At present the richest gold field in the world is that of South Africa, which yielded in 1910 a value of $175,000,000, somewhat exceeding the combined yield of the United States and Australia. Russia and Mexico followed these in yield. The total production throughout the world amounted to over $450,000,000, of which the United States produced $96,000,000.
What are Cyclones?
A cyclone is a circular or rotatory storm, or system of winds, varying from 50 to 500 miles in diameter, revolving around a center, which advances at a rate that may be as high as forty miles an hour, and towards which the winds tend.
Cyclones of greatest violence occur within the tropics, and they revolve in opposite directions in the two hemispheres—in the southern with, and in the northern against, the hands of a watch—in consequence of which, and the progression of the center, the strength of the storm in the northern hemisphere is greater on the south of the line of progression and smaller on the north than it would if the center were stationary, the case being reversed in the southern hemisphere.
An anti-cyclone is a storm of opposite character, the general tendency of the winds in it being away from the center, while it also shifts within comparatively small limits. Cyclones are preceded by a singular calm and a great fall of the barometer.
What Metals can be Drawn into Wire Best?
The wire-drawing of metals depends on the property of solid bodies, which renders them capable of being extended without any separation of their parts, while their thickness is diminished. This property is called “ductility.”
The following is nearly the order of ductility of the metals which possess the property in the highest degree, that of the first mentioned being the greatest: gold, silver, platinum, iron, copper, zinc, tin, lead, nickel, palladium, cadmium.
Dr. Wollaston succeeded in obtaining a wire of platinum only 1⁄30000th of an inch in diameter. The ductility of glass at high temperatures seems to be unlimited, while its flexibility increases in proportion to the fineness to which its threads are drawn.