In examining Mr. Dawes’ drawings it was necessary that the position of Mars’ axis should be known.  The data for determining this were taken from Dr. Oudemann’s determinations given in a valuable paper on Mars issued from Mr. Bishop’s observatory.  But instead of calculating Mars’ presentation by the formulae there given, I found it convenient rather to make use of geometrical constructions applied to my ’Charts of the Terrestrial Planets.’  Taking Maedler’s start-point for Martial longitudes, that is the longitude-line passing near Dawes’ forked bay, I found that my results agreed pretty fairly with those in Prof.  Phillips’ map, so far as the latter went; but there are many details in my charts not found in Prof.  Phillips’ nor in Maedler’s earlier charts.

I have applied to the different features the names of those observers who have studied the physical peculiarities presented by Mars.  Mr. Dawes’ name naturally occurs more frequently than others.  Indeed, if I had followed the rule of giving to each feature the name of its discoverer, Mr. Dawes’ name would have occurred much more frequently than it actually does.

On account of the eccentricity of his orbit, Mars is seen much better in some oppositions than in others.  When best seen the southern hemisphere is brought more into view than the northern because the summer of his northern hemisphere occurs when he is nearly in aphelion (as is the case with the Earth by the way).

The relative dimensions and presentation of Mars, as seen in opposition in perihelion, and in opposition in aphelion, are shown in the two rows of figures.

In and near quadrature Mars is perceptibly gibbous.  He is seen thus about two months before or after opposition.  In the former case, he rises late and comes to the meridian six hours or so after midnight.  In the latter case, he is well seen in the evening, coming to the meridian at six.  His appearance and relative dimensions as he passes from opposition to quadrature are shown in the last three figures of the upper row.

Mars’ polar caps may be seen with very moderate powers.

I add four sets of meridians (Plate 6), by filling in which from the charts the observer may obtain any number of views of the planet as it appears at different times.

Passing over the asteroids, which are not very interesting objects to the amateur telescopist, we come to Jupiter, the giant of the solar system, surpassing our Earth more than 1400 times in volume, and overweighing all the planets taken together twice over.

Jupiter is one of the easiest of all objects of telescopic observation.  No one can mistake this orb when it shines on a dark sky, and only Venus can be mistaken for it when seen as a morning or evening star.  Sometimes both are seen together on the twilight sky, and then Venus is generally the brighter.  Seen, however, at her brightest and at her greatest elongation from the sun, her splendour scarcely exceeds that with which Jupiter shines when high above the southern horizon at midnight.