SURVEY SERVICE AND THE CIVILIAN SURVEYOR

Abstract

When Colonel Lambton of Indian fame wanted funds for his Survey a leading melnber of the Finance Committee of Madras observed that “if any traveller wished to proceed to Seringapatam he need only say so to his palankeen bearer and he vouched he would find his way to that place without having recourse to Colonel Lambton's map”. Those who have had the privilege of dealing with finance branches will recognise in this quotation a powerful tradition and it is a measure both of the great march of events since Lambton's time and of the deterlnination of military surveyors not to lag behind them, in spite of finance committees, that good military maps are nowadays taken for granted and that the large survey organisations, required to produce them are accepted as a necessity. The struggle to maintain this position however goes on.     

THE CALIBRATION OF AERIAL SURVEY CAMERAS

Two experimental procedures for aerial survey camera calibration using respectively a Wild TA theodolite and a modified Cooke, Trough ton and Simms geodetic theodolite are described. The procedures determine radial distortion only; tangential distortion is assumed to be negligible. Details of a graphical method of computing the results are given in an appendix.