Memoirs of the Astronomical Society of London, 215 
and Azimuth Instrument; describing their different Construc- 
tions, the Manner of performing their principal Adjustments, 
and how to make Observations with them; together. with a 
Comparison of their respective Advantages. By Edward Trough- 
ton, Esq., F.R.S., and Member of the American Philosophical 
Society.—II. The Description of a Repeating Instrument upon 
a new Construction. By G. Dollond, Esq. F.R.S.—III. On a 
Method of fixing a Transit Instrument exactly in the Meridian. 
By F. Baily, Esq. F.R.S. and L.S.—IV. On the doubly-refract- 
ing Property of Rock Crystal, considered as a Principle of Mi- 
crometrical Measurements, when applied to a Telescope. By 
the Rev. W. Pearson, LL.D. F.R.S. and Treasurer of this So- 
ciety ——V. On the Construction and Use of a Micrometrical Eye- 
piece of a Telescope. By the Rev. W. Pearson, LL.D. F.R.S. 
and Treasurer of this Society.—VI. On the Construction of a 
new Position-Micrometer, depending on the doubly-refractive 
Power of Rock Crystal. By the Rev. W. Pearson, LL.D. F.R.S. 
and Treasurer of this Society.—VII. Observations on the best 
Mode of examining the double or compound Stars ; together with 
a Catalogue of those whose Places have been identified. By 
James South, Esq. F.R.S. and L.S. Honorary Member of the 
Cambridge Philosophical Society, &c.—VIII. On the new Me- 
ridian Circle at Gottingen. Communicated by Professor Gauss, 
in a Letter to the Foreign Secretary.—IX. On the Solar Eclipse 
which took Place on September 7, 1820. By F. Baily, Esq. 
F.R.S. and L.S.—X. On the Solar Eclipse which took Place on 
September 7, 1820. Communicated in a Letter to J. F. W. Her- 
schel, Esq., Foreign Sebretary, from Professor Moll of Utrecht. 
—XI. On the Comet discovered in the Constellation Pegasus in 
1821. Communicated in a Letter to J. F. W. Herschel, Esy., 
Foreign Secretary, from M. Nicollet of Paris —XI11. On the Comet 
discovered in the Constellation Pegasus in 1821: and on the 
luminous Appearance observed on the dark Side of the Moon on 
February 5, 1821. Communicated in a Letter to J. F. W. Her- 
schel, Esq., Foreign Secretary, from Dr. Olbers of Bremen.— 
XII. On a luminous Appearance seen on the dark Part of the 
Moon in May 1821. Communicated in a Letter to the Rev, 
Dr. Pearson, from the Rev. M. Ward.—XIV. On the Occulta- 
tions of Fixed Stars by the Moon: on the Repeating Circle: on 
the Perturbations, &c. of the new Planets: and Observations of 
the late Comet and of the Planet Vesta. Communicated in a 
Letter to the Rev. T. Catton, F.R.S., from Professor Littrow of 
Vienna.x—XV. On the Places of 145 new Double Stars. By Sir 
William Herschel, President of this Society—XVI. Universal 
Tables for the Reduction of the Fixed Stars. By S, Groom- 
bridge, Esq., F.R.S, and 8.R.A, Nap,—XVIII. Observation of 
the 
