Royal Astronomical Society, 301 



Helix hispida, the synonyms of two distinct species are in the " Irish 

 Testacea " again appropriated to one. These are the Helta: planata 

 of Maton and Rackett and the H. carinata of Montagu, and as these 

 have not severally been given in any catalogue of the shells of Ire- 

 land, and my cabinet contains specimens of both species collected 

 there, one or other, the Planorbis lutescens of Lamarck, or P. cari- 

 natus of Draparnaud (to adopt modern names), remains now to be 

 added. — Valvata Planorbis, Drap. 



A beautiful species ofLimneus, collected in the South of Ireland 

 by William Henry Harvey, Esq., of Limerick, and presumed to be 

 new to science, was also characterised by Mr. Thompson. It ap- 

 proximates the L. glutinosus more nearly than any other British 

 species of this genus. 



A notice of an addendum to this paper subsequently read to the 

 Society will be found in our Number for July, p. 70. 



ROYAL ASTRONOMICAL SOCIETY. 



April 11. — The following communications were read : — 



I. Places of the periodic Comet of 6*7 years, or Comet of Biela, 

 deduced from the Observations of Sir John Herschel at Slough, 

 and of Mr. Henderson at the Cape of Good Hope. By Mr. Hen- 

 derson. 



The positions of the stars with which the comet was compared 

 were obtained partly from the catalogues of MM. Pond and Bessel, 

 but chiefly from observations made at the Cape Observatory. 

 Founded on these determinations, there are given — the comet's 

 apparent geocentric right ascension and declination on September 

 23rd and 24th, and November 3rd and 4th, 1832, deduced from Sir 

 John Herschel's observations — and on November 18th, 22nd, 23rd, 

 and 27th, December 26th and 31st, 1832, and January 1st, 2nd, and 

 3rd, 1833, deduced from the observations of Mr. Henderson. 



II. Various Observations made at the Observatory, Cape of Good 

 Hope, in April and May 1833. Communicated by Mr. Henderson. 



1. Observed Transits of the Moon and Moon-culminating Stars. 

 By Lieut. W. Meadows, R.N. 



2. Observations of the Moon and Stars made with the Mural 

 Circle, on April 29th, 1833. 



3. Observation of a Lunar Occultation of n Geminorum, made on 

 April 24th, 1833. 



This additional series of observations made at the Cape Observa- 

 tory by Messrs. Henderson and Meadows, is a continuation of those 

 already communicated. (See Monthly Notice for June 1833.) 



III. Results of a comparison of various Observations of Mars made 

 at Cambridge, Greenwich, and the Cape of Good Hope, for the de- 

 termination of the Sun's Parallax. By T. Henderson, Esq. In a 

 Letter to Professor Airy, dated Nov. 11th, 1833. 



Mr. Henderson has compared various observations made at Cam- 

 bridge, and at Greenwich with both circles, with his own made at 

 the Cape of Good Hope ; and has deduced the correction of the 

 declination of Mars, as given in the Berlin Ephemeris. The results 



