the blood by the inspired oxygen. The Captain soon saw this, by noticing
with what difficulty Diana was panting. She even appeared to be
smothering, for the carbonic acid--as in the famous _Grotto del Cane_ on
the banks of Lake Agnano, near Naples--was collecting like water on the
floor of the Projectile, on account of its great specific gravity. It
already threatened the poor dog's life, though not yet endangering that
of her masters. The Captain, seeing this state of things, hastily laid
on the floor one or two cups containing caustic potash and water, and
stirred the mixture gently: this substance, having a powerful affinity
for carbonic acid, greedily absorbed it, and after a few moments the air
was completely purified.

The others had begun by this time to check off the state of the
instruments. The thermometer and the barometer were all right, except
one self-recorder of which the glass had got broken. An excellent
aneroid barometer, taken safe and sound out of its wadded box, was
carefully hung on a hook in the wall. It marked not only the pressure of
the air in the Projectile, but also the quantity of the watery vapor
that it contained. The needle, oscillating a little beyond thirty,
pointed pretty steadily at "_Fair_."

The mariner's compasses were also found to be quite free from injury. It
is, of course, hardly necessary to say that the needles pointed in no
particular direction, the magnetic pole of the Earth being unable at
such a distance to exercise any appreciable influence on them. But when
brought to the Moon, it was expected that these compasses, once more
subjected to the influence of the current, would attest certain
phenomena. In any case, it would be interesting to verify if the Earth
and her satellite were similarly affected by the magnetic forces.