The Mount Morgan ore body is intersected by dykes to such an extent that it presents peculiarly difficult problems in extracting the ore. These are shown on Plates Nos. II. and III. Besides these dykes there are innumerable "heads," which also are a source of danger. Falls of ore occurred in the end of the year 1908, resulting in serious loss of life to miners employed. It was decided, after an exhaustive inquiry, to change the entire system of mining from the " flat backed stope system " to the " square set sectional system ," the latter being more flexible and allowing bad ground to be cut out from a safe position ; but it became evident that, whatever system was adopted, there would be more or less danger unless all the dykes and heads known were picked up, and their continuation plotted on a special set of plans on which the general scheme of stoping could be plotted from time to time as work progressed. It is worth while pointing out that, in every other branch of engineering, it is usual to design the work, and that only in mining engineering has it been common to do the work first and plot it down afterwards.