Title: The greatest speed
Description: A high-school/undergraduate introduction to the history of measuring the velocity of light. Even for non-maths experts, it is very accessible, with lovely biographical details of many of the leading scientists. The translation (from Russian) is sometimes quirky, but this is easily overlooked. The line diagrams are generally useful. There is no equivalent book anywhere I have seen, so it's a pity it's out of print. My copy is too precious to sell!
Subjects: History, Light, Measurement, Speed