414 Astronomical and Nautical Collections. 



In the CEuvres de Goudin, Paris, an VIII, there is de- 

 monstrated a similar method for solar eclipses, which are the 

 same in principle as occultations of the stars. 



In the Connaissance des Terns for 1806-7, (Additions, p. 

 487,) a paper by M. Chabrol is published upon the ana- 

 lytical method for the calculation of eclipses, in which the 

 principle of computing the parallaxes from the place of the 

 sun or star is followed. In this paper, (which has been 

 translated in Rees's Cyclopcedia, art. Eclipse,) the method is 

 very clearly demonstrated. 



The same method is also followed by Monteiro da Rocha, 

 in Memoires sur VAstronomie pratique, Paris, 1808; by 

 Carlini, in the Milan Ephemeris for 1810, and in Santini's 

 Elementi di Astronomia, Padua, 1819 ; and by Dr. Maske- 

 lyne, in Vince's Astronomy, vol. i., p. 527, second edition. 



The last two authors rest the method upon this principle, 

 that at the immersion or emersion of a star, its true place is 

 the same as the apparent place of the moon's limb, where 

 the phenomenon happens, and consequently the parallaxes 

 being computed for this place, the true position of the point 

 of the limb is obtained, the true distance of which from the 

 centre is the horizontal semidiameter without augmentation. 

 The case of the beginning or end of a solar eclipse may be 

 considered to be the same as the occultation of a star, the 

 moon being supposed to have an apparent or augmented 

 semidiameter, equal to the sum of her real augmented semi- 

 diameter and the semidiameter of the sun ; and the true 

 distance of the point of the fictitious limb from the centre 

 will be equal to the fictitious semidiameter divested of 

 augmentation r that is to say, to the sum of the moon's 

 horizontal semidiameter and of the sun's semidiameter, 

 diminished by its proportional part of the augmentation. 

 Accordingly, several of the authors referred to direct the 

 sun's semidiameter to be diminished by a proportional quan- 

 tity of the augmentation of the moon's semidiameter ; while 

 the computed apparent distance and the moon's semidiameter 

 remain without augmentation. This was noticed in the 

 Quarterly Journal vol. xx., p. 94. 



