From Terry Quinn
Readers of your brief report on the watt balance made from Lego (20/27 December 2014, p 14) might be interested to see the video of the original Lego balance I made last year with my then 11-year-old grandson Lucas and a colleague, Richard Davis ().
We showed it at the Royal Society Summer Science exhibition in London in 2013 and published an account in Physics Education (). Lucas constructed the Lego part on his dining room table, I made the rest in my basement and Richard honed the intellectual firepower of the three of us.
Our version inspired the much-improved Lego balance that you describe, built by the US National Institute of Standards and Technology.
Sèvres, France
