310 PROCEEDINGS OF SECTION B. 
few instances lodes pass from the granite into the shales above, 
and become richer and larger and less siliceous. The most pro- 
ductive lodes worked hitherto occur at the contact of the diorite 
dykes with the shales. 
The plant erected at Rivertree was designed by the writer and 
built under the superintendence of Mr.'T. Eyre in 1892. 
Advantage was taken of the fall of the ground to arrange it in 
three divisions :— 
I. Rockbreaker and sampler. 
II. Crushing and roasting mill. 
III. Leaching mill. 
I. The first division was placed near the mine, and comprised :— 
1. Ore receiving bins. 
2, Giant rockbreaker (Blake type), 15 in. x 9 in., driven by 
a 10 h.-p. Junior Westinghouse engine. 
3. Crushed ore bins beneath the rockbreaker. 
Immediately beneath the rockbreaker jaws, an automatic sampler, 
driven from the rockbreaker shaft, was fixed, which diverted at 
intervals the whole stream of ore to a sampling floor. About 5 
per cent. of the ore was so diverted. The rockbreaker jaws were 
set to open 1 inch only at the bottom. The whole of the ore 
passed through the rockbreaker. From the bins beneath the rock- 
breaker and sampler the crushed ore was taken by tramway to 
the drying floor in Division IT. 
If. The crushing and roasting mill comprised :— 
. The drying floor. 
One pair Wall’s corrugated rolls. 
One pair smooth-faced rolls. 
Two revolving screens. 
Two elevators. 
. Fine-ore bins. 
. White-Howell roaster. 
. Cooling floor. 
35 h.-p. standard Westinghouse engine. 
10. 52 h.-p. Babeock and Wilcox steam boiler. 
The drying floor (30 feet x 24 feet) was formed of cast-iron 
plates over flues, which acted also as dust chambers for the roaster. 
The roaster was 25 feet long by 4 feet 4 inches diameter at inlet 
end, and 5 feet 6 inches at outlet, and was driven by a small 2 h.-p. 
engine. A large chamber to catch the coarse dust intervened 
between the roaster and the drying floor. Midway in each flue a 
movable sheet-iron partition, 1 foot high, was placed across the 
floor. The feed-pipe of the roaster was furnished with a sheet- 
iron shield, reaching and fitting closely to the bottom of the 
cylinder, for the purpose of protecting the fallen ore-stream from 
the draught. These devices proved very effective. 
£2 0D I> STB Go ko 
