518 Royal Astronomical Society. 



The resulting longitude is the mean of nine partial results, de- 

 duced from observations included between June 24, 1842, and May 

 4, 1843. The mean of these results gives 27 s, 38 west of Green- 

 wich, the extreme difference being S *82. 



From six partial results, obtained between November 12, 1842, 

 and January 4, 1843, the latitude of the east end of the terrace was 

 found to be 51° 30' 34"'9 north ; the extreme difference being 3"'4. 

 Whence the latitude of the apartments of the Society results 

 51° 30' 38"-3 north. 



Particulars of the observations are given in the Monthly Notices, 

 in which also is an additional communication from Professor Hen- 

 derson respecting the comet discovered by M. Faye. 



January 12, 1844. — The following communications were read : — 



I. On the Advantages of employing Large Specula and Elevated 

 Situations for Astronomical Observations. By C. Piazzi Smyth, 

 Esq. Communicated by Captain W. H. Smyth, R.N. 



The author adverts to methods proposed by Mr. H. F. Talbot for 

 the multiplication of copies of specula by means of the electrotype, 

 and for observing astronomical objects with a telescope absolutely 

 fixed, by means of a revolving plane mirror, which methods he con- 

 siders might, if carried out, produce great improvements in astro- 

 nomy. Amongst the advantages of the latter method he enumerates 

 the following, arising chiefly from the unlimited focal length which 

 it would be possible to give to the mirror : — first, the obviation of 

 the necessity of an accurate parabolic shape for the reflector ; se- 

 condly, the magnifying of the image without distortion or colour ; 

 thirdly, the small effect which inaccuracies of the screw of the mi- 

 crometer would produce, eye-pieces of low power being employed ; 

 fourthly, the elimination of errors dependent on the contraction or 

 expansion of the tubes of telescopes ; and lastly, the advantage of 

 having the eye in a fixed position. 



The author then enlarges on the advantages which would attend 

 the use of such a fixed telescope if placed on the slope of a high 

 mountain, with the object-mirror and the eye-piece fixed on piers, 

 and separated by a considerable interval, the mirror being beneath. 

 The Nilgherry hills in India he instances as being favourable for the 

 purpose, the climate being particularly well suited for astronomical 

 observations. He then answers the obvious objection of the impos- 

 sibility of reflecting objects from every part of the heavens to the 

 speculum, by assuming that it would be most advantageous for as- 

 tronomical science that every observatory should confine itself to 

 those classes of objects which its geographical position enables it 

 most readily to command. He finally dwells upon the cheapness of 

 the labour of computation in India, arising from the circumstance of 

 the great number of Brahmin priests who are willing and competent 

 to undertake the labour for a very trifling remuneration. 



II. Observations of the Planet Uranus, made in the year 1843. 

 By C. Rumker, Esq. Communicated by Dr. Lee. 



The observations extend from September 10 to October 31. 

 They are corrected for refraction, but not for parallax. 



