The chemical film method which was reported by Walker (TINA 1949) is reexamined and improved with a 2.5m Hakubasan-maru (a Maier formed cargo boat) and a wall-side model. The laminar flow area as well as the separated area is clearly detected on both models. The method is further shown as applicable to stream-line measurements along models when a number of small protrudes are prepared, the diameter and height of which are carefully determined and varied referring to the flow characteristics of the boundary layer at each distance from the bow.