420 SIR JAMES SOUTH ON THE EXTENSIVE ATMOSPHERE OF MARS. 
The phenomena were also witnessed by Mr. Henry South, and his obser- 
vations strictly accorded with my own. To render our results as independent 
as possible of optical misrepresentation, his instrument was my Gregorian 
reflector, by Watson, of six inches aperture and thirty inches focus ; the figure 
of its metal was exquisitely perfect, whilst twelve years of constant use, had 
not occasioned the slightest tarnish of its almost colourless surface. 
Accustomed as the first business of the night, to point a telescope to such of 
the principal planets as are above the horizon, on the 17th of March of the 
present year I had the satisfaction of seeing in the field of the 5-feet Equa- 
torial, with the planet Mars, several stars, some of them minute, but one of the 
5th and another of the 6th magnitude. Convinced that the planet would 
pass close by, or perhay occult the larger, I took its place, and found it to be 
3 7 Tauri. The covering under which the dome for my large equatorial was 
being built, unfortunately rendered the 5-feet equatorial useless, when the 
planet had approached within forty seconds of the star. The observations 
therefore were continued with the 12-feet Achromatic of 7| inches aperture, 
and' also with the 42-inch of 2f aperture, till the star was one diameter 
and a half of the planet from his nearest limb ; when, fearing lest the trees 
to the north-west of my grounds, might intercept the planet from my view, 
at the instant of nearest appulse or occultation, the 8-feet Achromatic of 
six inches aperture previously placed on the top of the house, was recurred 
to. The star, from being a full diameter distant from the planet when 
first observed with this telescope, was watched most unremittingly till the 
planet, having been in contact with it, had receded from it a quantity equal 
to its own semi-diameter. The star suffered not the least change of colour, 
nor the least diminution of its lustre, except what of the latter might fairly 
be attributed to the splendour of the planet ; its rays were certainly in con- 
tact with the planet’s limb, but only at their circumference ; at times the 
planet and star were very steady, at other times far otherwise ; but at no 
period was there such contrast between the steadiness of the star and the un- 
steadiness of the planet, as occurred at the occultation of 42 Leonis. As the 
star’s distance from the planet diminished, the former seemed to undergo not 
the slightest alteration ; and when in actual contact, both the star and the 
planet were red, but the planet had the deeper tint. The night was remark- 
