ments to this work from the appropriation for forest surveys and from State funds for cooperative purposes, bringing the total to nearly $500,000. The expenditure upon this work since its inception in 1879 has been $6,672,000.

Pl. V shows the areas that have been covered by the topographic

surveys.

The results of the work of this division may be seen, also, by reference to the tables of atlas sheets and other maps in the Survey's list of publications.

Section of Triangulation and Computing.

Since the inception of topographic work by the Geological Survey, primary triangulation and primary traverse have been executed on an extensive scale. At first topographers were assigned to the work of observing astronomic positions, measuring base lines, or extending primary triangulation. They acted, however, under the direction of the chiefs of the topographic sections, and frequently, in addition to their work as triangulators, were in charge of parties making topographic surveys. Gradually, as individuals evinced special aptitude for this work they were assigned to it exclusively.

As the work of the topographic branch increased it became evident that the part thereof which consisted of field triangulation and office computation needed systematizing, and therefore, in 1894, when the topographic branch was reorganized, it was separated into two divisions--one of triangulation and another of topography. For a few years the actual administration of the triangulation division remained in the hands of the chiefs of topographic sections; but in January, 1897, in order to secure uniformity in the office work connected with this division, a chief computer was appointed, under whom all office computations were conducted. In 1903, upon a further reorganization of the topographic branch, the division of triangulation was abolished and all the work of triangulation and computing was segregated in a section, the chief of which is in administrative charge of office computing. But, for convenience, the triangulation field work continues to be administered by the topographic section chiefs. During the last three years, however, the chief of the section of triangulation and computing has been in immediate charge of the field work of triangulation in the eastern section, under the direction of its chief.

For several years after the enactment of the law of 1896, authorizing and directing the running of careful spirit levels in connection with the topographic mapping, the office reduction and computation of results remained in the hands of the topographic chiefs. Gradually, as the work expanded, it became evident that for proper organization and supervision it should be made a separate section, and in 1901 the chief of the section of triangulation and computing was called upon to