Under the conditions considered inevitable with such teaching, although great wealth accompanied the rapid industrial development after the Napoleonic wars, it was associated with unrelieved misery; for homeworkers and rural workers crowded into mean hovels in towns, paying exorbitant rents out of a miserable pittance of wages, and were exposed to the evils resulting from overcrowding, and from absence of adequate and satisfactory water supply, scavenging or drainage. By the year 1851 about half the population of England and Wales had become aggregated in towns; and it may be added that in 1911, less than one fourth of the population was left in rural districts. Urbanization in the earlier years meant dense overcrowding and insanitation; and that it is still an influence adverse to health may be gathered from the information given by the census of 1911, that over eight times as large a proportion of the urban as of the rural population live in one-roomed tenements, and nearly twice as large a proportion live in two-roomed tenements, while the proportion of one-roomed tenements in towns which are overcrowded (in the sense of having more than two persons to a room) in towns is seven times as great, and of two-roomed tenements is twice as great as in country districts. Domestic misery was associated with commensurate industrial misery; overwork, in insanitary factories and workshops, regardless of the health of the “hands,” was the rule. The displacement between 1760 and 1800 of domestic by factory manufacture represented a new phenomenon in the world’s history, a true industrial revolution. It was the parting of the ages; destined not only to change the life of the people of England from preponderantly outdoor to preponderantly indoor; and to bring for them for many years all the disadvantages of unregulated town life; but also, owing to the rapid development of better roads, of canals, and then of railroads and steamships to end forever the practical segregation in which countries, and even neighbouring communities, had previously lived. It cannot be wondered at that under these circumstances the general death-rate was excessive, and epidemic disease spread with a rapidity and to an extent previously unknown.