areful and continuous
observation. Sir William Herschel suggested that the red colour was
attributable to the vegetation of Mars being red, instead of green as on
our earth; but it was generally considered that the red areas indicated
land and the dark areas water. The work of our modern observers has,
however, resulted in a general revision of our ideas on these points.

"It had long been reasoned that, as the earth was accompanied by a
moon, and Jupiter had at least four, Mars, the intermediate planet,
might be expected to possess a satellite. The planet itself being small,
its moon would probably be very small, and likely to be overlooked when
observing with the telescope, because its light would be overpowered by
the light of the planet, which would make the telescopic field of view
very bright. Up to the year 1877 the most powerful instruments had been
used without success in the search for the supposed satellite.

"In that year Mars made an exceptionally near approach to the earth, and
Professor Asaph Hall, of Washington Observatory, took up the search,
using a splendid refracting telescope having an object-glass 26 inches
in diameter. The methods he adopted were rewarded with success, for he
discovered not only one, but two satellites of Mars, and they were given
the names of Phobos and Deimos.

"Both these satellites are very close to the planet and extremely small,
Phobos being less than 4000 miles from the planet's surface, and Deimos
only 12,300 miles from it. As seen in the telescope, they are very faint
points of light which cannot be measured by ordinary means, and the
estimation of their size was a matter of great difficulty.

"Professor Langley gives an interesting account of the endeavour to
estimate their size by the amount of light reflected, as compared with
the light afforded by our own moon when full. It was a most difficult
task, as the comparison had to be made by means of tiny holes drilled in
metal plates; and for a long time it was impossible to find a workman
who could drill a hole sufficiently small for the purpose, although one
of those employed had succeeded in drilling a hole through a lady's thin
cambric needle from end to end, thus converting it into a tiny steel
tube. One would have thought such a feat impossible; yet what was now
required was a hole smaller than the one thus made through the tiny
needle."

"My word!" said M'Allister, "I would like to see the mon who did that
pi