To us now, however, these reports are of the greatest value, being in many respects the most valuable official records existing on the subject. We learn from them, better than we do from any other source, as regards the various parishes of London, the nature, and in some measure the extent of the evils which existed, and the causes of those evils; we find in them opinions expressed and reiterated as to the best way of remedying those evils, and accounts of the results of the efforts made to remove or cure those evils. The reports set forth facts demonstrating the appalling misery which the great masses of the people of the metropolis endured; the loathsome foulness in which vast numbers of them habitually lived, and were allowed to live; the dreadful hardships they had to suffer; the fearful moral and physical contamination they underwent; the terrible death-roll--in great part preventable--and the ten or twenty-fold larger roll of victims of preventable illnesses and epidemics, with the consequent poverty which sickness entailed. We can bit by bit piece together from these reports a realistic picture of the sanitary condition of London as a whole during the successive periods of the latter half of the nineteenth century, and we can discern the action of the silent, steady, and irresistible economic forces which unintermittently dominated that condition. North and south in the metropolis, east and west, it was all the same, varying only in intensity, in extent, and, in some degree, in form; a harrowing and almost incredible story. And the remarkable concurrence of testimony from men acting independently of each other, and resident in wholly different parts of London, justifies the fullest confidence in statements uniformly harmonious. The metropolis is so large a place, with such marked differences between its component parts, differences in situation, and physical characteristics, and degree of development--differences in wealth and poverty, and in the occupations of their inhabitants--that the attempt to trace any special branch of its history is beset with the greatest difficulties. Especially is this the case when the subject treated of is so complex and comprehensive as that of the public health. It is manifest that all parts of the metropolis cannot be described simultaneously--whilst to go "seriatim" into the history of the public health in each separate locality would, by the very weight of detail, fail to convey an impression of the subject as a whole. The same objections apply to a "seriatim" historic treatment of the different branches of the public health. Moreover, the action of the central authority has also to be described in its proper place. And, still more important, the action of Parliament, and the principal Acts of Parliament relating to matters affecting the public health, either directly or administratively.