IG'2 



tention was again called to it by Dr. Briukley's late communication. 

 By reference to an annexed table, it appears that the greatest error 

 in a series of ten observations, made with the transit, could not have 

 been more than O'"03, and consequently it is not probable that the 

 error in fifty observations should have exceeded half that quantity. 

 Taking, however, every circumstance into consideration, it is possible 

 that the whole parallax of a Aquilse may have amounted to half a 

 second, which is about a tenth part of that assigned to this star by 

 Dr. Brinkley. The author, however, proposes to continue the inves- 

 tigation ; and when his observations shall have been sufficiently mul- 

 tiplied, promises to communicate the result to the Society. 



OM the Parallax of the Fixed Stars in Right Ascension. By John 

 Pond, F.R.S. Astronomer Royal. Read May 28, 1818. [Phil. 

 Trans. 1818, p. 481.] 



This paper is intended as an appendix to a former one on the same 

 subject. The author extends his investigation to a few more of the 

 principal fixed stars. He divides the results of any one star into two 

 parts ; first, alternately or accidentally, and also according to the law 

 of parallax ; and as no greater difference is observable in the latter 

 than in the former case, it is demonstrable that parallax has had no 

 sensible effect on the observation. He next inquires what may be 

 the magnitude of the parallax that might be concealed by the acci- 

 dental error of observation. Without entering into a rigorous com- 

 putation on the laws of probability, he conceives that it may be in- 

 ferred by inspection, that it is almost impossible that the longer axis 

 of the ellipse, described by the brightest fixed star, can exceed 0"'6, 

 and it is very improbable that it should amount to half as much ; and 

 as this quantity can never derange the mean place of a star 0"' 1 in 

 declination, it is evident that all attempts to determine the parallax 

 by a meridian instrument of any description must be utterly hope- 

 less, 



An Abstract of the Results deduced from the Measurement of an Arc 

 on the Meridian, extending from Latitude 8 9' 38"'4, to Latitude 

 18 3' 23"-6 N., being an Amplitude of 9 53' 45"'2. By Lieut. 

 Colonel William Lambton, F.R.S. 33rrf Regiment of Foot. Read 

 May 21, 1818. [Phil. Trans. 1818,^. 486.] 



The author, at the commencement of this paper, refers to the 12th 

 volume of the Asiatic Researches, in which there are detailed ac- 

 counts of two complete sections of an arc on the meridian, measured 

 by him in prosecuting the Trigonometrical Survey of the Peninsula 

 of India, The first is comprehended between the parallels of Punnae, 

 a station near Cape Comorin, in latitude 8 9' 38"'39, and Patchi- 

 polliam in Coimbetoor, in latitude 10 59' 48"'93. The second is 

 comprehended between the parallels of Patchipolliam and Namtha- 

 bad, a station near Gooty in the ceded districts, in latitude 1 5 6' 0"-21. 



