I am doing a project that involves pouring new concrete footings for several steel columns in my basement. I want as good a bearing surface between the concrete and the column base plate that I can get, which is why I am trying to think through how I will get the footing surface as level as I can get it. The thing that I never had to consider before is that every spirit level out there, from cheap to high end, all have a gap between the edge of the bubble and the lines on the vial. When using it you need to estimate how centered the bubble is. Does anyone know why levels are not made where the lines are spaced so that the bubble touches each one when the tool is level? That would seem to improve accuracy a great deal. Also, does anyone know of a trick to make precision leveling easier with a spirit level? Thanks.