<p>Three rats using an orienteering compass, to determine the declination of a wall in preparation to designing a vertical declining sundial. The orientating lines are set along the needle, and the declination can be seen under the white line.
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The rat is measuring along the wall. The compass reads 302 degrees - add on 90 resulting in 392 degrees or 32 degrees from due south.
Clem Rutter, Rochester, Kent
CC BY 3.0
<span class="int-own-work" lang="en">Own work</span>