DR. HERSCHEL TO SIR J. BANKS.
The last time I was in town, you expressed a wish to see my observations on the comet which my sister, Caroline Herschel, discovered in the evening of the 21st of last December, not far from β Lyræ.
As she immediately acquainted the Reverend Dr. Maskelyne and several other gentlemen with her discovery, the comet was observed by many of them. The Astronomer Royal in particular having, I find, obtained a very good set of valuable observations on its path, it will be sufficient if I communicate only those particulars which relate to its first appearance, and a few other circumstances that may perhaps deserve to be noticed.
Dec. 21st, 1788.—About 8 o'clock I viewed the comet which my sister had a little while before pointed out to me with her small Newtonian sweeper. In my instrument, which was a ten-foot reflector, it had the appearance of a considerably bright nebula, of an irregular round form, very gradually brighter in the middle, and about five or six minutes in diameter. The situation was low, and not very proper for instruments with high powers.
Dec. 22nd.—About half-after 5 o'clock in the morning I viewed it again, and perceived that it had moved apparently in a direction towards δ Lyræ, or thereabout. I had been engaged all night with the twenty-foot instrument, so that there had been no leisure to prepare my apparatus for taking the place of the comet; but in the evening of the same day I took its situation three times. . . . .
In every observation I found the small star which accompanies β Lyræ exactly in the parallel of the comet.
These transits were taken with a ten-foot reflector, and the difference in right ascension, I should suppose, may be depended upon to within a second of time. The determi-
