Surveying with RCAHMS at Law of Dumbuils

This week I have been following in Yvonne’s footsteps and learning about plane table drawing from the RCAHMS surveyors, Ian, George, and John at Law of Dumbuils hillfort.

When we first visited the site, George suggested I spend half an hour making a quick sketch of how the structure of the fort appeared to me. It was a little overwhelming at first as the fort is made up of multiple ramparts and full of lumps and bumps.

At first it was difficult to disentangle all of the features at Law of Dumbuils

The Wild (“Veelt”) RK1 alidade is the workhorse of RCAHMS surveys – no longer made and older than George!

When surveying, RCAHMS use a mix of traditional and hi-tech methods, from plane-table surveying to differential GPS surveying. This gives them a full and balanced understanding of a site. The primary tool used is a self-reducing alidade, typically with a 1:500 scale. Ian, a draughtsman with 40 years experience, explained that this scale removes a degree of subjectivity and any small errors that may occur when recording.  After Ian had explained to me how the alidade works, I started to record some of the fort’s features with the help of John. By the end of the day the plan was starting to take shape!

Familiarising myself with the alidade.