Elements of Astronomy. 

 6. Longitude of the ascending Node. 



Mercury 51° 0651 



Venus 83° iy72 



Earth O" 0000 



Mars 53" 3605 



Vesta 114"* 4630 



Juno 190° 1228 



7. Inclination of the Orlit to the Ecliptic. 



Ceres Sg" 9083 



Pallas 191° 7148 



Jupiter .... 109° 3624 



Saturn .... 124° 3662 



Uranus .... 80° 9488 



Mercury 7^ 78058 Ceres 11° 8O68O 



Venus 3° 76g36 Pallas .. . . 38° 46540 



Earth 0° 00000 Jupiter.... 1° 46034 



Mars 2° 05663 Saturn..'.. 2° 77102 



Festa 7° 94010 Uranus.... 0" 85090 



Juno 14° 50860 



The examination of the first two tables here given will 

 show us that the duration of the revolutions of the planets 

 increases with their mean distance from the Sun. Whence 

 Kepler discovered his third fundamental law : namely, 



III. The squares of the times of the revolutions of the 

 planets are to each other as the cules of their mean distances. 

 The ellipses, which the planets describe, however, are 

 not unalterable. Their major axes appear to be always the 

 same : but their eccentricities, the positions of their peri- 

 helion and nodes, together with the inclination of their 

 orbits to the ecliptic, seem to vary in a course of years. 

 These variations, being sensible only in a series of ages, are 

 called secular inequalities. There is no doubt of their ex- 

 istence : but the modern observations not being sufficiently 

 extensive, and the ancient not sufficiently exact, there stiil 

 rests some degree of uncertainty as to their magnitude. 

 The following table will show the inequalities that happen 

 in a period of one hundred years, and ar^ the values that 

 appear to accord best with the present observations. 



Secular iNEauALiTiEs of the Planets. 



The sign — signifies a Diminviion. 



Planets. 



Mercury 

 Venus . . 

 Earth . . . 

 Mars. . .. 

 Jupiter . , 

 Saturn . , 

 Uranus . 



In the 



Eccentricity. 



•000003867 

 -000062711 



-■oo( 041632 



•000090176 



000159350 



- ^0003 1 2402 



-000025072 



In the 



Perihelion. 



0" 1 SOI 10 



-0''OS2663 



00 364140 



0° 488405 



0" 20-1895 

 o" 597860 



0''0738U9 

 ~X4 



In the 

 Inclination. 



In the 



Place of Nodes 



0" 005612 

 -C^ 001405 



-0" 000447 



-O" 006g78 



-0" 004788 

 0" 000967 



—0* 241441 



— o» 57'j^g 



—0" 7 18665 



-o" 486904 

 — 0' 699525 



-I" 1 10481 j 



There 



