Valentine Artist Boyd Elder Sets a Contour January 9, 2010 Chris Gill All patterns are plowed on contours which are reset every 200 feet. The device shown here is an optical transit. We now use a laser transit which can be operated by one person and which is much faster. Share on Facebook Share on Twitter Share on LinkedIn Previous Next Author: Chris Gill Ranching, wildlife management, finance, oil & gas, real estate development and management.