want of sufficient motion at that time. He examined her at that time
with a power of 460, but could not distinguish anything in her appearance different from surrounding stars of equal brightness.
On the 21st of May, when he had learned her position more pre- cisely from the Astronomer Royal, he observed her again with the same power, but could discern no appearance of a planetary disc.
On the 22nd he perceived her to have moved since the preceding evening, and now examined her with increased powers of 460, 577, and 636, but could find no difference between the planet and a fixed star, the 463rd of Bode’s Catalogue.
Since Vesta thus bears to be examined by high magnifying powers without apparent enlargement of her disc, which is the test by which Dr. Herschel formerly determined the apparent discs of Ceres, Pallas, and Juno, to be spurious, he considers her as belonging to that formerly unknown species of celestial bodies which he has termed asteroids.
May 24th.—Dr. Herschel compared Vesta with the Gregorian planet, and found that with a power of 577 her apparent disc was about one ninth or one tenth as large; and with his 20-feet reflector, of 18% inches aperture, she had no surrounding atmosphere or nebulosity.
Dr. Herschel’s observations on the comet, which follow, were con- fined to three days, January 27, January 31, and February 1. It was near the electrometer of the constellation, called by Bode Machina electrica. Its coma was of an irregular round form, extending six or seven minutes in diameter. -
Upon revising his observations of sixteen telescopic comets, Dr. Herschel remarks, that fourteen have been without any visible solid body in their centre, and that the other two had but an ill-defined small central light, which did not deserve the name of a disc.
The experiments, which form the subject of the present communication were undertaken, not only on account of the difference between the estimates that have been made of the quantity of carbon in carbonic acid, but because those of Guyton de Morveau, which are most frequently preferred at this time in various systems of chemistry, appeared liable to many objections, from the manner in which they were conducted; while the original experiments of Lavoisier, on the contrary, appear to have been performed with much accuracy, and had moreover been confirmed by Mr. Tennant in his researches on the nature of the diamond.
The design of the authors was to consume certain known quantities of diamond and of other carbonaceous substances in oxygen gas; for which purpose it had been originally their intention to employ
