Most of our kit has to be reasonably weatherproof. Electronics and water are not the best mix so some of the survey machines require more pampering than others. The total station is ok in a bit of rain but can be a bit of a drama queen about a continuous soaking. This leads to repeated showings of one particular error message – 051 weak signal error – which I take to really mean – my works are full of condensation, should we not go down to the shed and have a cup of tea and a fag.
It has become almost a tradition (i.e. it’s happened twice) that I get to steal whoever is the student intern on the Ribchester project for a day to help us with our pre-excavation survey. This year it was Ashley’s turn to have a day off from reading through reports on 20 year old excavations and come and hold a survey staff in the rain instead.
Ashley is the blue dot just visible through the rain in this photo I took as we were setting up the total station. This morning’s job was to use the survey equipment to accurately place the trenches on top of the archaeology we detected last year. I calculated the national grid co-ordinates of the three trenches yesterday.
Once the machine has been set up (see last year’s post from the same stage of the process), then there is a nifty application in the software that allows you to guide your surveyor’s mate backwards and forwards across the field until you have pinned down the co-ordinate you were looking for. We have marked the corners of trench M (on the left) and N (on the right) here with wooden stakes. Back in the nice dry office I have then drawn the outlines on in Photoshop for added clarity.
This is a closer view of M, Photoshopped as before. This one is over a pit or large posthole, one of a group of two together in the gradiometer results.
Slightly to the south-west is the much larger pit where we have put trench N. This may also be prehistoric but it is very close to the large double bank and ditch which we think is the boundary of the medieval deer park.
We also have a trench across this feature, which is going to be trench P. Here we are looking east at where the trench is going to be and back along the line of the boundary.
Now we just have to spread the dismantled bits of total station out on the dining room floor to dry so that it will work for the rest of the dig.