In telecommunication, effective Earth radius is the radius of a hypothetical Earth for which the distance to the radio horizon, assuming rectilinear propagation, is the same as that for the actual Earth with an assumed uniform vertical gradient of atmospheric refractive index.
Note: For the standard atmosphere, the effective Earth radius is 4/3 that of the actual Earth radius.
... as 1447, which still remains in manuscript.
The first printed French copies appeared at
Toulouse 1488. The earliest German translation was
made in 1434 by J. de ...