E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
A seat made by two bearers with their hands. On Candlemas Day the children of Scotland used to bring their schoolmaster a present in money, and the boy who brought the largest sum was king for the nonce. When school was dismissed, the king was carried on a seat of hands in procession, and the seat was called the kings chair.