466 The Planet Mars. 



possibly, to the existence of Thallium in the meteoric bodies ; 

 as is also the existence of strong lavender light in some of the 

 blue- coloured meteor- streaks occasionally without any con- 

 tinuous spectrum. The morning of the 14th of November next 

 will present an opportunity for verifying the. striking variety 

 of colour so unexpectedly revealed by the spectroscope in the 

 light ; and hence also, probably, a corresponding diversity in 

 the chemical composition of the November meteors. 



Mr. Browning adds : — 



" On account of the great difficulty which attends these 

 observations, I cannot be at all positive of the accuracy of 

 these results, except in the case of those which I have called 

 the first class of meteor-spectra (i. e., uniform continuous 

 spectra of the nuclei) . 



" At about a quarter to two, a large meteor, of a greenish- 

 yellow colour, shot from near Hegulus through the belt of 

 Orion. This meteor left a train of a steel-gray colour, which 

 was visible for nearly three minutes, although the end of its 

 path was partially obscured by fleecy clouds." 



THE PLANET MAES. 



BY RICHARD A. PROCTOR, B.A., E.R.A.S. 



My object in the present paper is to exhibit to the readers of 

 the Intellectual Observer the true relations under which the 

 planet Mars will present himself at the opposition which takes 

 place during January, 1867. 



There is a marked variation in the circumstances under 

 which Mars is seen at successive oppositions. The other 

 superior planets vary chiefly as respects the altitude at which 

 they cross the meridian (or culminate) while in or near oppo- 

 sition. Mars partakes of these changes* — in fact we shall pre- 

 sently see that they are exhibited in a somewhat exaggerated 

 form in his case; but there are other and more marked 



* A superior planet corning to opposition in midwinter attains an altitude 



about equal to the sun's midsummer altitude ; near the equinoxes a planet in 



opposition has a mean altitude about equal to the sun's altitude at either equin x ; 



and, lastly, a planet coming to opposition in midsummer attains an altitude only 



equalling the sun's altitude in midwinter. The reason i9 obvious — for the sun is 



always o.i the ecliptic, while the planets all travel near the ecliptic, and the 



ecliptic must be high by night when it is low by day, and vice versa. These 



is produce a variation of 47° in (lie meridian altitude of a planet, a range 



Lange which is yet further increased owing to the inclination of the 



bits to the ecliptic. The effect due to the last cause is small, however, 



t in the case of Mars. 



