| Case I. | Deposits where topographic conditions permit
the alternatives of shaft or tunnel. |
| Case II. | Vertical or horizontal deposits, the only
practical means of attaining which is by a vertical
shaft. |
| Case III. | Inclined deposits to be worked from near the
surface. There are in such instances the alternatives of either
a vertical or an inclined shaft. |
| Case IV. | Inclined deposits which must be attacked in
depth, that is, deep-level projects. There are the alternatives
of a compound shaft or of a vertical shaft, and in some cases
of an incline from the surface. |