Trust the Instrument

I should not have been back here today.

Review of yesterday's data presented an absurdity. Acording to my log a culvert (typically an under road surface water drain) was higher at the end where it discharged than where water entered it up stream. I examined the structure quite closely while on site, noting that it was clogged up with quite a lot of autumn debris and had an odd looking repair done at some stage. Surely I would have noticed this anomoly?

If not absolutely convinced an error had crept in I was certainly not comfortable publishing the results to the client. There followed an unplanned (and unbudgeted) revisit to the site. 

Measurements repeated; sure enough the data logged originally was indeed correct. With hindsight, a  wasted visit, but at least I wont lie awake thinking about it now.