As a matter of fact, the powers of making additions to the Metropolitan District, acquired in 1839,[216] were only taken advantage of to a very small extent, and the growth of the Metropolitan Police was almost entirely confined within the limits originally assigned to it. In 1840 the Houses of Parliament and the London Docks were taken over; next came the Woolwich and Deptford Yards; Woolwich Arsenal, and Greenwich were incorporated in 1843; then the Tower of London, and finally the Royal Dockyards (Portsmouth, Devonport, Chatham, and Pembroke Dock) were policed by the Metropolitan force in 1860. The entire establishment, which in June 1830 was 3314 of all ranks, had risen to 5625 in 1852, and ten years afterwards a new division (X) was created to deal with the crowds which were expected to visit the second International Exhibition. In 1864 the total strength was 7113. Colonel Rowan resigned in 1850, and in 1856 the two Commissioners were replaced by one Commissioner (Sir R. Mayne) and two Assistant Commissioners. At first no steps were taken to fill the gap caused by the disappearance of the Bow Street Runner, and the Popay incident discouraged the Commissioners from venturing on what was felt to be dangerous ground. The lack of a detective service was a great source of weakness, and so in 1842 a new department, especially devoted to this very necessary branch of police work, was instituted by Sir James Graham, and attached to Scotland Yard. A small staff was selected out of the uniform branch to form a nucleus. At first the department only consisted of three inspectors and nine sergeants; soon afterwards six constables were added, and gradually the numbers were increased until in 1878 the whole detective service was reorganized, and the Criminal Investigation Department created. At the time when the Metropolitan force was the only efficient police in the kingdom, individual officers, it may be remembered, were often sent to the provinces, on loan or permanently, to assist in the formation of similar organizations in other parts of England; this of course was right and proper, and was attended by the best results. Subsequently, the practice arose of temporarily drafting large bodies of London policemen to keep the peace in distant districts wherever disturbances were feared, a course of action sound enough in theory perhaps, but seldom found effectual when put to the test of experience. An English mob quickly resents high-handed interference, and will not tolerate at the hands of strangers the same degree of repression it would quietly submit to from local peace officers.