"It is the practice of carpenters herabouts, when laying out and leveling up the foundations of relatively long buildings, to use a garden hose filled with water, with glass tubes 10 to 12 inches long thrust into the ends of the hose. The theory is that water, seeking a common level, will be the same height in both the tubes and thus effect a level. Now the question rises as to what happens if a bubble of air is left in the hose?" Would important inaccuracies be caused? http://img100.imageshack.us/img100/9878/airbubble9bg.jpg [Broken] There should be a relatively simple approach to it, but I just can't seem to figure it out. Any help would be much appreciated.