The comet mentioned by the article is Biela's Comet, first recorded in 1772 by Montaigne and Messier and finally identified as periodic in 1826 by Wilhelm von Biela. The comet was observed to have split in two in the 1840s and has not been seen since 1852.
BY THE WAY
A theorist who argues that comets cause floods notes that the comet whose appearance coincided with the Holmfirth flood split in two and has never been seen since. A pleasing instance, and a rare, of remorse among the stars.