gin
--Very's researches on the moon's temperature
--Application of these results to the case of Mars
--Cause of great difference of temperatures of earth
and moon
--Special features of Mars influencing its
temperature
--Further criticism of Mr. Lowell's article
--Very low temperature of arctic regions on Mars.

CHAPTER VII.

A SUGGESTION AS TO THE 'CANALS' OF MARS,
--Special features of the canals
--Mr. Pickering's suggested explanation
--The meteoritic hypotheses of origin of planets
--Probable mode of origin of Mars
--Structural straight lines on the earth
--Probable origin of the surface-features of Mars
--Symmetry of basaltic columns
--How this applies to Mars
--Suggested explanation of the oases
--Probable function of the great fissures
--Suggested origin of blue patches adjacent to snow-caps
--The double canals
--Concluding remarks on the canals.

CHAPTER VIII.

PAGE SUMMARY AND CONCLUSION,
--The canals the origin of Mr. Lowell's theory
--Best explained as natural features
--Evaporation difficulty not met by Mr. Lowell
--How did Martians live without the canals
--Radiation due to scanty atmosphere not taken account
of
--Three independent proofs of low temperature and
uninhabitability of Mars
--Conclusion.

CHAPTER I.

EARLY OBSERVERS OF MARS.

Few persons except astronomers fully realise that of all the planets of
the Solar system the only one whose solid surface has been seen with
certainty is Mars; and, very fortunately, that is also the only one
which is sufficiently near to us for the physical features of the
surface to be determined with any accuracy, even if we could see it in
the other planets. Of Venus we probably see only the upper surface of
its cloudy atmosphere.[1] As regards Jupiter and Saturn this is still
more certain, since their low density will only permit of a
comparatively small proportion of their huge bulk being solid. Their
belts are but the cloud-strata of their upper atmosphere, perhaps
thousands of miles above their solid surfaces, and a somewhat similar
condition seems to prevail in the far more remote planets Uranus and
Neptune. It has thus happened, that, although as telescopic objects of
interest and beauty, the marvellous rings of Saturn, the belts and
ever-changing aspects of the satellites of Jupiter, and the moon-like
phases of Venus, together with its extreme brilliancy, still remain
unsurpassed, yet the greater amount of details of these feat