ECLIPSE OF THE SUN, JUNE 16, lSOo. 2-99 



Semidiameter corresponding to the constant lunar parallax of the tables. 15' 33" 69 



Correction. . . 1 70 



Constant semidiameter of the 2 . . .... 15 31 99 



Therefore constant diameter of the 3 31 03 98 



From tins statement, it will appear, that the semidiameter 

 of the moon, ascertained in the occultations, may vary 2" on 

 account of the irregularities of the disk of the moon; it may 

 be further remarked, that the periodical variations of the pa- 

 rallax of the moon, by the new tables, are those which Mayer 

 found by his theory, and which differ from the coefficients 

 determined by Laplace. According to the calculations of 

 Mr. Burckhardt, the sum of the periodical differences of 

 the two authors above mentioned, may, under very extra- 

 ordinary circumstances, amount to 7". — In this case the un- 

 certainty of the semidiameter of the moon would be l" 9. 



In the explanation of these tables, it is maintained that M. 

 Burg has diminished the diameter of the moon by 2", but it 

 is easy to see that the diameter of the moon by these tables, 

 is the same as has been determined by M. De Lalande. For the 

 proportion of the horizontal equatorial parallax of the moon, 

 and the. horizontal diameter of the moon according to Burg, 

 is 60: 32' 45" 1. 



According to De Lalande, the proportion between the hori- 

 zontal parallax at Pans and the horizontal diameter of the moon, 

 CO : 32' 4:6" 6, vide the tables of the third edition of his 

 astronomy, printed in. 1797, page 77. 



According to Burer, the constant equatorial parallax. . . =5"' 01" 

 De Lalande, for Paris =56 58 3 



And although the constant parallax of De Lalande referred 

 to the equator differs nearly -4", nevertheless, the constant se- 

 midiameters are the same. 



From the above data, the horizontal diameter of the moon 



corresponding to the constant parallax for Pans, will be, 



,. , p. , , j 32' 46" 6x56' 58" 3 j, n _„ __ 

 according to DeLalande= =31 07 3d 



Burg. . = 3-/4]" lx 57-01--0_ 31 



b CO 



which proves that the results are sensibly the same. 



