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POPULAR SCIENCE REVIEW. 
has derived the following approximate circular elements of the orbits. The 
probable errors assigned are only very rough estimates : — 
The Outer Satellite. 
Major semi-axis of apparent orbit, at distance [9*5930] 
Minor . < „ . • 
Major semi-axis of orbit at distance unity 
Position angles of apsides of apparent orbit 
Passage through the west apsis (p — 250°) 
Period of revolution 
Hourly motion in areocentric longitude . 
Inclination of true orbit to the ecliptic 
Longitude of ascending node 
82"-5 + 0"-5 
27"-7 + 2" 
32"-3 
70°, 250° (±2°) 
Aug. 19, 16h.6, 
. W.M.T. 
30 h. 14m. + 2m. 
ll°-907 
25°-4 + 2° 
82° -8 + 3° 
Position of pole of orbit on celestial sphere : 
long. 352°-8 R.A. 316-1 
lat. +64-6 Dec. +53 8 
These elements give for the mass of Mars, one 3,090,000th of sun’s. 
The Inner Satellite. 
Major semi-axis of apparent orbit, dist. [9-5930] 
Period of revolution 
Hourly motion in areocentric longitude . 
Passage through the eastern apsis (p = 70°) 
33 // -0 ± l" 
7 h. 38-5 m. + 0-5 m. 
47°*11. 
Aug. 20, 13h.W.M.T. 
It will be found, on comparing the position of the pole of orbit of the outer 
satellite with that of the pole of the Martian equator, as indicated in our paper 
on Mars in the July number, that the plane of motion of the outer satellite 
lies very near the plane of the Martian equator. Indeed, when we consider 
the nature of the observations by which the positions of both planes have 
been determined, we may fairly say that within the probable limits of error of 
observation these two planes are identical. From the elements given in the 
article on Mars, it will be seen that the R.A. of the pole of the Martian 
equator is assumed there to be 312° 4', the north declination 50°T8', accord- 
ing to which the two poles would be distant about 4° in R. A. and about 3^° 
in declination. The construction given in the above-named article will 
become strictly correct for the satellite orbit, in this or any future year 
(subject always to any change which may have to be made in the estimated 
elements, if, for N, 43°*9 be substituted, and for I (misprinted No. 1 in the 
article) 36°-2. As it is, the ellipse e'e represents with considerable correct- 
ness the nearer half of the orbit for the opposition of the present year. 
The mass of Mars may be regarded as more correctly determined from the 
observations of the outer satellite during a few days, than from a century of 
observations and a mass of laborious computations on which Leverrier’s 
masterly determination of the mass had been based. Since Leverrier deter- 
mined the mass of Mars at one-2, 968,300th of the sun’s, it follows that the 
mass has been diminished by the difference between one-3, 000, 000th and 
