Underground traverses

Surveying in a mine is a process of traversing. The line of traverse is often run so that the longest possible sight maybe taken. After the main traverses have been run, the surface boundaries may be established accurately underground and the stopes and working places surveyed by more convenient and less accurate methods, from the traverse stations already established.

Accurate traverses should be carried into all important workings of the mine. These include the shafts, levels, cross cuts, raises and winzes. Permanent transit points should bf established in the shaft at every level; in an inclined shaft it is a good practice to put in one or two points on the line-between the levels to hold the direction of the shaft.

Offset distances called "rights" and "lefts" are measured on each side of the traverse line within the mine workings for the purpose of locating the limits of the workings.

The floor of passages is defined by determining the ele­vation of the necessary number of points, and the roof—by rneasurements from points located on the floor. Elevations are defined within the mine either by direct levelling, as in level­ling out on the surface, or by means of inclined distances and vertical angles.

The planning of a modern colliery presents problems which call for great knowledge of mining. This work is done by designing engineers who are engaged in planning the colliery as well as in estimating the output of the mine in the future.

The factors to be estimated are: the existence, depth, thickness, inclination and character of the seams to be worked.