This Book (as the Title it self intimates) undertakes two things. _First_, To give an Account of the _Second_ of the two late Comets, which appeared, when the _other_ was scarce extinct; Concerning which, the Author doth, from the Observations made by himself with a _Sextant_ of 6 foot, and divided into _minutes_ and _seconds_, assign _both_ its true place (as well in respect of the _Ecliptick_ as the _AEquator_) _and_ its proper motion; Adding a fair Delineation of its Course, together with the genuine Representations of its _Head_ and _Train_, in each day of its apparition; and subjoyning a General Description and Discourse of some of the more notable _Phenomena_ thereof. It was first seen at _Dantzick_ by the Watchmen, the 5th of _April_ st. n. 1665. and then observed by the _Author_ from _April_ 6, about 11/2 of the Clock in the morning, till _April_ 20 at 3. in the morning. During which time, it went with a reasonable velocity; making 46 deg. in its Orb, _according to the Order of the Signs_, moving from the _Breast_ of _Pegasus_, towards the _Head_ of _Andromeda_, and the _Left Horn_ of _Aries_; having, as 'tis presumed, taken its rise from above _Sagittary_, and run through the _Breast_ of _Antinous_, under _Aquila_ and the _Dolphin_, to the said _Pegasus_; and so on, as is already expressed. The _Head_ of it is in the Book described of a Colour like that of _Jupiter_, all along much brighter than that of the former Comet, though of a somewhat less magnitude; having in its middle onely _one_ round, but very bright and big _Kernel_ or Speck, resplendent like Gold, and encompassed with another more dilute and seemingly uniform matter: its _Tail_ being at first, about 17. deg. and afterwards 20. and sometimes 25 deg. long, and divaricated towards the End. _Next_, it is observed, that though this Star did afterwards slacken its pace, yet it retained the vividness of its Colour, both of the _Head_ and _Train_; the _Head_ especially, keeping at the time as well of the last observations, as of the {302} first, the brightness of its single _kernel_, though the environing more dilute matter were then almost all lost; it being, according to the Author, more and more attenuated, and grown narrow, the nearer the Star approached to the Sun.