Circular slide rule, c 1870.

Circular slide rule, c 1870.
A circular engineer's slide rule made by Apps, c.1870. A circular slide rule affords a long and therefore accurate logarithmic line in a small amount of space. The potential of circular rules was not really utilized until the Victorian period, when several spiral and helical designs appeared on the market.
 
Currently on display in:
Mathematics
Year made :
1870-1875
Inventory number :
1911-199