r, but the terrestrial
atmosphere singularly lessened its optical power. Thus Barbicane, in his
projectile, by looking through his glass, could already perceive certain
details almost imperceptible to observers on the earth.

"My friends," then said the president in a grave voice, "I do not know
where we are going, nor whether we shall ever see the terrestrial globe
again. Nevertheless, let us do our work as if one day it would be of use
to our fellow-creatures. Let us keep our minds free from all
preoccupation. We are astronomers. This bullet is the Cambridge
Observatory transported into space. Let us make our observations."

That said, the work was begun with extreme precision, and it faithfully
reproduced the different aspects of the moon at the variable distances
which the projectile reached in relation to that orb.

Whilst the bullet was at the altitude of the 10th north parallel it
seemed to follow the 20th degree of east longitude.

Here may be placed an important remark on the subject of the map which
they used for their observations. In the selenographic maps, where, on
account of the reversal of objects by the telescope, the south is at the
top and the north at the bottom, it seems natural that the east should
be on the left and the west on the right. However, it is not so. If the
map were turned upside down, and showed the moon as she appears, the
east would be left and the west right, the inverse of the terrestrial
maps. The reason of this anomaly is the following:--Observers situated
in the northern hemisphere--in Europe, for example--perceive the moon in
the south from them. When they look at her they turn their backs to the
north, the opposite position they take when looking at a terrestrial
map. Their backs being turned to the north, they have the east to the
left and the west to the right. For observers in the southern
hemisphere--in Patagonia, for example--the west of the moon would be on
their left and the east on their right, for the south would be behind
them.

Such is the reason for the apparent reversal of these two cardinal
points, and this must be remembered whilst following the observations of
President Barbicane.

Helped by the _Mappa Selenographica_ of Boeer and Moedler, the
travellers could, without hesitating, survey that portion of the disc in
the field of their telescopes.

"What are we looking at now?" asked Michel.

"At the northern portion of the Sea of Clouds," answered Barbi