deletions | additions       diff --git a/Gaussian Coordinates.tex b/Gaussian Coordinates.tex  index 3cea475..54c53d8 100644  --- a/Gaussian Coordinates.tex  +++ b/Gaussian Coordinates.tex 
...
\section{Gaussian Coordinates}  Two neighbouring points $P$ and $P'$ on the surface then correspond to the co-ordinates  where $du$ and $dv$ signify very small numbers. In a similar manner we may indicate the distance (line-interval) between $P$ and $P'$, as measured with a little rod, by means of the very small number ds. Then according to Gauss we have. Under these conditions, the $u$-curves and $v$-curves are straight lines in the sense of Euclidean geometry, and they are perpendicular to each other. Here the Gaussian co-ordinates are simply Cartesian ones.