Clarke's Hydrometer (c. 1755)
1755
1755
1850-1860
1885-1936
1875-1900
1830
1873
1816-1873
1780-1790
1920-1930
1801-1820
1810-1830
1930
circa 1823
1870-1940
1830-1900
1781
1940-1950
1961
1840
late 19th century
1870-1930
1740-1800
1894-1930
1896
1903-1938
1920- 1960
1871-1900
1940-1860
1825-1835
1815-1825
1870-1930
1940-1950