trades not classed as manufactures.  It is safe to assume, then, that one-third of the whole population is supported, directly, or indirectly, by manufacturing industry.”  Taking, however, the number of persons directly supported by manufactures, namely about six millions, reveals the astounding fact that the white laboring population, divorced from the soil, already exceeded the number of slaves on Southern farms and plantations.

Immigration.—­The more carefully the rapid growth of the industrial population is examined, the more surprising is the fact that such an immense body of free laborers could be found, particularly when it is recalled to what desperate straits the colonial leaders were put in securing immigrants,—­slavery, indentured servitude, and kidnapping being the fruits of their necessities.  The answer to the enigma is to be found partly in European conditions and partly in the cheapness of transportation after the opening of the era of steam navigation.  Shrewd observers of the course of events had long foreseen that a flood of cheap labor was bound to come when the way was made easy.  Some, among them Chief Justice Ellsworth, went so far as to prophesy that white labor would in time be so abundant that slavery would disappear as the more costly of the two labor systems.  The processes of nature were aided by the policies of government in England and Germany.

The Coming of the Irish.—­The opposition of the Irish people to the English government, ever furious and irrepressible, was increased in the mid forties by an almost total failure of the potato crop, the main support of the peasants.  Catholic in religion, they had been compelled to support a Protestant church.  Tillers of the soil by necessity, they were forced to pay enormous tributes to absentee landlords in England whose claim to their estates rested upon the title of conquest and confiscation.  Intensely loyal to their race, the Irish were subjected in all things to the Parliament at London, in which their small minority of representatives had little influence save in holding a balance of power between the two contending English parties.  To the constant political irritation, the potato famine added physical distress beyond description.  In cottages and fields and along the highways the victims of starvation lay dead by the hundreds, the relief which charity afforded only bringing misery more sharply to the foreground.  Those who were fortunate enough to secure passage money sought escape to America.  In 1844 the total immigration into the United States was less than eighty thousand; in 1850 it had risen by leaps and bounds to more than three hundred thousand.  Between 1820 and 1860 the immigrants from the United Kingdom numbered 2,750,000, of whom more than one-half were Irish.  It has been said with a touch of exaggeration that the American canals and railways of those days were built by the labor of Irishmen.