Radius of the Earth Measurements

 

“Transcontinental Triangulation and the American Arc of the Parallel”

Ocean to ocean survey. Shows triangulation with spherical excess.

ftp://ftp.library.noaa.gov/docs.lib/htdocs/rescue/cgs_specpubs/QB275U35no41900.pdf

Page 221 for Spherical Excess

Overview of several different measurements circa 1906:

History of the Determination of the Figure of the Earth from Arc Measurements