4. The material of which the object is formed must always be worked in the most natural and appropriate manner.
5. The most convenient or appropriate form for an object should always be chosen, for unless this has been done, no reasonable hope can be entertained that the work will be satisfactory; for the consideration of utility must in all cases precede the consideration of beauty, as we saw in our first chapter.
Having made these few general remarks, we must consider the structure of works of furniture. The material of which we form our furniture is wood. Wood has a "grain," and the strength of any particular piece largely depends upon the direction of its grain. It may be strong if its grain runs parallel with its length, or weak if the grain crosses diagonally, or very weak if the grain crosses transversely. However strong the wood, it becomes comparatively much weaker if the grain crosses the piece; and however weak the wood, it becomes yet weaker if the grain is transverse or diagonal. These considerations lead us to see that the grain of the wood must always be parallel with its length whenever strength is required.
For our guidance in the formation of works of furniture, I give the following short table of woods arranged as to their strength:—
Iron-wood, from Jamaica—very strong, bearing great lateral pressure.
Box of Illawarry, New South Wales—very strong, but not so strong as iron-wood.
Mountain ash, New South Wales—about two-thirds the strength of iron-wood.
Beech—nearly as strong as mountain ash.
Mahogany, from New South Wales—not quite so strong as last.
Black dog-wood of Jamaica—three-fourths as strong as the mahogany just named.