HALL 80. 
WEST DOME. 
Beneath the center of the dome stands a statistical column, 
giving the bulk of each product of the mines of the United States 
in 1892, for one second of time. Multiplying this by the number 
of seconds in the year (3,536,000) will give the annual product. 
This column was built according to data given by the United 
States Geological Survey. In the four niches are pyramids of ore, 
containing: No. i — Gold and Silver Ores: No. 2 — Tin Ore: No. 3 — 
Iron Ore: No. 4— Copper Ores. 
The four large specimens surrounding the column are respect- 
ively: No. 5— Smithsonite (carbonate of zinc): No. 6— Silver Ore: 
No. 7— Iron ore (red hematite): No. 8— Iron Pyrite (sulphide of 
iron). 
