Woolsack
The Cyclopedic Law Dictionary · Walter A. Shumaker and George Foster Longsdorf; ed. James C. Cahill · 1922
The Cyclopedic Law Dictionary
The seat of the lord -chancellor of England in the house of lords, being a large square bag of wool, without back or arms, covered with red cloth.
Webster.
The judges, king's counsel-at-law, and masters in chancery sit also on woolsacks.,The custom arose from wool being a staple of Great Britain from early times. Enc. Am.