Harmonograph, 1909.

Fleming's original thermionic valve, 1889.

S C Tisley's compound pendulum, 1876.

Spring-driven watch with cylinder escapement, 1701-1800.

Pair of early Bell telephones, 1878.

Fruit-powered clock, 1998.

Amici microscope, 1841.

Model of a magnesium atom according to the

Harrison's second marine chronometer, 1737.

Plan of the Principal Triangulation of Britain, 1787-1790.

Designs for the Bell Rock Lighthouse, c 1800.

'Imposible staircase', 1950s.