WCC77948:
The movement of H.4, a longitude timekeeper designed and drawn by John Harrison, c.1760-72 (ink on paper), Harrison, John (1693-1776) / Bridgeman Images
WCC106112:
Drawing of the layout of the movement of the H4 timekeeper by John Harrison (1693-1776), c.1759 (pen and ink on paper), Harrison, John (1693-1776) / Bridgeman Images
WCC106104:
Gridiron pendulum designed for the construction of precision long case clocks, 1726 (drawing), Harrison, John (1693-1776) / Bridgeman Images