lev. 2,290 ft.). Barring a slight undulation in
the land to the north-east of the marsh, the country was there absolutely
flat.

At night I witnessed a marvellous lunar effect. The half-moon was high up
in the sky. Soon after sunset two immense concentric arches of mist, with
their centres on the horizon to the east, shone like silver rings, their
upper edges being lighted by the bluish light of the moon. With the
reflection of this in the still waters of the lagoon, the effect was
enchanting and intensely picturesque.

My men suffered a great deal from the damp--they were always suffering
from everything: from the heat of the sun, the rain, the cold, the long
marches.

That night we had a minimum temperature of 51 deg. Fahr., the elevation of
our camp being 2,150 ft.

Naturally, over the expanse of water the sunrise was wonderful. The sky
was well covered by feathery radiations from the north-east, which were
intersected by striations shooting skyward from east to west and forming
a charming design. The radiations from the north-east reached right
across the sky as far as the horizon to the south-west. What astonished
me most in Matto Grosso was the characteristic immobility of the clouds.
In the day-time they remained sometimes for hours with hardly any changes
or movement. As soon as the sun appeared, rendering the lower sky of a
golden yellow and of vivid Indian red above, the northern part of the
lagoon was enveloped in mist, which rose in angular blocks, vertical on
the south side, slanting at a sharp angle on the north. These pointed
peaks of mist remained immobile--as if they had been solid--until the sun
was well up in the sky.

I went once more to gaze at the glorious panorama. In the morning light
new and important details were revealed, such as a strange series of
dykes of a prismatic shape, of which I could count as many as seven.
Great transverse depressions or grooves--from S.S.E. to N.N.W., with a
dip S.S.E.--could in that light be now plainly detected, and this time
two great square castles of rock--instead of one--were disclosed upon the
third range of undulations.

The high ridge to the south-west displayed a subsidence on a large scale
in its central portion, where bare vertical red walls had been left
standing on each side.

Then there were other curious concave depressions or gateways formed in
the great table-land--which had for its marked characteristic concave
curves on all its slopes.