leighandgill

Archaeology in East Oxford

Building Survey

On Friday and Saturday, there was a building survey at Bartlemas Chapel; Gill and I were booked in on the Friday session. This was to give us an introduction to the gentle art of doing a scaled drawing of the elevation of a building, in this case our old friend, Bartlemas Chapel. We met up with Jo a bit early at ArkT to pick up the gear we needed and then headed off to the Chapel. I was really gratified to see that there was virtually no trace of all our fevered activity just under a year ago.

A year (almost) after there was a large trench here, and now hardly a sign of all our hard work.

So, after the usual signing in, health and safety and introductions, Jo and Jane started to explain how we were going to go about doing the drawing. In a lot of ways it’s just like drawing a section of the side of a trench – only you’re looking up instead of down! Just like doing a section the first thing is to measure the length and depth (or height in our case) of the area which we’ll be drawing, and then work out what scale (1:10 or 1:20, say) we are going to use given the size of paper we have. A fair amount of head-scratching ensued, but there is nothing so irritating as drawing away merrily for hours, then dropping off the edge of the drawing board – a bit of time spent in preparation is very well spent. Then start by putting in the title (where we are and what we are drawing) the date, the scale and who was doing the drawing. Preparation of the paper done we then started on the wall itself.

This is where it diverges from doing a section – one can’t start hammering nails into a grade 1 listed building! The principal is the same, though; we need a datum, a reference from which all the measurements can be taken. So the first thing to do was set up the dumpy (no one can remember why it’s called that – everyone remembers being told, but as no-one remembers it must be a pretty boring explanation).

Setting up the dumpy

After it has been levelled, with a built in spirit level, we started putting in the datum line; normally we use a string (we had brought some road pins along to stretch the string between, but found we couldn’t push them into the ground) but this time we used a chalk line drawn on the stone work – it will wash off in the first rain. So using the dumpy we drew a line at the same height all along the wall which we would be drawing. Then the fun started.

Basically, the procedure is that we measure a set of prominent points (the corners of distinctive stones, for instance), draw them in, and then freehand the intervening detail. Sounds simple, eh?

Two of us measuring a point on the buttress.

Just by Jo’s head you can see the datum line continuing along the wall from where she is holding the tape so Andrew can measure the vertical distance to the point which we are going to plot. We used the measuring staff, which is leaning up against the buttress, to do the points which were too high for the steel tape.

So after we’ve got a few points measured, then the drawing starts.

The hard work – doing the actual drawing.

This, of course, is the whole point of the exercise. We have had a laser scan done of the building, and have obviously taken a shed-load of photos, but there is no substitute for drawing – the human eye is capable of much better discrimination than any photo. It’s not so much a matter of  “accuracy”, but the ability of a combination of really looking at a subject, then using the drawing to bring out the relevant details.

So after a lot of hard work the end result looks something like this – this is one I prepared earlier ( to coin a phrase) – it’s the end, and the start of the other side, of the buttress that Jo & Andrew are measuring in the photo above.

The end result – the second group started quite a bit later than the first one.

Another group carried on on Saturday, and when Gill & I popped in on Saturday afternoon to have a chat, Jane said we might well carry on Sunday, as quite a few of us are going to be at the Chapel as part of Oxford’s “Open Doors” event. Christopher & Sarah Franks are opening the Chapel so the Project is going to lend a hand (they got a bit overwhelmed last year by the unexpected number of visitors) and do a bit of explaining about what we found during the dig last year. Hopefully there will be a bit more of the chapel to show in a later blog.

Leigh

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