Wiltshire Heritage Museum’s Book of the Month - http://www.wiltshireheritage.org.uk/library/ is -

Diary of a Dean

Being an account of the
EXAMINATION OF SILBURY HILL
and of
VARIOUS BARROWS AND OTHER EARTHWORKS ON THE DOWNS OF NORTH WILTS

Opened and Investigated in the Months of July & August 1849

By Dean John Merewether

With illustrations

An online edition of the book is here - http://books.google.co.uk/books?id=ILcHAAAAQAAJ&dq=silbury%20hill%20merewether&pg=PA3&output=embed