THE POLISH LAND 33
still further. The Amber Road of ancient times, and the medieval Prussian Road,
both traversed Polish territory at this point, whilst countless hordes of barbar-
ians, ancient and modern, have all poured through it on their way to fortune and
infamy.
The resultant structure of Poland is one of an irregular grid, a lop-sided frame
in which the dominant horizontal warp, is offset by the vertical weave of the
rivers. In terms of human activity, it gave every facility for movement and tran-
sit, which was matched in early times by favourable opportunities for perma-
nent settlement.
'Life-support capacity' is an ugly but useful piece of jargon invented to
express the product of all the factors which encourage or inhibit human settle-
ment in any particular location. In absolute terms, it is highest in the sub-
tropical valleys of the Yangtse, the Euphrates, or the Nile where civilization first
flourished, and lowest in the middle of Antarctica or the Sahara. On the
European scale, it has usually been high on the coastal strips of the
Mediterranean islands like Crete or Sicily, or in the northern valleys of
the Rhine, the Seine, or the Thames, and low in the taiga and tundra belts of
Scandinavia and Muscovy. In Poland, its level is mid-way between that
of Western Europe and that of Russia. Taking Warsaw as a central point of ref-
erence, the latitude of 52^0 N gives strong summer sunshine, and a hot summer
of three months' duration. The climate is continental, with marked seasons, but
lacking the worst extremes of summer drought, winter cold, or spring floods
which are common further east. Permafrost is unknown and storm-damage is
rare. The minimum daily temperature in January averages -3° C (z6° F), the
maximum in July 19° C (66° F). Precipitation at 559 mm. or 22 inches is rather
low, but rain falls mainly in the agricultural months — 11 inches between May
and August. The number of days entirely below freezing-point varies from 30 to
- Snowcover lasts up to 60 days, river-ice up to 40 days, and the growing sea-
son up to 180 days. Wind exposure, especially from the cold easterlies, is con-
siderable, but local wind cover is adequate, especially in the river-valleys and
behind high-standing timber. Cloud cover which reaches 150 days per annum,
is common in the winter months, and takes the edge off the most extreme cli-
matic conditions. Warsaw, of course, is located in one of the least favourable
districts of central Poland, and it would be quite possible to find other areas not
too distant, in Lower Silesia or in Malopolska, where the winter is shorter, the
sun brighter, the rainfall higher, the soil richer, and where the growing season
reaches an impressive 225 days. In the realm of vegetation, central Poland is still
within the normal range of the European mainland. The beech-line runs south-
eastwards from the Vistula estuary to the Carpathian foothills. The oak-line
runs in the same direction but much further east. Warsaw itself lies in an area of
rye and potato cultivation, but the limit of wheat production lies much further
to the north and east. The stock of natural fauna was once extremely rich,
and included tarpan, bears, bison, and wolves as well as the more familiar game
animals. It was not seriously diminished until the twentieth century, when