[Vo]:Macedonio Melloni's 1846 Moonlight Experiment
The first person credited with detecting heat from moonlight was Macedonio Melloni in 1846. Below is a brief description of the experiment from "Infrared metaphysics: the elusive ontology of radiation. Part 1" by Hasok Chang , Sabina Leonelli. (Btw, I have read elsewhere that the experiment was performed on top of Mount Vesuvius rather than on his apartment balcony. Scientific folklore perhaps?) There is a link below of a video described as a reconstruction of Melloni's experiment. However it is only a laboratory demonstration using an electric burner as a source of infrared radiation, but it does use Melloni's large fresnel lens which is worth seeing. If the temperature change observed by Melloni was the same as in the video, then he observed an increase of only about 0.25 degrees. begin quote: <> end quote a reconstruction of a historical experiment https://youtu.be/iDcy21D6LLc Harry
Re: [Vo]:Macedonio Melloni's 1846 Moonlight Experiment
One wonders what Melloni's detector was. Very sensitive was Edison's tasimeter, which from what I've read could detect radiation from individual stars at the prime focus of a telescope. ‐‐‐ Original Message ‐‐‐ On Monday, January 17th, 2022 at 2:47 PM, H LV wrote: > The first person credited with detecting heat from moonlight was > > Macedonio Melloni in 1846. Below is a brief description of the > > experiment from "Infrared metaphysics: the elusive ontology of > > radiation. Part 1" by Hasok Chang , Sabina Leonelli. > > (Btw, I have read elsewhere that the experiment was performed on top > > of Mount Vesuvius rather than on his apartment balcony. Scientific > > folklore perhaps?) > > There is a link below of a video described as a reconstruction of > > Melloni's experiment. However it is only a laboratory demonstration > > using an electric burner as a source of infrared radiation, but it > > does use Melloni's large fresnel lens which is worth seeing. If the > > temperature change observed by Melloni was the same as in the video, > > then he observed an increase of only about 0.25 degrees. > > begin quote: > > < > a magnificent lens out to the balcony of his apartment in Naples. He > > had just received the lens, one meter in diameter and the finest he > > had acquired so far for the Osservatorio Metereologico then under his > > direction. Melloni expectantly trained the powerfully focused > > moonlight on his 'thermomultiplier', the most sensitive thermometer > > yet known to science. To his delight, the thermomultiplier needle > > swung immediately on receiving the light. Over the ages moonlight had > > been considered the archetype of 'cold light', famously listed under > > the heading of 'negative instances of heat' in Francis Bacon's > > analysis of thermal phenomena designed to illustrate the methods of > > the new inductive science in the seventeenth century. Marc-Auguste > > Pictet in the late eighteenth century focused moonbeams into a bright > > light, but still detected no heat. Now Melloni had finally shown the > > fallacy of the old opinion. Only moments later, however, Melloni's > > delight turned into puzzlement as he noticed that the direction of the > > needle-swing indicated a cooling of the thermometer by the moonlight. > > That would not do. Melloni considered possible sources of error, made > > calculations, and cajoled the instruments, repeating the trials until > > he managed to produce a repeatable detection of a positive heating > > effect. > > This was not a frivolous experiment. Melloni was at the height of a > > productive research career that earned him the epithet of 'the founder > > of the science' of radiant heat, even 'the Newton of heat'. He made > > the moonlight experiment with a very specific purpose in mind: Melloni > > needed moonlight to have heat, in order to uphold his recent > > conversion to the view that illumination and radiant heat were both > > effects of one and the same cause. The radiation of heat (unmediated, > > near instantaneous transfer of heat) had been the subject of active > > research at least since about 1790, but the nature of radiant heat had > > still not been elucidated thoroughly. Melloni's importance in the > > history of science now rests mostly on his contributions toward the > > identification of radiant heat as long-wavelength light, but curiously > > he had spent the 1830s piling up experiment after experiment that went > > against the idea that 'obscure radiant heat' was 'invisible light'. > > His experimental arguments had convinced many others to turn away from > > the apparently absurd notion of non-illuminating light.>> > > end quote > > a reconstruction of a historical experiment > > https://youtu.be/iDcy21D6LLc > > Harry
