THE paper sets out to examine the most effective way of applying methods of air survey to the interests of petroleum technologists. Following a statement of the inadequacy of the available maps of the British Empire and the consequent increasing need of surveys in all parts, stress is laid on the suitability of methods of air survey to tackle the present problem. To emphasise, however, its precise function, a very brief exposition of the essential stages of any regular survey is given, one stage of which can conveniently be replaced by using air photographs. The most important developments of the technique of air survey are treated in a broad manner, so that the applicability of a particular method to any given problem may be estimated, and the aim has been therefore to place the reader in possession of the elementary principles governing such a choice. Finally, the formation of a survey organisation on Imperial lines is discussed and its very real need stressed. Such an organisation, by co-ordinating interests and planning action on a big scale, would not only serve many interests at the same time, but would minister to each more efficiently than any sectarian solution. The men, the instruments, and the necessary skill and enthusiasm are available. Only the education of the financier is lacking.
. In a country like England, where, owing to the vision of our forefathers, accurate maps are available for almost any purpose, we are apt to forget the enormous amount of work necessary for their preparation and constant revision. Yet if we consider as a standard of survey a good map on a scale of 1100,000 or about 1 1 miles to the inch-a not very exacting standard in view of modern requirements-by far the greater part of the world is virtually unmapped, Maps are required for a variety of purposes, many of which can hardly be foreseen (e.g. the recent "gold rush" in Kenya), and their preparation must therefore be regarded as a fundamental branch of administration. At the present moment, Survey Departments in all parts of the Empire are being forced to cut down their work, with the result that not only is very little new survey being done, but existing maps are rapidly becoming out of date. Many examples. could be quoted of the penalties which are always paid later for'such negligence and lack of foresight, but the lessons of the past are at the present juncture just as unpopular as provision for the future, and it may be confidently expected that nothing will be done till the urgency of some particular question forces attention to the problem. At that date the immediate need will be for a method of survey which will enable the work to be carried out with minimum delay. It is this function which air survey is admirably suited to fulfil. Opinions on air survey vary from depreciation to devotion.