Arthur Buchanan of Sound can be seen from the arms as a closer relative to Buchanan of the Ilk. The arms being differenced by the inclusion of a crescent in dexter chief. The crescent is the sign of a second son, and when can therefore perphaps assume that he he was second son, or descended through a second son.
The name 'sound' is used in the Orkneys for channels of water, and the family of Buchanan of 'Sound is used in Orkneys for channels of water, and the family of Buchanan of 'Sound and Shapinshaw' is mentioned in Margaret Stuart's Scottish Familty History, in the proceedings of the society of Antiguaries (189) 277 James, the third son of Robert Buchnan of Leny was called James of Shirrahall, Orkney, but would have been living at an earlier period than Arthur Buchanan Sir John Buchanan of Scotscraig, second son of Robert Buchanan of Leny Purchased the lands of Sound and Shapinshaw from James Tullo. Sir John was dead in 1642, and his son in-law Harry Erskine sold the properties to Thomas Buchanan sherrif of Orkney.
Thomas Buchanan was provost of Kirkwall in the Orkneys between 1636 - 1647, and left the property of Sound amongst other properties to his eldest son Arthur. James Buchanan, above, was brother to Sir John of Scotscraig and father of Thomas.
Details regarding the family can be found in 'Xirkwall in Orkneys'.