Re: [Vo]:Macedonio Melloni's 1846 Moonlight Experiment
I think Melloni's detector was a homemade thermocouple and probably the best one for the time. The thermalelectric effect- on which a thermocouple depends - was still pretty new at the time having been discovered in the 1820s by Seeback (who incidently helped Goethe write his book on a colour theory of light). Harry On Mon., Jan. 17, 2022, 5:26 p.m. MSF, wrote: > One wonders what Melloni's detector was. Very sensitive was Edison's > tasimeter, which from what I've read could detect radiation from individual > stars at the prime focus of a telescope. > > ‐‐‐ Original Message ‐‐‐ > > On Monday, January 17th, 2022 at 2:47 PM, H LV > wrote: > > > The first person credited with detecting heat from moonlight was > > > > Macedonio Melloni in 1846. Below is a brief description of the > > > > experiment from "Infrared metaphysics: the elusive ontology of > > > > radiation. Part 1" by Hasok Chang , Sabina Leonelli. > > > > (Btw, I have read elsewhere that the experiment was performed on top > > > > of Mount Vesuvius rather than on his apartment balcony. Scientific > > > > folklore perhaps?) > > > > There is a link below of a video described as a reconstruction of > > > > Melloni's experiment. However it is only a laboratory demonstration > > > > using an electric burner as a source of infrared radiation, but it > > > > does use Melloni's large fresnel lens which is worth seeing. If the > > > > temperature change observed by Melloni was the same as in the video, > > > > then he observed an increase of only about 0.25 degrees. > > > > begin quote: > > > > < > > > a magnificent lens out to the balcony of his apartment in Naples. He > > > > had just received the lens, one meter in diameter and the finest he > > > > had acquired so far for the Osservatorio Metereologico then under his > > > > direction. Melloni expectantly trained the powerfully focused > > > > moonlight on his 'thermomultiplier', the most sensitive thermometer > > > > yet known to science. To his delight, the thermomultiplier needle > > > > swung immediately on receiving the light. Over the ages moonlight had > > > > been considered the archetype of 'cold light', famously listed under > > > > the heading of 'negative instances of heat' in Francis Bacon's > > > > analysis of thermal phenomena designed to illustrate the methods of > > > > the new inductive science in the seventeenth century. Marc-Auguste > > > > Pictet in the late eighteenth century focused moonbeams into a bright > > > > light, but still detected no heat. Now Melloni had finally shown the > > > > fallacy of the old opinion. Only moments later, however, Melloni's > > > > delight turned into puzzlement as he noticed that the direction of the > > > > needle-swing indicated a cooling of the thermometer by the moonlight. > > > > That would not do. Melloni considered possible sources of error, made > > > > calculations, and cajoled the instruments, repeating the trials until > > > > he managed to produce a repeatable detection of a positive heating > > > > effect. > > > > This was not a frivolous experiment. Melloni was at the height of a > > > > productive research career that earned him the epithet of 'the founder > > > > of the science' of radiant heat, even 'the Newton of heat'. He made > > > > the moonlight experiment with a very specific purpose in mind: Melloni > > > > needed moonlight to have heat, in order to uphold his recent > > > > conversion to the view that illumination and radiant heat were both > > > > effects of one and the same cause. The radiation of heat (unmediated, > > > > near instantaneous transfer of heat) had been the subject of active > > > > research at least since about 1790, but the nature of radiant heat had > > > > still not been elucidated thoroughly. Melloni's importance in the > > > > history of science now rests mostly on his contributions toward the > > > > identification of radiant heat as long-wavelength light, but curiously > > > > he had spent the 1830s piling up experiment after experiment that went > > > > against the idea that 'obscure radiant heat' was 'invisible light'. > > > > His experimental arguments had convinced many others to turn away from > > > > the apparently absurd notion of non-illuminating light.>> > > > > end quote > > > > a reconstruction of a historical experiment > > > > https://youtu.be/iDcy21D6LLc > > > > Harry > >