Celsius scale solid-stem, mercury-in-glass thermometers for electrically or clockwork driven aspirated hygrometers more accurate than the whirling hygrometers described in BS 2842. Essential details of remainder of instrument. Guidance on methods of use and errors in computed humidity.Cross References:BS 800BS 2011:Part 2.1DbBS 2842BS 3456:Part 101BS 5750International Temperature Scale of 1990