The picture above shows the two sides of this boxwood slide rule. It is dated to c1840 as which is presumably to be made by S. Cock. According to Directory of British Scientific Instrument Makers 1550-1851, p. 60, S. Cock was known to be making gauging instruments at around 1840, and his store office was located at Broad Street, London.
A similar slide rule and a brief history of which can be found in this page.
