Page:Popular Science Monthly Volume 50.djvu/700

680 grown to be a city of a hundred thousand inhabitants, with modern features, and Manáos, up the river, is fast following it. India rubber is the mainstay of the northern Brazilian states, Bolivia, and eastern Peru. Brazil has a great advantage in its immense waterway; ocean-going steamers run twelve hundred miles up the Amazon, whereas every African river except the Congo has a bar at its mouth and cataracts not far distant from the coast line. It is, besides ivory, about the only commodity produced in the interior of a tropical country that will bear the expense of transportation, often on the heads of natives along tangled man-paths, to the seaboard. So in many places it has been the basis of first commerce. The principal trees in South America are the Manihot Glaziovii, the Ficus gameleira, and varieties of the Castilloa, the Hevea, and the Hancornia. "The production of Pará rubber," says the Scientific American, December 5, 1896, "increased from 8,243,000 pounds in 1865, to 15,144,000 in 1875, 29,310,000 in 1885, and 46,363,000 pounds in 1895; the great advance in the decade between 1885 and 1895 being the direct result of the increased demand produced by the tire-makers. Last year 37,456,000 pounds were delivered to manufacturers in the United States, against 31,062,000 pounds in 1894 and 35,583,000 pounds in 1893. The highest price paid in this country last year for fine Para rubber was eighty-one cents and a half in November." The United States has been from the first the largest consumer, and an American syndicate, it is said, is now seeking capital to develop ten million acres in the Orinoco Valley, chiefly with a view to profits from the great virgin rubber forests known to exist there.

Enormous supplies are stored up in Africa and her adjacent islands, where a variety of Ficus and great climbing shrubs, the Landolphia and Vahea, produce it. Stanley alludes to great numbers of these climbers entwining the trees, so as to make passage exceedingly troublesome. Attempts to force the price to unreasonable limits are therefore not likely to meet with permanent success, and we may banish fears of approaching exhaustion. The gum fully thrives, seemingly, nowhere but in the tropics. "It is the one jungle product which society finds indispensable," said The Spectator recently, and, further: "Everybody knows that in the last five years the use of pneumatic tires for cycles and solid rubber tires for horse-vehicles has enormously increased our consumption of this article; but, quite apart from that more obvious fact, India rubber is daily being introduced more and more into all sorts of machinery. Highly competent judges say that if the output could be doubled within a year, so many applications would instantly arise that the price would not fall appreciably." The negroes have no regard for the climbers, and cut them down in order to extract the utmost possible amount of sap.