and how they were produced. It remains to consider the question why the highland fir, as it is called in Rome, is inferior, while the lowland fir is extremely useful in buildings so far as durability is concerned; and further to explain how it is that their bad or good qualities seem to be due to the peculiarities of their neighbourhood, so that this subject may be clearer to those who examine it.
CHAPTER X
HIGHLAND AND LOWLAND FIR
1. The first spurs of the Apennines arise from the Tuscan sea between the Alps and the most distant borders of Tuscany. The mountain range itself bends round and, almost touching the shores of the Adriatic in the middle of the curve, completes its circuit by extending to the strait on the other shore. Hence, this side of the curve, sloping towards the districts of Tuscany and Campania, lies basking in the sun, being constantly exposed to the full force of its rays all day. But the further side, sloping towards the Upper Sea and having a northern exposure, is constantly shrouded in shadowy darkness. Hence the trees which grow on that side, being nourished by the moisture, not only themselves attain to a very large size, but their fibre too, filled full of moisture, is swollen and distended with abundance of liquid. When they lose their vitality after being felled and hewn, the fibre retains its stiffness, and the trees as they dry become hollow and frail on account of their porosity, and hence cannot last when used in buildings.
2. But trees which grow in places facing the course of the sun are not of porous fibre but are solid, being drained by the dryness; for the sun absorbs moisture and draws it out of trees as well as out of the earth. The trees in sunny neighbourhoods, therefore, being solidified by the compact texture of their fibre, and not being porous from moisture, are very useful, so far as durability goes, when they are hewn into timber. Hence the lowland firs,
