Proportional dividers Royal Museums Greenwich

National Museum of American History

Tools at Jerry's Artarama

Horary quadrant with Gunter projection

Horary quadrant with Gunter projection

OMNIA - dividers

Proportional Dividers Smithsonian Institution

proportional dividers – Peachey Conservation

Greenwich near London': the Royal Observatory and its London networks in the seventeenth and eighteenth centuries, The British Journal for the History of Science

National Museum of American History