xyster wrote:Use the water bottle technique somebody else posted. Partially fill a clear 2 liter; set it down on the road lengthwise; take a pic from ground level; post the pic.
This is lousy sampling technique. Ya can't say how representative that 8-10" patch of road (that the bottle is resting on) is versus the overall...
Try a 4' piece of clear plastic tube with water in it. Fasten to a 3' piece of wood so tube "loops" and the water level at each end is level w/the wood. Wood is then absolutely level. Add another wood piece bolted at one end (so opposite end can be raised/lowered) level with the water, and standing at the bottom of the hill, sight along this piece and move it down `til it lines up with the hilltop. Measure how far this piece is lower than the water level at the opposite end of the tube (from the bolted end.)
Hard to describe, but hopefully you get the idea. Calc the slope from the ratio of 3' to the inches the "sighting" piece is below the water level at the opposite end of the tube from the bolt end.
You could do something similar w/a plumb bob and dispense w/the fluid.
Or, like Ypedal said, borrow a GPS