80 



MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



15) 



B. Fl. 1686. 



Flainsteed compared, on three days in April, 1708, the planet Jnpiter with 3 stars of Virgo, as 

 seen in the Historia Cce.lestis, II, p. 518, thus: 



Jupiter 



5 Virgiiiis 



i- (i.e., 10) Virginis 



April 2. 



Time. Zenit dist. 



h. in. 8. 



10 8 48 

 16 52 

 26 33 

 30 51 



47 16 50 



46 11 10 



47 56 50 

 47 34 40 



April 5. 



Time. Zenit dist. 



h. m. 8. o ' " 



9 56 23 47 10 20 



10 5 27 46 10 50 



15 9 

 19 27 



47 55 40 

 47 34 40 



April 6. 



Time. Zenit dist. 



L. m. s. 

 9 50 16 



10 1 38 

 11 23 

 14 17 



o ' 1/ 



47 8 20 



46 10 50 



47 55 50 

 47 34 40 



It is quite niauifest that the last star observed on April 6 was the same as that observed on 

 the other da.vs, viz: Pi. 12i'.lfi, No. 1C88 of the British Catalogue. Already Aliss Hersehel noted 

 this, but that the clock time was put down 1™ 24* too early, and should read 10'' 15™ 41' instead of 

 10'' 14"' 17\ Baily's inspection of the MS. showed the print in conformity with the original. How 

 the mistake may have originated it is quite useless now to speculate about; but it seems not less 

 unreasonable to suspect here the observation of a star now lost. 



16) B. Fl. 1910 (6"). 



There is no star of the sixth magnitude in the place entered in the British Catalogue under 

 the name of 91 Virginis, and which comes from an observation made on May 13, 1703. 



We compute from Miidler's Bradley for 1703 the right ascensions and apparent zenit dis- 

 tances of: 



On page 401 of the Historia Ccelestis, II, are reported the following observations, in agreement, 

 as Baily assures us, with the MS. transcript, the original entry being lost: 



Here the zenit distance of star x agrees with that of 92 Virginis. 



Reducing the clock time for sidereal rate, as in the 4th column, and subtracting the resulting 

 Tfrom the respective light ascensions of the pre 'odiiig table, the column a — Tis formed. The 

 variance shown here would disa[)pear by assuming a correction in the recorded time of +1"" 52= 

 (or of l"" 50», or, perhaps, roundly 2™), and the star therefore very likely was 92 Virginis. No fur- 

 ther conjecture regarding the origin of the error can be made, since, as said, the book with the 

 original entry for this time is lost. 



