The Geographical Journal (Journal of the Royal Geographical Society): Volume X, No. 6 [‎121v] (95/186)

G34
THE MONTHLY RECORD.
of Italy, might, he thinks, have been introduced by winds and currents; and as
for the Yalonia oak (Quercus cegilops), which occurs here and there in Apulia, but
nowhere else in Italy, that might have been planted by man on account of its-
valuable acorn-cups.
The Rainfall of Western Europe— In the first part of the newly issued'
volume of the Annales du Burtau central Meteorologiqiie de France (Annee, 1895
Paris, 1897), Dr. Alfred Angot publishes a paper on this subject, which supplements
that on the rainfall of the Iberian peninsula, which appeared in 1895. In both Dr.
Angot calculated the mean annual and monthly rainfall for the thirty years 1861-90,
and reduced the returns from stations which were not active during the whole period to
the thirty years’ means, by means of interpolations. In this way comparable results
have been obtained, a matter of great importance in the case of rainfall which varies
greatly from year to year, and we may regard this paper as the most important
contribution to the climatology of Central, Western, and Southern Europe that has
appeared since Dr. Hann’s classical discussion of the mean pressure for the same
region, also studied on a thirty-years mean, from 1851 to 1880 (Pencks Oeo^
graphische Abhandlungen, ii.: Wien, 1887). Some general laws of rainfall distribu
tion are beautifully illustrated in the maps which accompany Dr. Angot’s paper,
and tables of rainfall for 271 selected stations. At the first glance, the influence of
mountains in deflecting the water-vapour upwards into regions of lower temperature,
and so cooling and condensing it, is so apparent that one is inclined to say that
relief and rain maps are congruent. But a closer study of the great mountain
regions on the rainfall map shows that the central areas receive less rain than the
periphery, and the windward slopes more than the leeward. An area of minimum
rainfall is usually found not far from the foot of the lee side of the high ground; for
instance, in the upper Rhine plain, the upper valley of the Loire, and in the east
of our own islands. The winter rains are mainly cyclonic, and, owing to the low
temperature, are rarely heavy, save in the extreme western mountains, and rapidly
diminish towards the east, where even such lofty regions as the Alps receive compara
tively little rain. In February least rain falls over Europe as a whole, even when
due allowance is made for the shortness of the month. In spring the cyclone tracks
are often directed to the Mediterranean region, which receives abundant moisture,
while North-Western Europe has its minimum precipitation. As the summer
advances, and the temperature increases and permits large supplies of water-vapour
being formed in the lower regions, the mountainous districts, especially in the heart
of Europe, have very heavy rains. But the whole Mediterranean region is
exceedingly dry, and in July we have a most striking contrast between the wet
lyrd, where the rainfall is at its maximum, and the dry north of Italy, where it is
at its minimum. The need for maps of mean monthly rainfall, and not merely
seasonal ones, is clearly demonstrated in Northern Italy, where June is wet while
July is very dry. Autumn is rainy everywhere, especially along the Mediterranean
littoral. In October the regime of cyclonic rains begins, and the winter conditions
become apparent, but the vertical temperature-gradient is slightest about this
season, and so the atmosphere can hold much water-vapour, and the rains are
heavier than in the corresponding spring months.
Mode of Formation of the Dunes of Gascony. —M. E. Duregne, who has
been engaged for some years in careful investigations of the dunes which occur in
the coast region of the south-west of France, outlines the chief results of his con
clusions respecting their mode of origin in the Comptes Rendus (vol. 124, p. 1041).
The dunes with which his remarks are more specially concerned are those of the
Ieste-de-l»uch (Gironde) andj of Messanges (the Landes), and his surveys have
shown that these are incorrectly drawn on existing maps. Instead of forming