352 The Naturalist Brazilian Expedition. [April, 
more northerly of these is. called Zagoa dos Patos (Lake of the 
Ducks); the Lagoa-mirim (Smaller Lake) empties into this through 
the River Sao Gongalo. Between the lakes and the ocean the 
dunes form two long peninsulas, varying in width from fiveto 
twenty miles. These peninsulas are entirely composed of sand, 
the drifted masses varied only with mangrove swamps and brack- 
ish or fresh-water lakes. They are perfectly barren, and almost 
without inhabitants. : 
The Rio Grande is the only passage through this sand-wall, 
and with some trifling exceptions the only outlet of the rich and 
populous province of Rio Grande do Sul. It is a shallow chan- , 
nel, twelve or fourteen miles long, half a mile wide at the oceat 
end, and gradually broadening towards the lakes. Unfortunately 
a very dangerous sand-bar has been formed before the mouth 
which is yearly growing worse, and of late has caused serious 
apprehensions for commerce. In its formation this bar is aw ‘ 
gether different from the shallows commonly found at the mouths 
of rivers. It has been built up, in great part, by the ocean currents 
and the north and north-west winds. The winds take up great | 
clouds of sand from the dunes, scattering them broadcast before 
the channel; the currents sweeping south-westward along the ens i 
catch up the sands as they fall, piling them in great banks e 
the shallows. The slight outflow from the Rio Grande sea 4 i“ 
keep the detritus from accumulating directly in its mouth, ane" i 
bar forms a great semicircle around it. The Rio Gra pe 
brings very little sand or mud to the sea; I question, \"" 
whether the tides are not washing the sea-coast sands throug 3 
channel into the lakes, vue 
The condition of the bar varies greatly, more with the 
than with the tides; a long-continued south or south-west 
piles up the water, but even at the most favorable times ae 
is seldom more than ten or eleven feet, and with a north g a 
banks are almost dry. With a gale or even a strong eas 
the bar becomes impassable on account of the surf; witha 
it is apt to shallow rapidly. Worst feature of all, these that 
take place very suddenly and at irregular intervals, 50 © Grande 
bar is the very emblem of fickleness among the Re 
sailors. Old residents say that during the early yas è tl 
„century the bar was even worse than it now is; 200% so 
was broken by a heavy storm, and after that, for forty? x 
