On a second night we witnessed a splendid scene of natural fireworks; the mast-head and yard-arm-ends shone with St.Elmo's light; and the form of the vane could almost be traced, as if it had been rubbed with phosphorus.

The sea was so highly luminous, that the tracks of the penguins were marked by a fiery wake, and the darkness of the sky was momentarily illuminated by the most vivid lightning.
When within the mouth of the river, I was interested by observing how slowly the waters of the sea and river mixed.

The latter, muddy and discoloured, from its less specific gravity, floated on the surface of the salt water.

This was curiously exhibited in the wake of the vessel, where a line of blue water was seen mingling in little eddies with the adjoining fluid.
JULY 26, 1832.
We anchored at Monte Video.

The "Beagle" was employed in surveying the extreme southern and eastern coasts of America, south of the Plata, during the two succeeding years.