Refraction. There are times, mostly during westerly winds, when the river presents some strange examples of refraction. It is the general belief in Buenos Ayres when the coast of the Banda Oriental is seen from that city that a change of weather is at hand. This refraction is not always the same, as at times it permits one to see the tops of the hills of San Juan, which are some thirty-six miles off to the N N.E., whilst at other times the islands of the Paraná and the coast between Colonia and Martin Garcia are visible. During such weather it is difficult to make any nautical observations, and impossible to regulate any chronometer in the roads of Buenos Ayres. What has been stated concerning the winds, both outside and inside the Plate, must be considered as usual or general; but they may happen to the contrary, as they are so variable that no absolute rule can be set down as to either their point or duration, and the experience of successive years may be cutirely reversed some seasons. The Barometer. Although in the River Plate the rise and fall of the barometer are not very great, nevertheless its indications are almost always correct if consulted carefully. In settled weather its highest point is 760 milimetros, . and its general range is within 13m. to this in ordinary weather, but much more when severe changes occur. In the months of July and August the barometer is highest, and in that of June it is lowest. Its highest is during winds from S.E. to N.E., when it reaches even 778m. If the wind rounds to the N., the mercury will fall, and will continue so until N. W. blows. W. and S. W. winds produce the lowest barometer: thus it is that before ■ strong pampero the barometer will fall to 746 or 744, and even to 741, but ordinarily 746 is below the gradation of the River Plate. The rising of the glass when the wind is S. W. indicates that it is about to cease or -change to S. A high barometer, overcast sky, but red at sunset, threatening aspect, with distant lightning, a rising river and a strong curreut setting in, more especially above the Ortiz Bank, are all signs of a coming S. E. gale. From whatever point, a storm comes, or if the weather is murky, the barometer falls ;· but no sooner has it blown over, and the weather cleared, than it rises again. If it has set in for bad weather, the barometer remains low, until the wind be S.W., when a clearing pampero sets in: it is the same after some hours of great heat. lu Buenos Ayres the barometer falls with E. and S.E. winds, but soon rises if they die out, and will not again fall if the breeze does not spring up from the W., and then, if good weather, its change is but very little. If W. winds continue, and the barometer still falls, then it will blow again from the E. In general the barometer announces easterly winds by rising, though they may be fresh breezes, and westerly winds by falling; but storms or gales of wind, from whatever quarter, are always indicated by a fall. According to the observations of Fitzroy the river is low when the glass is steady, the gradation at such time being 29.9 English (or 758m.); and he never noticed it to be above 30.3 (769m.) or lower than 29.4 (745m.) Electricity. In summer, or indeed it might be said, during the whole year, thunderstorms are very frequent; so much so that perhaps the River Plate experiences more of them than any part of the world. They often cause damage to vessels, houses, and churches; but such accidents are not of such recurrence as one might expect from the vividness and rapidity of the lightning. Señor Azara states that during a N.W. storm on the 21st January, 1793, thirty-seven thunderbolts fell in the district around Buenos Ayres, killing nineteen persons. Temperature. It is of common experience to have in the one and same day a touch of the four seasons of the year, such is the extreme and rapid variation in the temperature. And though such sudden changes may affect the health, still it is certain that the climate of these parts of South America is excellent, never suffering from very extreme cold or warmth In Buenos Ayres the highest thermometer in summer is 30, and the lowest in winter 2 above zero, some rare instances having brought it down to zero: snow is also very seldom seen in these regions. The average temperature of Buenos Ayres is one or two grades higher than that of Montevideo, probably to be attributed to the proximity of the latter to the sea, and some other topographical differences. Tides. Captain Heywood says of the tides:-«The tides of the River Plate are far from being regular, the run of the current being so uncertain in velocity, duration, and direction. It is, therefore, impossible to base any calculations upon them, so that the lead has to be used for ascertaining both the soundings and the running. When it is calm weather the currents generally are not strong, and set in or out pretty regular. The currents always vary with the wind; thus, they run castward along the northern coast of the river when the wind is N.E., but set in, westward, strongly along the southern shore during a S.W. or pampero, the water rising amazingly both these currents produce the contrary effect on the opposite shores. The river is lowest during N.N.E. or N.N.W. winds, and at such times the currcot running out is on the south shore, but generally does not exceed three knots an hour; on the northern it is never very strong.» Ovarv::!, during a long cruise and many anchorings about Cape San Antonio and Sanborombon Bay, up to Cape St. Mary, gives it as his opinion that the tides at the mouth of the River Plate are generally regular, being only disturbed by heavy storms and high floods, so that the irregularity, caused by the wind, concerns more the inside. He states that in the anchorage of St. Clement the tide rises six feet, running N. W. for flood, and S.E. for cbb. At the Rodeo anchorage it rises six feet five inches, and ruus N. for flood and S. for the ebb. Off the tosca shores of Point Piedras it is high water full and change at 11h. 15m., rising six and a-half feet, and running