Pentland Firth is the strait between the Orkneys and the Scottish mainland connecting the North Sea with the Atlantic, 12 m. long by 6 broad, and swept by a rapid current very dangerous to navigation; 5000 vessels traverse it annually.
Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)
Penthièvre, Duc de * Pentonville