In the surveying and mapping of Canada, it is of prime importance that the surveys and the resultant maps should measure up to modern standards of accuracy. At the same time the cost of the surveys should be kept at a minimum. Where organisation is efficient and skilled personnel using modern instruments and methods are employed, the expense involved in conducting a survey of high accuracy need not greatly exceed the cost of less exacting operations. Moreover, the compensating advantages of an accurate survey more than offset the extra expense involved. Where suitable geodetic control‐points are used as a basis for the location of the topographical features and artificial developments throughout the country, the resultant map or chart may be made to comply with every requirement of accuracy and detail; and where suitable monuments are established in the field to perpetuate the control‐points of the survey it is a simple matter to return at any future time to locate or survey local improvements or developments. Where the original surveys of a large area are not based on accurately located points forming part of a nation‐wide scheme of geodetic control, the map of the district cannot be constructed within the limits of accuracy usually required, and as the needs of the country become more exacting in this respect it would be necessary, in all probability, to repeat the original surveys with the attendant expense and