"The silver mines of Peru," said he, "are yielding very little at present, owing to bad management and slovenly methods, and the same is the case with the mines of Bolivia. During the last two and a half centuries the mines of Peru alone have yielded five hundred million dollars worth of silver; the mines near Puno are famous in history, and are enormously rich, but for a long time little has been done beyond reducing by modern processes the refuse of the old miners. When the country becomes tranquil, and capital can be securely invested, the mines will be reopened, American and other machinery introduced, and the world can again be supplied with silver from the Andes. "Potosi, in Bolivia, is probably the richest silver region of South America and of the whole world, but its mines are now almost neglected. In the seventeenth century the city had more than a hundred thousand inhabitants, while it has barely twenty-five thousand to-day. Between 1545 and 1789 the mines of Potosi yielded one thousand million dollars' worth of silver, but of late years the product has not exceeded two and a half millions annually. The word 'Potosi' signifies 'an eruption of silver,' and the place is certainly well named. It is in a province of the same name, which produces also gold, copper, iron, lead, tin, quicksilver, zinc, antimony, and other minerals, but silver is its principal yield. [Illustration: SECTION OF A SILVER MINE.] "Potosi suffers for lack of modern methods, as much as do the mines of Peru and other South American countries; nearly all the mining is done by Indians, who adhere to the processes that have been in use for centuries; the spirit of enterprise does not prevail here, and until it does there will be no revival of the business." One of the youths asked a question which led to a description of the primitive ways of mining at Potosi. [Illustration: A PRIMITIVE MILL.] "Take, for example," said their entertainer, "the mill in which the ores are crushed. It is a rude affair, with two wheels of stone at the end of a horizontal bar moved by an upright shaft. The propelling force is an ox, a mule, or possibly a stream of water, and sometimes the mill is worked by the power of men. The apparatus somewhat resembles an old-fashioned cider-mill in the Northern States of America, but the roughest cider-mill you ever saw is a piece of cabinet-maker's work compared with a Bolivian _arastra_. The broken ore is placed in a trough in which the stone wheels move slowly around, crushing, perhaps, half a ton of ore daily. Modern mills, such as are used by the miners of California and Nevada, would crush twenty times as much ore at little more than the same cost! [Illustration: ARASTRA, WITH MULE-POWER.]