Preparing a SiteWoody stems are preferred, but this technique works on most herbaceousspecies.Expose a suitable area of water conducting xylem tissue or sap wood(approximately 3cm x 1cm) to ensure that the psychrometer chamber wellwill be completely covered by the sample. Remove the bark, phloem andcambium layers, using a single edged razor blade to scrape a flat area ofxylem upon which to mount the psychrometer. Be very careful to maintain alevel plain to prevent producing a concave or convex surface.Ensure that the surface is flat and there are no small gaps between thepsychrometer chamber and the xylem surface.Thoroughly clean the area with distilled water and wipe dry. It is important tothe success of the installation that all living tissue is removed and no freewater is left on the xylem surface.