This is...

What scrambles my brain when I try to understand it:

I think I've got a strange one this week... I am a building designer and I work with levels on plans all the time. But I am stuffed if I can understand how surveyors take levels! My dad was a surveyor and he's tried to explain to me many times, as has my boss who did some surveying work as well. I just don't get it! How can a man with a pole figure out how high a spot is 50m away? Anyone who understands this is genius in my book!

Thanks to Flightless Boyds for this week's theme (it was good to have the choice of two).