598 Royal Astronomical Society : — Mr. Main on the 



1 . Abstracts of theoretical papers which have appeared on the 

 subject of annual parallax. 



2. A statement of the results of observations which have been 

 made since the time of Bradley for the purpose of detecting par- 

 allax. 



3. A review of the results of contemporaneous astronomers on 

 this subject. 



4. A discussion of Bessel's observations and results. 



Under the first division, he gives abstracts of the . following 

 papers : — 



A Memoir by Clairaut. — Memoires de 1' Academic, 1739, p. 358. 



A Memoir by Sir W. Herschel.— Phil. Trans. 1782, Ixxii. P. I. 

 p. 82. 



A Memoir by Schubert. — Berliner Astronomisches Jahrbuch, 

 1796, p. 113. 



A Memoir by Sir J. Herschel on the Detection of Parallax by 

 the Variation of the Angle of Position of Double Stars. — Phil. 

 Trans, 1826, P. II. p. 266 ; and 1827, P. I. p. 126. 



A Memoir by Struve, forming one of the introductory chapters 

 to his large work on double stars. 



A discussion by Bessel of Bradley's Observations of Right Ascen- 

 sions of Stars differing by nearly 12''. — Fundamenta Astronomise, 

 Introduction. 



Under the second head he gives, briefly, the results obtained by 

 Piazzi, Calendrelli, Brinkley, Pond, Bessel, and Struve, referring to 

 the following works : 



For Piazzi and Calendrelli : — 



Memoirs of the Italian Society, vol. xii. 



Calendrelli's Opusculi Astronomichi, vol. for 1806. 



Zach's Monthly Correspondence, vols, xviii. and xix. 



For Brinkley and Pond : — 



Phil. Trans., vols, for 1810; 1817; 1818, P. II.; 1821, P. II.; 

 1823, P. I.; 1824, P. I. and II. 



Memoirs of the Astronomical Society, vol. i. P. II. 



Transactions of the Royal Irish Academy for 1815, vol. xii. 



The Introduction to the Konigsberg Observations for the year 

 1816. 



The Dorpat Observations, vols, i., ii., and iii. 



Under the third head, the following memoirs on the subject are 

 considered : — 



On the Parallax of a Aquila, by Mr. Henry Taylor, Astronomer 

 to the East India Company at Madras. 



On the Parallax of a Lyra, by the Astronomer Royal. — Mem. 

 Ast. Society, vol. x. 



On the Parallax of «' and a* Centauri, by Professor Henderson, 

 Mem. Ast. Society, vol. xi. 



On the Parallax of Sirius, by Professor Henderson*. Not yet 

 printed in the Society's Memoirs. 



[• An abstract of Prof. Henderson's paper will be found in Phil. Mag. 

 Third Series, vol. xvi. p. 148.] 



