BARREL-OF-BUTTER, an islet, in the parish of Orphir, county of Orkney. It is one of the smallest of the Orkneys, and is situated to the south of the island of Pomona, in Scalpa Flow, a large expanse of water resembling a small Mediterranean Sea. Here was formerly a seal-fishery, for which the neighbouring farmer paid the proprietor a barrel of oil yearly, until the frequency of shipping scared the seals from the isle, when the proprietor, determined not to lose his rent, converted the tack-duty into a barrel of butter, which is still paid by the tenant. Hence the isle derives its present name, the ancient one being Carlin-Skerry.
Transcribed from A Topographical Dictionary of Scotland, 1851 by Samuel Lewis