The Criminal Investigation Department is under Mr. Basil Thompson, a comparatively young man who came from the Prison Commission to succeed Sir Melville Macnaghten, and who has successfully experimented with some new ideas to make the path of the criminal more difficult. Mr. Frank Elliott, who was formerly at the Home Office, holds sway over the Public Carriage Office; and the Hon. F. T. Bigham, a barrister--and a son of Lord Mersey, who gained his experience as a Chief Constable of the Criminal Investigation Department--deals with and investigates the innumerable complaints and enquiries that would occur even in a police force manned by archangels. Mr. Bigham is also the Central Authority under the terms of the international agreement for the suppression of the white slave traffic. There are six Chief Constables, mostly ex-military officers. One of these assists in the administration of the Criminal Investigation Department, the remainder control districts of four or five adjoining divisions. To adopt a military simile, they may be compared to major-generals in command of brigades, with each division representing a battalion, and the superintendents, colonels. Only once in the whole history of the Metropolitan Police has a man risen from the ranks to the post of Chief Constable, though many, like Mr. Gentle at Brighton, and Mr. Williams at Cardiff, have become the heads of important provincial forces. The post of superintendent in London is at least equivalent in its responsibilities to the average chief-constableship of the provinces. There are metropolitan section sergeants who have as many men under their control as some chief constables of small boroughs. The unit of the Metropolitan Police is a division which averages about a thousand men. Each is under a superintendent, with a chief-inspector as second in command. Thereafter the ranks run: UNIFORM BRANCH. DETECTIVE BRANCH. { Divisional Detective-Inspectors. Sub-divisional Inspectors { Central Detective-Inspectors. Inspectors Detective-Inspectors Station-Sergeants First Class Detective Sergeants. Section-Sergeants Second Class Detective-Sergeants Constables (reserve) Third Class Detective-Sergeants Constables (according to Detective-Patrols seniority)