Apian observes that the tails of comets are invariably directed from the sun - Observations of Tycho Braihé his views and hypotheses concerning the nature of comets–Kepler regards them as transient meteors, moving in straight lines through space–Galileo shares the opinion of Kepler–Systems of Oassini and Hevelius.

Sixteen centuries passed away between the prediction of Seneca and its full realisation through the accumulated researches of many astronomers and the publication of the Principia, in which Newton demonstrated the law of cometary movements. There is nothing to tell of the history of comets and of systems during this long and dreary period in which the doctrine of Aristotle prevailed, except that it is entirely filled with astrological predictions. Our first chapter contains a résumé of all that the learned have found of interest concerning the apparition of comets and their formidable signification.

Towards the middle of the sixteenth century the movementof the Renaissance, so favourable to letters and the arts, extended its beneficent influence to the science of observation. At the end of the fifteenth century, we find Regiomontanus describing with care the movements of comets, Apian observing that cometary tails are always turned in a direction from the sun; Cardan remarking that comets are situated in a region far beyond the moon, founding his opinion upon the smallness or absence of parallax.