Artificial glass horizon, circular anodized brass plate on three levelling feet with ivory knobs, covered with blackened glass plate (mirror), and with spirit level, signed and made by Francis Watkins and William Hill of London, c. 1850

Artificial glass horizon, rectangular anodized brass case on three levelling feet, covered with blackened glass plate (mirror), and with two spirit levels, in wooden case, signed and made by Elliott Brothers of London. c. 1880

Artificial glass horizon, rectangular anodized brass case on three levelling feet, covered with damaged blackened glass plate (mirror), with separate spirit level, in fitted wooden box, signed and made by Thomas Jones of London, 1811 - 1814

Artificial glass horizon, rectangular anodized brass case on three levelling feet, covered with blackened glass plate (mirror), with two spirit levels, signed and made by Elliott Brothers of London, c. 1860

Artificial glass horizon, circular anodized brass plate on three levelling feet with ivory knobs, covered with a blackened glass plate (mirror), with spirit level, in fitted wooden box, as used on the Antarctic Expedition of 1901, signed and made by Watkins and Hill of London, c. 1850

Artificial glass horizon, black glass plate on rectangular anodized brass case, in fitted wooden box with two detached spirit levels, signed and made by William Cary of London, c. 1860