Add 'next' links to various chapters of survey guide pages

handbook/survey/gps.htm

@@ -57,6 +57,7 @@ too.</b></p>
 on coordinate systems</a> has been moved to a different page. If you are really interested you can read 
 <a href="coord.htm">Olaf's article</a>too.
 
-
-<hr /></body>
+<hr />
+<a href="newcave.htm">Next survey guide page - 'Base Camp: getting it in to the computer'</a>
+</body>
 </html>