Thursday 14 October 2010

The bolometer

The thermal people often refer to bolometers. These basically are remote thermometers, and usually work by focussing heat radiation onto something which changes its characteristics, in a measurable way, when it warms up. The original version used a platinum foil strip blackened with soot from a candle. Its electrical resistance changed with temperature. The inventor was Samuel Pierpont Langley, in 1878.

This gave rise to the following rhyme/limerick which was quoted several times during the Infrared 100 events last week.
Oh Langley devised the bolometer
Which is really a kind of thermometer
Which can measure the heat
From a polar bear's feet
At a distance of half a kilometre
Who said science can't be fun! Sadly, it seems Langley actually measured the temperature of a cow from a quarter of a mile ... but that doesn't rhyme [Ref]. There are variations and I believe the original rhyme is by Mr Anon.