tion occurs under the most favourable
circumstances every fifteen years. There was one in 1862, another
in 1877, one in 1892, and so on.

When Mars is 35 million miles off and we apply a telescope
magnifying 1,000 diameters, we see him as if placed 35,000 miles
off. This would be seven times nearer than we see the moon with
the naked eye. As Mars has a diameter about twice as great as
that of the moon, at such a distance he would look fourteen times
the diameter of the moon. Granting favourable conditions of
atmosphere much should be seen.

But these are just the conditions of atmosphere of which most of
the European observatories cannot boast. It is to the honour of
Schiaparelli, of Milan, that under comparatively unfavourable
conditions and with a small instrument, he so far outstripped his
contemporaries in the observation of the features of Mars that
those contemporaries received much of his early discoveries with
scepticism. Light and dark outlines and patches on the planet's
surface had indeed been mapped by others, and even a couple of
the canals sighted; but at the opposition of 1877 Schiaparelli
first mapped any considerable

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number of the celebrated "canals" and showed that these
constituted an extraordinary and characteristic feature of the
planet's geography. He called them "canali," meaning thereby
"channels." It is remarkable indeed that a mistranslation appears
really responsible for the initiation of the idea that these
features are canals.

In 1882 Schiaparelli startled the astronomical world by declaring
that he saw some of the canals double--that is appearing as two
parallel lines. As these lines span the planet's surface for
distances of many thousands of miles the announcement naturally
gave rise to much surprise and, as I have said, to much
scepticism. But he resolutely stuck to his statement. Here is his
map of 1882. It is sufficiently startling.

In 1892 he drew a new map. It adds a little to the former map,
but the doubling was not so well seen. It is just the strangest
feature about this doubling that at times it is conspicuous, at
times invisible. A line which is distinctly seen as a single line
at one time, a few weeks later will appear distinctly to consist
of two parallel lines; like railway tracks, but tracks perhaps
200 miles apart and up to 3,000 or even 4,000 miles in length.

Many speculations were, of course, made to account for the origin
of such features. No known s