the instrument; whilst the proportion applicable to each star was indicated by the table purposely prepared for the latitude of Hartwell. Making due allowance for the lapse of time between the transits, and then applying it to the clock-errors, the difference between the high and low star is divided by the tabular azimuth difference between those two polar distances. The quotient thus obtained is multiplied by the tabular number, and the result is applied to the clock-error. Finally, Finally, the difference in this last column from the clock-error resulting from the selected index-stars, indicates the modification required in the place before assigned to the unknown star. For example, Nat. num. ta 1.748 0:052/ c1.055 +3.828 d 0.973 Rate by Pollux. 29 April +14.63 +11.72 -48 .48 -48 48 7 .8 2 May Lost in 72 hr 28.91=:04 per h'. •216 .288 336 384 Examples of correcting AR. of unknown stars, by two Greenwich stars being assumed as known, a Cyg. and a? Capric. In the following Catalogue of the Hartwell Stars, the left-hand page contains the copy of Mr. Epps's registered observations, forming, as it were, the raw material of the right-hand or opposite page, where the results of reduction are given, and the difference of those results from the well-known Catalogue of the Royal Astronomical Society; the whole being brought up to the epoch 1850 by Mr. Baily's co-efficients. I have given weights, () to 3, on the ultimate determinations, as shewing the comparative value which an investigation of them produced. 1838 3 Oct. 21 Andromeda N. A. a 19.5 40.5 0 0 1.5 22.5 43.6 1:52 - 03:32 29 Ditto 21:0 42:0 0 0 3:3 24.2 45.4 3.18 - 01.63 - 2.41 Rate with a Coron. 5 days before. Rate with $ Aqui. 3 days before. - 2.08 — 2:38 Level W. +0".96. Rate with y Aqui. 3 days be fore. — 2.29 | Level next day E. +0:55. Rate with y Aquilæ 3 days previous. - 2:34 Level on the 5th red, to W. + (s.61. Rate by a” Capr. 9 days after. -- 2.17 Rate with a Capric. 3 days previous. - 2.19 Wrottesley corrects N.A. by + 09:41. Rate with a? Capric. 6 days previous. 2.21 Rate with a Capric. 3 days previous. - 0.79 Rate with a Aqua. 2 days previous. – 1.06 Rate by q Ursæ M., S. P. 2 days previous. - 1.13 Rate with U. M. the pre vious day. Cloudy; mer. mark trem. -- 1.35 Rate with 8 Capr. 2 days previous. -0.16 Wrottesley corrects it by + 15.85. Rate with $ Peg. 2 days previous. 0 Dble star, same AR. – 2:01 Rate by o Peg. 3 days pre vious Az. er. by a Cap. and a Cyg +1".28 and by a Ceti and a Pers. + 0.97. A good night's work. Cik. put forward to.day. — 2.15 Rate with a Aqua. 3 days previous. 2 50 29.0 48 9 2 53 43.8 2:4 21:0 3 02 18:3 38.0 57.8 36.8 56.4 3 02 16:0 35.8 ور 55.5 16:10 - 10:36 - 1.96 Rate with a Peg. 3 days previous. - 2.02 Rate with y Peg. 4 days previous. Level W. + 0".25. 0 The clock was put forward to-day Az. E. +04.27 by a Aqui, and a Cyg. by Epps. 27 Dec. Ditto 14.6 34.2 3 02 54.0 13.7 33.2 53.94 + 27.24 DEDUCTIONS. Star's name. AR. 1 Jan. 1850. Approx. P.D. Daily Wt. Az. correction. Remarks. Ast. C. h. m. 21 Andromeda. a 00 37.93 61 45 Star's compared for daily azim. a Lyræ and mean a Cyg, and a 2 Capric. a Lyr. and mean a Cyg. and a2 Capric. a Lyr, and mean a Cyg. and a2 Capric. a Lyræ and mean a Cyg. and a2 Capric. q Drac. and Fomal. g Drac, and Fomal. q Urs. M. and B Corvi q Drac, and Fomal. g Drac, and Fomal. a Pers. and a? Capric. a Cyg. and a Aqui. a Pers, and a2 Capric. a Pers. and a2 Capric. Arietis 1:35 a Pers. and a2 Capric. Ditto 1.20 a Pers, and y Erid. Ditto 0.21 3 +0:11 a Cyg. and a Aqui. Therm. in clk. case 369. 99 |