Requirements in Bow Woods.—Nature has given us the forests which are the sources of wood for our various needs. But different woods have different mechanical properties. One kind is good for some particular purpose; another kind is better for another purpose. In spite of the almost countless species of trees, only a few have been found to produce real bow woods. There are some inescapable requirements in a good bow which can be produced by only these few woods.
The first requirement is cast, or the ability to give speed to the arrow. In other words, the wood must have "spring." This is fundamental. Even if a certain wood meets with every other specification desired but that of cast, it is not a good bow wood.
The second is durability. No matter how much spring is associated with a certain wood, if a bow made of it cannot withstand the repeated strain of drawing to full arrow distance, the making has been a waste of time.
The third requirement demands that the bow should not follow the string; that is, the limbs of the bow should resist taking a set in the direction the string is pulled. A comparatively small set in this direction is not very objectionable. Many good bows show a moderate amount after some use, but it should not continue to increase after further use.
There are certain other demands made of bow woods which may be less fundamental for they are dependent on personal preference to some extent. These are associated with the "feel" of the bow to the hand.
Perhaps tradition plays some part in the decision concerning the ranking of the recognized woods for bow purposes. Nevertheless, tradition has been careful not to list among the elect a mediocre wood. The woods described below are those out of which bows have been and are being made. The first three especially are among the generally recognized bow woods and, by general concensus of opinion, stand in a class by themselves.
Yew (Taxus).—This is the great bow wood of tradition, the wood which made the bows of the old English archers famous and which is prized today as perhaps the premier wood out of which they may be made. The yew for the bows of medieval England was mostly obtained from Spain and Italy (Taxus baccata). Unfortunately, what little of this fine wood is still growing in these countries may not now be exported. Fortunately a very good grade of yew (Taxus brevifolia) is found in fair abundance in our westcoast states. It is an evergreen which, under favorable conditions, may grow to more than 50 feet in height. It has a thin bark of a dark purple-red color and a narrow layer of cream-white sapwood under the bark. There is a well-defined line of separation between the sapwood and heartwood, the latter being of a reddish color. The wood has a specific gravity of 0.64; that is, in the dry state, it is 64 per cent the weight of water. It is fairly strong and hard for an evergreen.
While the tree, as just stated, may grow to a considerable size, it would seem that one grown under adversity tends to produce the better bow wood. So we often hear the statement that a yew bow of fine grain is better than one of coarse grain. The coarse grain means favorable conditions of environment with consequent rapid growth, while the fine grain represents adverse conditions and slow growth.
The writer has two yew bows of about equal weight in draw, one of fine grain and another of coarser grain. The latter has 17 lines (annual rings) to the inch and is almost perfect in its freedom from blemish and in straightness of grain; the former has about 45 lines to the inch, has two or three pin knots and a grain which undulates from one end of the bow to the other. Nevertheless, the fine-grained bow has better cast than the other. However, this single example is not of itself proof that fine-grained yew makes a better bow than coarse-grained yew. Indeed, some claim that this does not necessarily follow. On the other hand, there is a greater unanimity of opinion that yew grown at the higher altitudes is superior to that obtained on the lower levels.
The perfect yew stave is virtually non-existent, but sufficiently good staves or billets to make excellent bows are readily obtainable from a number of archery supply firms scattered over the country from coast to coast. Yet the yew is one of the most difficult woods to work up into a good bow. It submits readily to the tool, but because of the tendency of the grain to undulate throughout its length and twist from side to side, and also because of the common presence of the pin knot, it requires real art and skill to make a satisfactory bow of this material. Figure 15, A, shows a section of a yew bow stave. The light-colored strip is the sapwood.