Large section of George Darwin's tidal abacus
Large section of George Darwin's tidal abacus, 1892 (Inv.1925-947)
George Darwin's tidal abacus, 1892, see also 1925-948 and 1925-949
Large section of George Darwin's tidal abacus, 1892 (Inv.1925-947)
Section of 9 rods from George Darwin's tidal abacus, 1892