It was a beautiful morning in Caithness, cold and clear, but as it happened the only cloud in the sky at dawn veiled the sun!
Camster Round shortly after dawn, and after the sun had emerged from behind cloud. The nearby long cairn of Camster Long can be seen beyond (Photo: Aaron Watson)
Still, there was sufficient light to see what would happen inside Camster Round if the sky had been clear. For a brief time the sun illuminates the floor of the passageway and even reaches the stone at the very rear of the chamber. It was evident that an image of the sun would be projected inside the monument, similar to observations at Bryn Celli Ddu.
Looking out along the passage, showing how sunlight illuminates the floor (Photo: Aaron Watson)
Direct sunlight reaching to the very rear of Camster Round's chamber at dawn (Photo: Aaron Watson)
We did not put an aperture screen in place to attempt optical projections. Instead, we were able to note how the configuration of Camster Round's passageway obstructed the movement of light such that the monument acts as a camera obscura without further modification. The resulting projections in the chamber were not nearly as well defined as those produced by a smaller aperture, but they had sufficient presence for us to see that human figures appeared upside down.
I find this interesting as it offers a means by which Neolithic might have become aware of optical projections, irrespective of whether they were intentional in the design of Camster Round's architecture.
A full account will be posted in the archaeo-optics pages in due course.