“Necessarium est autem veteres ortus cometarum habere collectos. Deprehendi enim propter raritatem eorum cursus adhuc non potest, nec explorari an vices servent et illos ad suum diem certus ordo producat”
[It is essential that we have a record of all the appearances of comets in former times. For, on account of their infrequency, their orbit cannot yet be discovered or examined in detail, to see they observe a periodical interval and whether their reappearance on a fixed day could be the result of certain cause] {Seneca, 60AD}
The text above is an excerpt from this book:
The vast ‘Theatrum Cometicum’ (The Theatre of Comets) was published in Amsterdam in 1668 and includes about 80 lavish engravings (a great many of them are double-page fold out illustrations). It provides accounts of over 400 comet sightings throughout history and in discussing their meaning, [Polish astronomer Stanislaus] Lubienietzki essentially helps usher in a more astronomical rather than astrological approach to the study of comets.
Link to more text and scanned images pages, taken from the wonderful old-book blog Bibliodyssey. The editor adds,
The whole of ‘Theatrum Cometicum’ is available online at the National Digital Library of Poland. Also known as Biblioteka Narodowa, this digital library deserves special mention. In addition to having a large selection of books in page image format, the interface is one of the best I’ve seen.