39 
THE PLANET MARS IN FEBRUARY 1869. 
By RICHARD A. PROCTOR, B.A., F.R.A.S. 
ArxHOE OF Sattjkn atstd its System,” “ Half-hours with the 
Telescope,” &c. &c. 
T the last opposition of Mars, I had the opportunity of dis- 
cussing in these pages some of the phenomena presented 
by this interesting planet. In my paper on the subject,* I 
dealt with certain points which, as it appeared to me, should 
have found a place in our popular treatises of astronomy. The 
effects of the eccentricity of the planet’s orbit, the nature and 
epochs of the seasonal changes which take place upon his sur- 
face, these and other such points seemed to require a closer 
attention than they had received in the ordinary books of 
astronomy. For instance, I believe that the diagram of the 
orbits of the earth and Mars which accompanied that article 
was the first in which the true relations of these orbits have 
been exhibited on an exact scale. Yet the effect of the relations 
thus presented is one of the most striking in the economy of 
the solar system. It had been discussed, in general terms, 
again and again, yet no one had been at the pains to illustrate 
it — in other words, to present it in that form which alone has 
any real significance to nine out of ten of those who read trea- 
tises on popular science. 
Having thus, in that paper, examined what I hold to be the 
fundamental relations of the planet Mars, I now feel freer to 
discuss other questions — considerations connected with the phy- 
sical habitudes of the planet, its fitness to be the abode of living 
creatures, and other such points. I would, however, refer those 
who wish to know how the planet and the earth will be situated 
at the approaching opposition, to the paper here referred to. 
The line marked 1869 in the plate of diagrams accompanying 
that article indicates the direction in which the two planets are 
situated as respects the sun, on February 13, the day of oppo- 
* Popular Sciexce Review, No. 22, for January 1867. 