N.N.E and S.S.W. In the port of Paloma (Cape St. Mary, the tides rise regularly five and a-half feet. At Maldonado, the highest rise during ordinary weather is six to seven feet, running S.E. for the flood and N.W. for ebbing. It should be remembered, nevertheless, that in all these ports if north winds continue long the rise is not so great, and, on the other band, if strong south winds set in there will be two feet more water, even exceeding that at times, outside winds always causing higher tides. Tides in Buenos Ayres. M. Thoyou, of the French navy, remarks that the tides at Buenos Ayres are more regular than might be supposed, and pretty accurately ascertained if the observation of the weather be attended to. He states that the flood sets in generally for five hours twenty-one minutes, and the cbb seven hours five minutes: high water full and change at 7h. 47m., ordinary rise tem feet eight inches. «Comparing observations,» says the same author, and taking into account the prevailing winds, which, undoubtedly have a influence, the irregularity of the tides is not so considerable as generally supposed. It will be seen, though the difference be not much, that with outside winds, such as N.E. to S.E., the flood will commence earlier than the calculated hour, succeeded by a proportionate longer ebb: and as ordinarily the flood is of shorter duration than the ebb, it is easy to deduce that the flood will set in earlier and be of longer duration during N.E. or S.E. wind, but it does not much affect the succession of tides. The flood makes in undisturbed during N.W. to S.W. winds, and the ebb is not affected if it does not blow strong from the S.W. As has been stated, the tides are pretty regular with ordinary winds from all quarters, but more so when the wind is E. or N., even when these blow fresh. The wind has more influence at high water, in checking the ebb, than during the flood; therefore when it blows from N.E. round to S.W., the water is dammed in longer, whilst the Paraná and Uruguay continue to discharge, so that the consequence is a much higher water and a later ebb. The reverse of this occurs with winds from N. to W. The difference in the rise of water at two consecutive tides is rarely more than three and a-half feet; but on some occasions, when the wind has been the same for several days, the difference has been known to be ten or cleven feet, and with N. and W. strong winds the difference has even been twenty feet-the water falling from thirty feet two inches to ten feet four inches. But these are very rare occasions, and it requires a combination of circumstances to produce them. As a rule, the rise and fall is not more than nineteen feet eight inches, and not less than six feet eight inches, giving ten feet eight inches as the average.» Low Tides. Very low tides are occasioned by strong winds from N.W. to S.W. In 1792 such a wind lasted three consecutive days, and the consequence was to leave the great River Plate nearly dry in most parts. During the Independence War an extraordinary event happened in this respect: the river was so low that the Spanish squadron anchored in the outer roads blockading Buenos Ayres were left aground, and the bank between the two roads appeared dry out of the water; the Argentines seeing this passed over some artillery to attack the squadron, and opened fire on a brigantine which was almost on her beam ends; but that moment the water began to rise, and they had to retire. So fast indeed did the flood flow in that, by the time the artillery got back to cross the inner roads, only the horses' heads appeared above water. Señor Azara remarks :-The River Plate may be considered a gulf of the sea, though it preserves the freshness of its water twenty-five or thirty leagues below Buenos Ayres. The strong tides of the southern coast do not prevail here, and the water does not rise or fall according to the floods in the river, but is mostly affected by the winds, thus E. or S.E. wind will cause an additional rise of seven feet. General Movement of Waters. In regard to this M. Duperier remarks :—«Two causes affect the movement of the waters of the River Plate; one is the proportionate strength and duration of local winds, the other, it is not certain, but presumed, is attributable to the prevailing winds, whether along the north shore or from the south at the mouth of the river. Easterly winds, and the adjacent points, will always cause the water to rise along the whole river; northerly winds produce low water in the left channel, and high water in the right channel. Winds from W. to S.W. will cause the water to fall in the whole river, as far as the Ortiz Bank, except in a part near Colonia, where the water rises in the left channel. It is true that the extent of this rise or fall will depend much on the force of the wind, but the pressure of such a mighty body of water is sufficient to move the current from one channel to the other. Respecting the rise and fall which are without any apparent local cause, it may be said they are common to the whole river. Though these effects are well known, it is not easy to ascertain their immediate cause; if observations were taken at the one and same time at several points of the river-say Montevideo, Colonia, Martin Garcia, Buenos Ayres, and the south extremity of the Ortiz Bank or Point Indio-it might be possible to arrive at some solution of this phenomena, especially if added to the experience of many years.» As yet, however, the pilots of the river are content with knowing by experience that always when fresh northerly winds blow, or N.W., even also N.E., the river falls considerably, and the current runs to the S E. and S.; and when pamperos or S.E. winds prevail, then the river rises, and the waters run S.W., or N.W., according to the channel. But there are occasions when, without wind or any visible cause, the river rises and falls considerably. It may be these are owing to high tides out at sea, or perhaps to floods in the two great affluents, the Paraná aud Uruguay; if the latter, then fresh water ought to flow in the |