INDOCHINA
768
INDO-CHINA
low and intersected by the numerous embouchures of
the Me-kong, to the alluvial deposits of which this fer-
tile section of Indo-China owes its existence. From
Ha-tien to the conventional Siamese frontier cliffs and
sandy plains again alternate. The Me-kong, the
great river to which Indo-China owes so much of its
fertility and territory, rises in the central plateau of
Asia and on entering the peninsula is already a miglity
river. Owing to its numerous rapids, the river can be
used for purposes of navigation only on restricted
stretches, until below the Rapids ofKhone. Even
later there arc some minor rapids which are not, how-
ever, an insurmountable obstacle to traffic. From
Pnom-penh, where the river divides into two branches,
the navigation is easy. These branches — known
to the French colonists as the Fleuve antcrieur and
the Fleuve posUrieur — subdivide in turn, and form
the network of streams which are the chief means of
communication between the various commercial
centres of Cochin China and Cambodia. Other rivers
of importance will be referred to later in treating of the
separate political division.
Climate and Hygienic Conditions. — Although the climate of Indo-China is, in general, like that of other intertropical countries, characterized by great heat and dampness, there exists a great difference in the climatic conditions of the various districts. In Cochin China the wet and dry seasons succeed each other with the utmost regularity, and correspond with the mon- soons. The period of the north-easterly monsoon, which blows from October to April, is the dry season, during which the thermometer registers between 78.8° and 80.0° liy day and C8° by night. About the mid- dle of April the monsoon changes to the south-west, the temperature rises to 98°, and the season of daily rain begins. The climate of Cambodia resembles in general that of ("ochin China, except that, deprived in the north of the sea breezes, the heat is much more rigorous. In Annam the climate is less regular. The heavy rains do not coincide with the south-west mon- soon, which is interceptetl by the Annamite Range, but fall usually during the season of the north-east. In Hue they begin in September and last until December, the temperature falling below 60°, and so consistent and heavy is the downpour that it is often impossible to leave the house for several successive days. The other seasons are b.y no means rainless ; there is, how- ever, no regularity in the intervals between the show- ers, which are very heavy but last only a few hours. Tong-king has two clearly defined seasons correspond- ing with the monsoons: a winter from October to April, and a summer iluring the remaining period of the year. April and October are themselves months of transition, and resemble somewhat our spring and autumn. During the winter the temperature is com- paratively low, the thermometer falls to 42° or 40°, and instances of white frost have been recorded. During this season the wind blows from the north- east, but, when it chances to veer to the south, the thermometer rises suddenly 12, 15, or even 20 degrees. The weather is most changeable, being now bright and clear and now foggy and rainy. Heavy rains are, however, rare, and the length of the winter allows one to recuperate one's strength after the exhausting sum- mer. A fine rain falls almost unceasingly from Janu- ary to April. In the latter month the wind changes to the south-east, and the temperature rises to 75°. In July and .\ugust, the hottest months, the tempera- ture varies between 80° and 86°, although not infre- quently the thermometer rises to 95°, 100°, and even 104°, and remains there for days. As the w'ind usu- ally falls away at sunset, the nights are often as hot as the days. During the summer the rains are rare, and usually very heavy and accompanied by violent storms. The heaviest showers fall between May and August, and a rainfall of four inches within twenty- four hours has been recorded in the latter month.
Between the climatic conditions of Northern and
Southern Laos there is a marked difference. In general
there are two clearly defined seasons: the dry from
October to March, with very occasional rain-storms,
and the wet from April to October, during which period
there are abundant and almost daily rains. In North-
ern Laos the temperature during the former season is
relatively low — 43° (even lower in the more elevated
districts) in December and January. During the sum-
mer, especially in .\pril and May, the heat is over-
whelming: the thermometer often rises to 100° and
104°, and there is little difference between the day and
the night readings. The climate of Southern Laos is
much more tolerable, and is free from the rapid varia-
tions of temperature common in the north. The
northern territories of Indo-China, particularly Tong-
king, are frequently visited by typhoons, the southern
sections very rarely. Two kinds are distinguislu^d:
(I) the continental cj-clones, which originate in Siberia
and Eastern China and advance towards the sea; (2)
the typhoons which originate in the Pacific Ocean.
Though fre<iuent during both seasons, the typhoons
are much more violent in winter. When the barome-
ter falls to 28.5°, a typhoon may be confidently pre-
dicted. Notwithstanding the terrific rapidity of its
rotary motion, the typhoon advances with compara-
tive slowness, and warning is usually received by
telegraph from the observatories along the southern
coast of China in ample time to permit shipping and
inhabitants to seek shelter before its approach. The
typhoons of 1851 and 1882, when the sea invaded the
southern coasts of Tong-king, are the most violent re-
corded. Father Legrand de la Lyraie relates that
10,000 perished in 1851 in consequence of the inroads
of the sea. In 1882, the sea rose twenty-seven feet
above its ordinary level at high tide, and 40,620
corpses were recovered, 205 having entirely disap-
peared.
The climate of Indo-China is very unhealthy for Europeans, who can never liecome acclimatized. As a rule the mountainous and wooded regions are the most insalubrious — a phenomenon attributable partly to the vast accumulation of animal and vegetable detritus in the dense br\ishwood undisturbed for cen- turies, and partly to the dampness caused by the noc- turnal mists and the excessive density of the vegeta- tion. Here intermittent fevers (e. g. the terrible wood- fever) and dysentery menace the inhaliitants at every season, antl sjiare neither colonist nor native. Rca.sonable exi)loita(ion of the timber, for which how- ever proper modes of conveyance are still wanting, or the clearing away of sections of the vast forests which cover the land, should have a beneficial effect on the hygienic conditions of these regions. The low, culti- vated plains are the least unhealthy, for, though even here intermittent fevers are by no means rare, they have not the severity one witnesses in other localities. In no district can the European escape dysentery and ana?mia, but, by avoiding heavy exercise and every excess and by guarding against the extreme heat of the day and the dampness of the night, he can evade all the more serious attacks of the maladies. Periodi- cal sojourns in less rigorous countries to recuperate his strength are of course indispensable. The maritime districts are the mo.st tolerable for Europeans: the regular breezes from the sea counteract to a great ex- tent the injurious effects of the climate, and facilitate sleep. The winter in Tong-king, which necessitates warmer clothing and even the artificial heating of the houses, allows the settler to recover his strength after the exhausting summer. The hot season is, however, terrible, and intermittent fevers, affections of the liver, and cholera make great ravages among the French troops. To engage in industrial or agricultural labour is always fatal for Europeans. Thanks to its favourable situation along the coast the summer heat in Annam is less extreme, and the maladies are neither
