Royal Astronomical Society. 301 



1. A Letter from S. C. Walker, Esq., to Sir J. F. W. Herschel. 

 Communicated by Sir John Herschel. 



"Philadelphia, May 23, 1843. 



" Sir, — From the observations made at the High School Observa- 

 tory, from March 11th to April 10th, the earliest and latest dates 

 at which the place of the nucleus was measured, we have computed 

 the elements of the orbit on the model of Gauss's Theoria Motus, 

 without making any hypothesis respecting the particular conic sec- 

 tion in which the comet moves. The result has been as follows : — 



Perihelion passage, February 27 d '5893933 Greenwich mean time 



Longitude of the perihelion.... 280 44 3-7} Mean March 30 

 Longitude of the ascending node... 15 57 o'Z J n 



Inclination 34 19 52-0 



Perihelion distance 00410369 



Gaussian angle % 2°26'12"-05 



Eccentricity, sec. % 1*00090495 



Mean sidereal daily motion 1 59 "*58936 retrograde. 



" The normal places used were — 



March 20'5. March 30*5. April Q'5. 



Mean time, Mean time, Mean time, 



Greenwich. Greenwich. Greenwich. 



From the app* equinox Geo. R.A. 46 4 38-4 59 51 1-2 68 56 41-6 



Decl. —9 9 45-5 -6 36 32-5 —4 45 357 



Errors of the hyperb. ephem. R.A. —0-6 +0*0 —0-6 

 Decl. +07 —10 +0-3 



" Our observations were made with a 9 -feet Fraunhofer, power 

 75, and with a Fraunhofer filar micrometer. The places of the stars 

 used for comparison were taken from the Histoire Celeste and Bessel's 

 Zone Observations. A small error in our measures, or in the star 

 catalogues, in the declination of the comet, causes a great change in 

 the elements. Still, allowing to that source of error all the weight 

 to which it is entitled, the orbit comes out an hyperbola, and the 

 perihelion point is either in a tangent to the sun, or as nearly so as 

 physical circumstances will permit. 



" I have the honour to be, &c, 



'* Sears C. Walker." 



2. Observations of the Comet. By Captain Tucker, R.N., Com- 

 mander of H. M. Ship Dublin. Communicated by the Lords Com- 

 missioners of the Admiralty. 



The comet was first seen on the 3rd of March, and observations, 

 of which the following is a tabular statement, were made from the 

 4th to the 26th of March :— 



Day and ship mean 

 time of observations, 



Ship's 

 longitude. 



d h m s 

 Mar. 4, 6 58 26106 



7 4 28 



0W, 



5,7 57107 17 



Ship's 

 latitude. 



8 10S 

 11 2 



Observed 



altitude of 



comet. 



7 30 



Distance of 

 comet from 

 known stars. 



Names of 



stars of 



comparison. 



Length 

 of tail. 



72 44 ORigel 



48 44 30Fomalhaut 

 f47 28 30!«Eridani 

 166 16 OJAldebaran 



