Fig. a. A manifest species of Pediculus Marinus crumped up.
b. A Seed-vessel, given me by Mr. Da Costa, found in a clay-pit in Staffordshire.
c. Cocculus Indicus.
LII. Observations upon the Comet that appeared in the Months of September and October 1757, made at the Royal Observatory by Ja. Bradley, D.D. Astronomer Royal, F.R.S. and Member of the Royal Academy of Sciences at Paris.
Read Dec. 22, 1757.
I Deferred to give an account of my observations upon the Comet that hath lately appeared, till I could settle the places of the stars with which it had been compared; several of them not being inserted in the British catalogue, and those which are, requiring some small corrections, which I have since made from my own observations.
When I first discovered this Comet, it appeared to the naked eye like a dull star of the 5th or 6th magnitude; but viewing it thro' a seven-foot Telescope, I could perceive a small Nucleus (surrounded, as usual, with a nebulous atmosphere), and a short tail extended in a direction opposite to the sun.
Some small stars then appearing in the field of the telescope with the Comet, I measured its distance from them with a Micrometer; and on September 12d at 16h 2' mean time, I found it to be 1° 13' 5" distant from a small star, whose right ascension was afterwards found to be 89° 49' 40" and declination 36° 11' 30" north: and near the same time the Comet was observed to be 43' 10" from another star, whose right ascension was 90° 20' 0" and declination 35° 12' 0" north.
Hence I collected, that the Comet's right ascension was 89° 29' 10" and its declination 35° 0' 20" north.
September 13d 12h 37' mean time (which is likewise made use of in the following observations), the Comet had the same right ascension with a small star, whose right ascension was 93° 5' 30" and declination 34° 36' 40" north; and it was about two minutes more northerly than the star. Hence the Comet's right ascension was 93° 5' 30" and its declination 34° 38' 40" north.