In the United States the consequences were far more serious. The invention of the engine or "gin" for separating the lint from the seed made cotton cultivation highly profitable.[31] The negro slaves, who had been scattered throughout the colonies and the States that succeeded them, were soon drawn to the cotton-growing States to supply the needed field-labor; and, indeed, white workmen could not stand the hot, moist climate of the cotton-fields. The cotton-mills grew up in the Northern manufacturing States. The Northern manufacturer needed a tariff on imported goods to protect him from European competition; the Southern cotton-planter who purchased much of his supplies abroad was hurt by the tariff. After about sixty years of strained relations between the two sections there occurred the Civil War which wiped out nearly one million lives, and rolled up a debt, direct and indirect, of nearly six billions of dollars. The world's cotton-crop aggregates from twelve million to fifteen million bales yearly, of which the United States produces, as a rule, a little more than three-fourths. Egypt is rapidly taking an important place among cotton-producing countries, and, with the completion of the various irrigating canals, will very soon rank next to the United States. India ranks about third; China and Korea produce about the same quantity. There are a few cotton-cloth mills in these states, but in Japan the manufacture is increasing, the mills being equipped with the best of modern machinery. Brazil has a small product, and Russia in Asia needs transportation facilities only to increase largely its growing output. [Illustration: COTTON] The cotton-crop of the United States is quite evenly distributed; one-third is manufactured at home; one-third is purchased by Great Britain; and the remaining third goes mainly to western Europe. In the past few years China has become a constantly increasing purchaser of American cotton. New Orleans, Galveston, Savannah, and New York are the chief ports of shipment. The imported Egyptian and Peruvian cotton is landed mainly at New York. Most of the cotton manufacture is carried on in the New England States, but there is a very rapid extension of cotton manufacture in the South. =Wool.=--The wool of commerce is a term applied to the fleece of the common sheep, to that of certain species of goat, and to that of the camel and its kind. There is no hard-and-fast distinction between hair and wool,[32] but, in general, wool fibres have rough edges, much resembling overlapping scales which interlock with one another; hair, as a rule, has a hard, smooth surface. If a mass of loose wool be spread out and beaten, or if it be pressed between rollers, the fibres interlock so closely that there results a thick, strong cloth which has been made without either spinning or weaving.