TY - JOUR AU - John Hall BT - Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences DA - 10/2011 DO - 10.1098/rsta.2011.0239 PY - 2011 SP - 4090 EP - 4108 T2 - Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences TI - Learning from the time and length redefinitions, and the metre demotion VL - 369 ER -