Slide rule for calculation of treadwheel labour
1823
1823
1800
mid-1800s
1824
1830
1815-1825
1824
1808-1828
1825
1810-1820
1825-1835
1824
1808-1815
1823
1830-1900
1823
1801-1830
1808-1847
1824
1824
1824
circa 1820
1801-1830
1824
1824
1824
1826-1830
1824
1826-1830
1824
1824
1850-1900
1840-1845
1824
1824
1824
1824
1808-1828
1826-1830
1830
1830