if bonfires are stars

The following passage from Thomas Hardy's The Return of the Native caught my attention:

The bonfire was by this time beginning to sink low, for the fuel had not been of that substantial sort which can support a blaze long. Most of the other fires within the wide horizon were also dwindling weak. Attentive observation of their brightness, colour, and length of existence would have revealed the quality of the material burnt, and through that, to some extent the natural produce of the district in which each bonfire was situate.

If you take the bonfires as representing stars, the passage works as a metaphor for astronomical spectroscopy. Did such discipline even exist when Hardy wrote the novel?