3 ms·
Height contours of topographic maps have existed more than 100 years.
by hasa 8y ago
Height contours of topographic maps have existed more than 100 years.
- arethuza 8y agoActually, almost 250 years: https://en.wikipedia.org/wiki/Schiehallion_experiment https://en.wikipedia.org/wiki/Schiehallion_experiment