Plus or Minus One Ear

Letters

Vol. 34 No. 18 · 27 September 2012

From Emma Tristram

In his list of not-yet-standardised measuring systems, Steven Shapin could have added the phenomenon of ‘vanity sizing’, whereby the actual sizes of garments have increased over time relative to their nominal size (LRB, 30 August). This practice entails lying about the measurements used, in order (presumably) to sell more clothes to people who want to imagine themselves thinner than they might be. It’s very annoying.

Emma Tristram
Arundel, West Sussex

Vol. 34 No. 20 · 25 October 2012

From Ollie Brock

Steven Shapin skips quickly past what ought to be a cornerstone of his subject, the international prototype for the kilogramme (LRB, 30 August). It is a relic of a previous metrological era, being the sole surviving measurement derived from a manmade object. Seated in a laboratory just outside Paris and known to its carers as ‘le Grand K’, it was described by Mary Bowers in India’s Caravan magazine as being ‘hardly bigger than an apricot’.

Most of the experts Bowers consulted were optimistic at the time that the quadrennial conference of the Bureau International des Poids et Mesures (BIPM), held in 2011, would adopt a physical constant to replace the ageing prototype. In the end, the conference postponed the decision to its next meeting. Robert Crease, whose book Shapin is reviewing, says that the problem is weight loss ‘due to the escape of bubbles’ trapped in the metal. But Bowers quotes Richard Davis, the physicist in charge of the model, saying that the sister prototypes against which ‘le Grand K’ is measured could instead be getting heavier. Even if the kilogramme is losing mass, he told her, ‘there aren’t any serious theories’ as to the reason, only ‘possibilities’ – the evolving-out of hydrogen bubbles being one of them. ‘Others blame the cleaning process,’ Bowers wrote, ‘which has not been changed in over a century and still involves wiping the object manually with alcohol and a soft cloth.’

Ollie Brock
London E8