Plate, 'Sections through Arthur's Seat' by unknown artist Drawings of three sections through Arthur's Seat in Edinburgh, Scotland demonstrating specific gravity. Different colours indicate the locations of sandstone and trap rock in the formation. Subject: Geodesy Published in Philosophical Transactions as 'On the deflection of the plumb-line at Arthur's Seat, and the mean specific gravity of the earth'. Received by the Royal Society on 11 February 1856. Read 21 February 1856. [1856]