he
corroborative evidence of other observers, for, after years of
experiment, Professor Lowell and his staff have succeeded in taking
direct photographs of Mars, which show several of the disputed lines.
One would have thought that would settle the question, but, although
some of the more reasonable of the objectors have been convinced by the
evidence of the photographs, many others still maintain their attitude
of scepticism, especially those who have not themselves seen the
photographs. They declare it to be quite impossible for any such
photographs to be taken, because our atmosphere would prevent any
photographic definition of fine detail on such small pictures; yet about
ten thousand of these tiny photographs were taken during the near
approach of Mars in 1907.

"As I possess a number of these photographs I can testify that they do
show some of the lines, and persons who disbelieved have expressed
surprise at their excellence. Success was only obtained by means of
specially sensitised plates, for the ordinary photographic rays and
ordinary plates were found useless, whilst the process of photographing
so small and distant a planet is surrounded with difficulties.

"Even when attached to a telescope giving an equivalent focal length of
nearly 150 feet, the camera only gives a very tiny image of the planet.
The lighting of the small image is faint, but if additional power were
used on the telescope to obtain a larger image, then its light must be
still fainter, and thus a longer exposure would be required to obtain a
picture on the plate. As Mars moves in its orbit and rotates on its
axis, and our atmosphere is subject to continual movement and
disturbance, any long exposure would result in a blurred picture, which
would show no fine detail. So, as a short exposure is essential, only a
small picture can be taken. Nothing is gained by any subsequent great
enlargement of the picture, because the grain of the film of a quick
plate is coarse; and, if enlarged, this also blurs out the detail.

"Having regard to all the difficulties which had to be surmounted, it
was a great and undoubted triumph to secure detail on such tiny
photographs of this distant world. As time goes on improvements will
probably be effected and still better pictures secured; but enough has
now been accomplished to prove that the lines cannot be illusions, but
really exist upon the planet. If the eye can be deceived in this
respect, the camera can