To Triangulation

This is the day I've been scared and excited for since I landed on the island six weeks ago: Today we start to sink the center piles. I'll be directing traffic with two instruments. If the I-beams are in the wrong place in the river (I have an allowable error of 1/2") it's all my fault.

I've figured out how I'm going to position the beams, but I'm still unsure of how to check my work. It's a most necessary step.

I'll be going at it for the next two weeks so if anyone reads this, please wish me luck.