A _brochure_ of fifty pages, full of figures and tables, just issued, contains the criminal statistics of the metropolis, as shown by the police returns. It is not very pleasant reading, in any sense, but it no doubt has its value. We learn from it that last year the police took into custody 64,281 persons, of whom 29,863 were discharged by the magistrates, 31,565 summarily disposed of, and 2,853 committed for trial; of the latter number 2,312 were convicted, the rest being either acquitted or not prosecuted, or in their cases true bills were not found. About twenty years ago, in 1839, the number taken into custody rather exceeded that of last year, being 65,965; although since that period 135 parishes, hamlets, and liberties, with, in 1850, a population of 267,267, have been added to the metropolitan district, and although the entire population must have greatly increased in the interval. These returns exhibits strange variations in the activity of the police; while last year the apprehensions were, as stated, 64,281, in 1857 they amounted to as much as 79,364. The difference is 15,000, and of that number in excess, not one-half were convicted, either summarily or after trial, the rest forming an excess in the whole of those discharged by the magistrates. It is a striking fact that nearly half the number of all whom the police take into custody are discharged, so that the discrimination of the police is far from being on a par with its activity. Criminal London spends some considerable part of its time at Newgate, Clerkenwell, Wandsworth, Hollowway, and other establishments well-known to fame, and descriptions of which are familiar to the reader, but a favourite resort, also, is Portland Goal, which, by the kindness of Captain Clay, we were permitted, recently, to inspect. Portland Goal is situated on a neck of land near Weymouth.