Mr. Flamstead's Account of His Observations of the Late Comet, Sent in a Letter to the Publisher, Greenwich, May 18. 1677

I have this day received a Note from Sr. Jonas Moore, in which he informs me, that you have received Papers concerning the late Comet both from Mr. Hevelius and Mr. Cassini, and that you desire to know what I observed of it. I am glad to hear you have accounts of it from two such able persons, who having observed and made theories for the Comets which appeared near the same place twice of late at twelve years interval, viz in 1653, and 1665, may best inform us, what conformity there is betwixt the Motions of this and them, and whether it may probably be the same returned hither after two revolutions; or another: My Observations of it, by reason of our cloudy Nights, were so few, that I can determine nothing from them; however perhaps they may be of use to others, who had more frequent opportunities, and therefore such as they are, they are at your service. The first time that the Comet was taken notice of with us, that I can hear of, was about the middle of our Easter week; I believe it might have been observed long before, had not the unwonted cloudiness of our Heavens (which has permitted me to observe but 4 of almost 50 appulses of the Moon and Planets to fixed Stars foreseen hitherto) prevented. The first certain notice I had of it was on April 21. I waited the rising of the Comet; but immediately after midnight the Heavens were over- spread with Clouds and continued so till Sunrise, next Morning, preventing me of my desires. The next Night April 22. I again waited for its rising, the Heavens being now exceeding serene and clear: at about 2 a Clock after the Midnight following I saw the Tail raised almost perpendicular to the Horizon; soon after the Head appeared through a thin vapor, from which the Tail pointed as near, as I could guess, upon the * in the knee of Cassiopea, its length being about 6 degrees, and breadth at the top about 7 or 8 minutes. Viewing the Head with a Telescope of 16 foot, I found it was not perfectly round, but indented, and not near one minute diameter. Afterwards I hastened to measure its distances from several fixed Stars, which were as follow: April 22. | h. | o | |----|---| | 14.44.00 | its head and the foot of Androm. Alam. 11.26. | | 47.15 | that distance repeated 11.26.50 | | 55.03 | its head from Capella 31.01.15 | | 59.10 | repeated 31.01.24 | | 15.12.02 | its head from Algol in Medusa's 8.16.54 | | 21.22 | from Mirach 19.35. | | 27.54 | from Alamech again 11.33.30 | | 15.36.20 | from Capella again 30.59.45 | At h. 15.21 p.m. the height of the Comet was about 5° 1 degr. therefore the distance of the head of the Comet from Algol corrected by refraction, —— 8° 19' from Mirach, —— 19° 37 And admitting with Mr. Hevelius the place of Mirach now in γ 21° 40' 34", with North latitude 25° 57', its distance from Algol will be 23° 42' 40", and the place of the Head of the Comet in γ 14° 48", with North latitude 17° 08'. At 15h 28' I state the correct distance of the Comets head from Capella 31° 00', from Alameck 11° 40'; and therefore its true place in γ 14° 50", with North latitude 17° 06' 25", agreeing very well with the place derived from the former distances from two other and different Stars. The Tail was not, it seems, directly opposite to the Sun, for the Suns place was now γ 30° 07'; but the Comet being in 14° 47' of the same Sign, that is 1° 40' in consequence of the Sun, the Tail ought, if it had been exactly opposite to the Sun, to have lain in consequence of the head; but the knee of Cassiopea is now in $13^\circ 24'$ in antecedence of the Comet, whose Tail lay not therefore in consequence, but in antecedence of the line passing through its head and the Sun, at about an angle of 10 degrees. Next Night, being that following the 23 of April, I again waited for the Comets rising; but the Heavens were thick of scattered Clouds, and most where the Comet rose, so that I almost despaired of seeing it; till about $\frac{3}{4}$ of an hour after two I saw its Tail, which appeared much shorter than last morning through a break of the Clouds; which soon after opening wider I saw the head too, and halting I measured its distance. April 23 at $14^h\ 51^m$ p.m from Mirach $21^\circ 09'$; but before I could get the plain of the Sextant to Algol, the Clouds came over the Comet again, and I could see it no more. Hence, and from a course Observation of it sent me by an ingenious Friend, I found its motion was direct, and its latitude decreasing. I hoped nevertheless I might see it again in the Evenings following, and waited for it; but though they proved sometimes clear I could never find it, and I believed, that hence forward to us it would be unobservable. An Account of some Books: I. The Natural History of OXFORDSHIRE, being an Essay toward the Natural History of ENGLAND: By Robert Plot, LL.D. Printed at the Theater in Oxford, 1677, in fol. The worthy and learned Author of this Work, having very generously undertaken to make a fuller and stricter survey of the Natural and Artificial things of England, than hath been made hitherto, and being induced to this undertaking by the consideration of advancing thereby both the knowledge of Nature, and the business of Trade; hath begun to execute this Noble design by giving us a very particular account of what occurred to him, for the most part upon his own personal enquiry, in Oxfordshire. An attempt so considerable, that if it were pursued by fit persons all over the World with care, judgment and diligence, would in time produce a just History of Nature, and furnish both the Philosopher with good Materials to work with, and generally all sorts of men with the pleasant and useful knowledge of the riches and wonders of the World.