It is obvious that in every country native timber is preferred, provided it can be obtained in sufficient quantity at a cheap rate; if not, it is imported from other countries. In Britain, the first and most important of all trees is, of course, our own oak, of which we have two species and several varieties, belonging to the genus Quercus.
The two species of oak natives of Britain, though greatly resembling each other in general appearance, may yet very readily be distinguished, when once their specific characters are pointed out. As these two species are very commonly confounded together, and as one of them is believed to afford a far more valuable timber than the other, it may be useful to note their difference, and exhibit the characters by which each may be known.
The true British oak, Quercus robur, (fig. 1) bears its acorns on a stalk, or peduncle (fig. 1, A), and hence it is sometimes called Quecus pedunculata, but its leaves grow close to the stem, without a footstalk, or at least with a very short one. In the other native species (fig. 2), these two characters are reversed: the leaves grow upon a footstalk, while the acorns are produced sessile, that is, sitting close to the stem (fig. 2, A); from which latter character this species has acquired the name of Quercus sessiliflora.
The above characters will, for the most part, be found pretty constant. At the same time, it may be remarked, that the oak is a tree subject to great variations; and accordingly individuals of each species occasionally occur, which in their characters are found more or less to approach those of the other. Quercus robur, for example, sometimes bears its acorns almost close to the stem, and sometimes Quercus sessiliflora will bear them on a short footstalk. The leaves, too, of each, frequently vary in the length of the petiole, or leafstalk. But in a general way (as already stated), each kind may be readily distinguished by the above obvious points of difference.
Both species are common in Britain, though Quercus sessiliflora appears to be not so generally distributed as the other; in many districts its growth seems to be principally confined to woods and coppices, where it sometimes occurs even in greater abundance than the common species. Quercus robur is believed to afford the more valuable timber of the two, owing, probably, to its being of slower growth. It is doubtful, however, whether the respective merits of each, in point of durability of timber, have yet been fairly put to the test. Where oak is grown in coppices, to be cut down periodically for poles, Quercus sessiliflora is at least a valuable, perhaps a preferable tree, on account of its more rapid and cleaner growth.
No certain specific characters, we are aware, can be derived from the mere size or shape of the acorns, or of the leaves. It may be mentioned, however, as a general, though not a constant rule, that Quercus sessiliflora usually bears very small acorns, and that its leaves are, for the most part, larger, and more regularly laciniated or notched, and consequently handsomer, as individual leaves, than those of Quercus robur. The foliage of the latter species, however, taken as a whole, is by far the more beautiful; its leaves, being smaller, and growing close to the stem, and not on footstalks, combine better, form more dense and compact masses, and exhibit to greater perfection those exquisite tufts, or rosettes, which constitute one of the peculiar charms of oak foliage.
The oak is far less used in civil architecture than formerly, although there are certain purposes in building to which it is still applied; but owing to its value and the demand for it for ships, and to the great labour required to work it, its place is now supplied by fir. The best oak is that which grows on cold, stiff, clayey soils, and is the slowest in arriving at maturity; and the colder the climate, or the higher above the level of the sea the tree grows, provided it be not stunted from severity of climate, the better the timber: hence Scottish and Welsh oak is more esteemed than that from the middle or southern counties of Britain. Our own island does not produce this timber in sufficient abundance to supply the demand, and large quantities of oak are imported from different countries, especially from Prussia and Canada. There are four kinds of oak used in the Royal Dock-yards,—Welsh, Sussex, Adriatic, and Baltic,—besides two others, termed African oak, employed in different parts of the vessels, according to the qualities requisite for the particular purpose. Next to our own oak, that from the shores of the Baltic is by far the most esteemed.
In domestic architecture, oak is only used in the largest and best buildings, occasionally for the principal beams; but its chief use is for door and window frames, sills, sleepers, king-posts of roofs, for trussing fir girders, for sashes, for gates of locks, sluices, posts, piles, &c. The timber called African oak, used in the navy, is wood of a different genus.
Wainscot is the wood of a species of oak, imported from Russia and Prussia in a particular form of log.