Harrison is of course best-known for his ground-breaking marine chronometer, the pioneer project to which Harrison devoted his life.
The compass was an earlier work made by Harrison in 1718 at the age of 25. The 360 degree dial was drawn in ink on manuscript paper and bore a 16-point wind rose with East and West transposed. It was signed and dated to the centre of the rose.
The piece has been published in Maurice J. Kenn's John Harrison's Unusual and Unique Magnetic Compass for the journal British Sundial Society Bulletin volume 14.
The signature and lettering on the dial were verified as genuine by Harrison expert Andrew King and the National Maritime Museum, who hold a similar plane-table compass made over 50 years earlier by Walter Hayes.
The piece had a cracked glass and some staining to the card but it is thought to be the first Harrison compass to appear on the market.
Lack of a precedent is always a disadvantage when it comes to setting estimates, but, given the Harrison associations, a £6000-8000 estimate sounded low key and so it proved. The bidding duly reached £45,000 with the hammer falling to a private collector bidding over the phone.
