Portable Sikes' hydrometer by Dring and Fage
1873
1873
1870-1930
1802
1860
1830-1860
1927
1941
1901-1910
1816
1900-1970
1820-1855
1930-1970
1900-1910
1816-1873
1940-1950
1903-1938
1815-1825
1930-1970
1957
1850-1870
1901-1910
1867
1840-1940
1850-1930
1850-1900
1830
circa 1823
1900-1950
1910
1870-1930
1830
1930
1896
1900-1950
1860-1870
1830
1900-1950