
The SciencesJune 21, 1919
Surveying and Mapping from Airplanes
How Recent Experience in War Mapping May Be Applied in Completing Our Topographic Map

Surveying and Mapping from Airplanes
How Recent Experience in War Mapping May Be Applied in Completing Our Topographic Map

The use of Mean Sea-Level as the Datum for Elevations
An Engineering Problem of National Importance