diff --git a/handbook/survey/coord.htm b/handbook/survey/coord.htm
index 767f766be..ee5a4ce20 100644
--- a/handbook/survey/coord.htm
+++ b/handbook/survey/coord.htm
@@ -112,6 +112,8 @@ typically result in coordinates that are around 500m off, which is unacceptable
 for locating a cave entrance on the plateau. So we can't just ignore the
 ellipsoids but have to get their definitions right.
 </p>
+<a href='/handbook/survey/l/orthoheight.html'><img width=85% src='/handbook/survey/i/orthoheight.jpg' /></a>
+
 
 <h2>Geoids</h2>