Chapter VI: The Planet Mars 180

The controversy about the habitableness of Mars. Humidity on
Mars. Early observations. The spectra of Mars and of the
Moon compared. Investigations by Campbell and Marchand. The
work of Lowell. Measurements by Slipher. Calculations by
Very. The temperature on Mars according to these sources.
Campbell’s expedition to Mount Whitney in California.
Oxygen on Mars. The cold on Mars detrimental to anything
but the lowest forms of life. Cause of different results
by Slipher and Campbell. Very’s answer to Campbell’s
criticism. New measurements by Slipher. Campbell’s new
method of measurement of 1910. Christiansen calculates
the temperature on Mars from intensity of the Sun’s
radiation. The sun-constant. Average temperature of Mars
about forty degrees Centigrade. Possibly low plant life
around the poles during summer. The canals on Mars are
probably fissures in the crust. The length of the canals
compared with that of the fissures in Earth’s crust.
The double canals on Mars compared with the parallel
fissures in Calabria. Emanations along the fissures. The
canals as affected by increasing cold or heat. The polar
snow. Thawing of the canals. Travel of the water vapour
independent of the topography. The desert sand on Mars.
Clouds and mists. Highlands and mountains on Mars. Sand
filling of the canals. The seas on Mars. The straightness
and uniform breadth of the canals an illusion. Light and
dark spots. “New” canals. The fancies of Lowell.