Pentonville Prison, 1870.

ENGLAND - JUNE 14: A photograph of inmates of Pentonville Prison, London, employed in construction work, taken by Captain Lewis, probably of the Royal Engineers, in 1870. Wearing prison uniform with the traditional arrow markings, these men are harnessed to a wheel for grinding or crushing rocks. A guard looks on in the background. Pentonville Prison was designed by Sir Joshua Jebb (1793-1863) and completed in 1842. It was a model prison built according to Jeremy Bentham's (1748-1832) concept of the 'Panopticon', consisting of five blocks radiating from a central point. (Photo by SSPL/Getty Images)