14 



MATHEMATICAL and 



" conftrudion as I could. March loth^ this inftrument 

 " was finifhed, and put up out of doors, the Obfervatory 

 ^' not being yet ready. 



y 



" I had, however, for fome weeks before this, with my 

 " ;^6 i. Refrador, obferved eclipfes of Jupiter's fatellites, 

 " in fucha manner that, though my equal-ahitude inftru- 

 " ment was not finij[hed, and confequently I could not fet 

 " my time-peace to the true noon, I fhould neverthelefs 

 " be able to tell the time of thofe eclipfes afterwards, when 

 " the inftrument fhould be ready. For this purpofe, I 

 ^' obferved, almoft every fair evening, the time by the 

 " clock, when the bright ftar in orion difappeared be- 

 hind a fixed obftacle, by applying my eye to a fmall 

 fight-hole, made through a piece of brafs fattened to a 

 ftrong poft. 



i( 



(i 



The Obfervations were as follows, viz^ 



1769. Star difappear- 

 ed, per clock. 



Feb, D, h. m. fee. 

 15 9, %(y. 39 

 %% 8. 58. 5» 

 *4 8- 50. 57 



41 



4 

 16 



11 



44 



Mar. 3 



8. 23. 



1% 



7. 48. 



14 



7. 40. 



17 



7. 29- 



ao 



7. 17. 



ai 



7- 13- 



a8 



6. 45- 



Immer. ift fatel. per 



clock. 

 JFeb. D. h, m. fee. 

 16 14. 24. J 8 



a3 16. 17. 41 



Hence, from column 



3d, the apparent 



times of the two 



immerfions above, 



are, 



Feb. D. h. m. fee. 



16 14. 21. lo 



%% 16. 15. t 



Eq^ual altitudes of Q 



Mar. A. M, P, M, 



©. h. m. fee. h. m. fee. 



8. 58. 5%. a. .56. 52 



0. a. la. a. 53. 32 



10 



S. j6. 40. a. 58. 26 



8. 59- 59- »• 55' 7 



Hence appar. 

 noon, or Q's 



cent, on Mcrid. 



per clock. 



h. tn. fee, 

 II- 57- 37. 



II. 57. l8^ 



" From this time, to May 2othy the clock was altered 

 ^^ feveral times; once taken down and cleaned, removed 

 " back to the obfervatory, and regulated anew. Care was, 



" however, taken to obferve equal-altitudes of the iun, on 

 the days preceding and following any vifible eclipfe of 

 the iftfatellite; when the wheather would permit. 

 *' The whole obfervations, during this period, were 



^^ the following, 



(( 



(( 



Equal 



^>fcf *«r:-^ _ i-rr^i^-:^ — 



