16 Scientific Proceedings, Royal Dublin Society. 
on account of the sinking being made in the reef proper, 
thus always being in touch with the reef, giving all necessary 
data as to value per ton thickness of reef. The ore won in 
sinking on the incline is afterwards profitably treated by the 
“reduction plant,’ whereas in the vertical system, the rock 
taken out consists only of the country quartzite, which is valueless. 
The cost in either case is practically about the same. It is now 
the rule to sink the inclined shaft in the Main-reef leader or 
middle reef, 7.e. in the body of the series. 
Deep-level Shafts.—It may be advisable to define the term 
“‘ deep-level.”’” The reefs dip in a southerly direction. The out- 
crop, as the word implies, is that part of the ore-body which is 
exposed at the surface, the ore-body being inclined and dipping to 
the south; the further south claims are held, the greater vertical 
sinking is needed to strike the reef. Data regarding the depth at 
which the reef should be struck depend upon the dip of the reef 
and the extent of the claims held by the outcrop Company south 
of the outcrop. 
A claim consists of 60,000 square (Cape) feet,’ equal to 400 
(Cape) feet measured along the outcrop, by 150 (Cape) feet at 
right angles to the same. The diagram on Plate 11. shows four 
claims on the dip, equal to 600 (Cape) feet measured at right 
angles to the outcrop. ‘The deep-level shaft would be sunk on 
claim No. 5. 
The vertical shaft is used to reach the reef in depth. When 
the reef is intersected, the shaft is continued on the inclina- 
tion of the reef. It is a very open question whether the shaft 
should be continued on the vertical, or follow the dip of the 
reef. In sinking on the reef as mentioned in the cases of outcrop 
properties, all data are obtained as to the value and thickness of 
the reef, which could not be furnished by a vertical shaft in barren 
ground. On the other hand, the wear and tear on the vertical 
system is much less than that on the inclined. The turning point 
(that is to say, the point where the vertical branches into the in- 
cline) is a source of trouble and loss of time, as it becomes necessary 
to slow down the hauling engines, on arrival at the point mentioned. 
The dip of the deep levels varies from 20° to 30° from the horizontal. 
11083 English feet equal 1000 Cape feet. 
