Thus a number of rivers were surveyed--the Maria, Tucuti, Yovisa and other tributaries of the Tuyra. When it was found that a sufficiently correct idea of the country for topographical purposes could not be obtained by simply meandering the water courses, lines or _trochas_ were cut through the forest from stream to stream, and where two streams thus connected were tributaries of a common river, all of which had been previously surveyed, a closed figure was obtained, an adjustment for errors of closure made, and by putting together the topographical data obtained by the four lines, there was generally found to be sufficient information to give a satisfactory though of course a crude delineation of the included area. After a number of rivers had been examined with more or less accuracy in this way, it was finally decided that the area for one portion of the grant best suited for the purposes of the Canal Company lay on the right bank of the Tuyra river, and that the portion of the river which lay between the mouths of two of its tributaries, the Rio Yape and the Rio Pucro, should be one of the boundaries of the grant. The Yape and Pucro have courses approximately parallel to each other and at right angles to the Rio Tuyra, and these streams were also chosen as boundary lines, so that the grant would have the three rivers as natural boundaries, and the fourth and closing boundary was to be a straight line from a certain point on the Yape to the Pucro, so located as to include within the four boundaries an area approximately equal to the amount of the grant, which in this particular case was 25,000 hectares. The problem then presented was: given three rivers for three boundaries of a figure to establish a fourth and artificial line, completing the figure in such a way that it should contain a given area, and also to procure data for a topographical map of the country surveyed. This survey was put under my direction and I was instructed to proceed to a point overlooking the Tuyra river, between the Rio Yape and the Rio Pucro, near the mouth of the Rio Capite, for the purpose of establishing a base camp. Leaving Real de St. Marie on the evening of March 15th, with a fleet of twelve canoes and about thirty native laborers, we reached the site for the camp in two days. After landing everything, the work of clearing away trees and underbrush over an area sufficiently large for the camp was commenced. The men worked willingly with axe and machéte, and soon the forest receded and left bare a semi-circular space facing the river.