Technology by the Metre

This traditional folding wooden ruler is printed on both sides with 200 years of human technological achievement. On one side there is an accurate mm and cm scale along with a timeline of events - at a centimetre per year!  The other side has a matching timeline of concepts and periods, labelled in colour, so you can flip the ruler to see different information. 

Folding wooden ruler, 2 metres long,
Printed on both sides,
Graduated in centimetres and millimetres.