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.