504 PROFESSOR CHALLIS, ON THE DETERMINATION OF THE LONGITUDE 



The chronometer X is that which was used for noting the signal-times. The comparisons 

 were made in two sets to serve as checks to each other : it will only be necessary to give 

 here the comparisons which were made use of, which are generally means between two sets. 



May 16. 



A. m. #. A. m. «. 



12.46.55,5 W = 16.20.51,0 U 

 12.49.31,0 W = 16.28.57,5 X 

 12.53. 2,0 W = 16.29.14,0 H 

 21 .22.14,0 W = 0.57.29,0 U 

 21.23.22,5 W = 1. 4.11,5 X 

 21.29.27,5 W = 1. 7. 1,5 H 

 21.32.25,5 W = 1.13.16,0 X 



May 17. 



A. Ml. s. 



2.10. 0,0 W 1 

 2.13.20,0 W = 

 2.17.44,0 W = 

 7.35. 0,0 W = 

 7.37. 4,5 W. 

 7.40.11,0 W 1 

 9.46.43,5 W 1 

 9.47.39,0 w . 

 9.50. 5,5 W 

 10.31. 5,0 W 

 10.46.30,0 W 

 10.48.46,0 W 

 10.52.38,0 W 1 

 12. 7.22,5 W 1 

 12. 9.33,5 W . 

 12.57.41,5 W 



A. m. g. 

 5.51.35,0 X 



5.51.39,0 H 



5.53.44,5 U 



11.14.10,0 H 



11.19-32,0 X 



11.17. 1,0 U 



13.23.53,0 U 



13.30.27,5 X 



• 13.29.37,0 H 



: 14.14. 0,5 X 



14.29.28,0 X 



1 14.26. 5,0 U 



1 14.35.37,0 X 



15.50.33,5 X 



15.47. 5,0 U 



1 16.37.43,0 H 



May 17. 



ft. tn. $. k. m. $. 



12.59.34,0 W = 16.42.55,5 X 

 13.11.25,0 W = 16.49. 6,0 U 

 13.18.10,5 W = 17. 1.35,0 X 

 13.22.49,5 W = 17. 2.55,0 H 

 13.29.25,5 W = 17. 9.32,0 H 

 13.36.35,0 W = 17.20. 2,5 X 



May 18. 



A. m. s. 



9.24.51,5 W 

 9.38. 2,0 W = 

 9.41. 9,0 W = 

 9.44.44,5 W = 

 9-49.25,5 w = 



10.34.24,5 W = 

 10.40.57,0 W = 

 10.45.19,0 W = 

 10.48.27,5 W = 

 12. 6. 8,0 W = 



12. 9-24,0 W = 



13. 4. 4,5 W = 

 13. 4.39,5 W = 

 13. 8. 0,0 W = 

 13. 8.37,0 W = 

 13.11.26,0 W = 

 13.11.56,0 W = 



A. m. t. 

 13. 8. 8,0 H 



13.24.42,5 X 



13.27.50,0 X 



13.25.32,0 U 



13.32.46,0 H 



14.15.19.5 U 



14.21.53,0 U 



14.32.11,0 X 



14.35.20,0 X 



15.53.13,0 X 



15.50.33,5 U 



16.47.56,0 H 



16.48.31,0 H 



16.55.16,0 X 



16.55.53,0 X 



16.52.45,0 U 



16.53.15,0 U 



From the above comparisons, and the errors of Hardy given by the method (A), the 

 following errors of W on Cambridge mean time, and of X and U on Cambridge sidereal time 

 were calculated. 



Mean Time. 



A. m. m. 1. 



May 16. 12.52 W fast 1. 1,70 



21.28 1. 3,98 



17. 2.12 1. 5,29 



7.34. 



9.49. 



12.57. 



1. 6,78 

 1. 7,31 

 1. 7,93 



Mean Time. 



h. m. m. a. 



May 17. 13.22 Wfast 1. 8,03 



13.28 — 



18. 



9-24. 



9-48. 

 13. 3. 

 13. 3. 



1. 8,10 

 1.13.11 

 1.13,13 

 1.13,89 

 1.13,98 



