404 Additional Notes. 



the heavens in which all die planets perform their revolutions, 

 I'iie period of its revolution is four years, eight months, and three 

 days. 



The orbits of these two planets are nearer together tlian those 

 of any others in our system. In its distance from the sun Piazxi 

 varies from 21 to -25, and Gibers from 2/ to 28, taking tlie distance 

 of the earth as the standard, and estimating it at 10. 



Beside the discoverers, Herschell, de la Lande, Delambre, 

 and Burckhardt, have particularly distinguished tliemselves in 

 observing the phenomena, and in calculating tlie elements, of 

 these planets. — Mr. Herschell proposes to designate these celestial 

 bodies, for the present, by the term " Asteroids." 



Note C'2), p. 79. — Catalogues of stars are of two kinds, either 

 aft collected into certain figures called Constellatiom, or according 

 to their rirrht ascensions, or, in other words, according to their 

 order in passing over the meridian. 



The fust specimen of this latter kind of catalogue, that is, ac- 

 cording to the order of the right ascensipns, was tliat published by 

 de la Caille, in 1755. It contains the right ascensions and decli- 

 nations of 307 stars, adapted to the beginning of tlie year 175O. 

 In 1757 the same gre?t astronomer published his Astronomict Fun^ 

 daintnta, containing a catalogue of the right ascensions and decli~ 

 nations of 398 stars. And in 17^3, the year after his death, was 

 published the Cahim Australe Stellifcnim, also by the same autlior, 

 containing a catalogue of the places of 1942 stars. 



In the yautical Ahnanack for 17/3 is given a catalogue of 38/ 

 stars, in right ascension, declination, longitude, and latitude, 

 derived from the observations of the celebrated Dr. Bradley, astro- 

 nomer royal of Great Britain, and adapted to the beginning of the 

 year 176'0. 



In J 775 was published a catalogue among the papers of the late 

 Tobias Mayer, containing the right ascensions and declinations of 

 C)i)S stars, which may be occulted by the moon and planets, 

 adjusted to the year \75(5. 



At the end of the first volume of " Astronomical Observations 

 made at the Royal Observatory at Greenwich," published in 

 177<>, Dr. Maskelyne, the present astronomer royal, has given a 

 catnlo'jjue ol the places of 34 principal stars, in right ascension, 

 and north polar distance, adapted to the beginning of the 

 }far 1770. 



In 1782, prof. Bode, of Berlin, published a very extensive cata- 



