Know that the construction of the bow varies for three different things: places, individuals, and objects.
Regarding the variations in places: some archers maintain that the bow with which an archer shoots from above downward should have siyahs of equal size, that is, one not longer than the other; while the bow with which an archer shoots from below upward should have its lower siyah longer than the upper. Otherwise, its construction remains the same: uniform. This was described in the section on the different kinds of bows, where it was explained that the upper siyah of the bow together with the upper arm and the width of a finger on the grip constitute one half of the bow, while the remaining part of the grip with the lower arm and siyah make up the other half. Such is the verdict of the master archers.
The construction of the bow varies, too, in the prevalence of some of its parts over the others as a result of different climatic conditions. Thus, in regions extremely hot or extremely cold, as well as in places which are very damp and humid, the suitable bows are those which have abundant wood and wide limbs; whereas in regions of moderate heat, cold, and humidity, the suitable bows are those which have an abundance of sinew and narrow limbs. The latter are also suitable for use in moderate seasons, such as the spring. In regions the climate of which tends to be cold and damp, like Syria and Andalusia, the suitable bows are those which are scant in wood, abundant in horn, and moderate in sinew and glue.
The Bedouins of the Hijaz use nothing except bows made of nab‘, or shawḥaṭ, or shiryān wood, while those who live near water and nearby groups back their bows with sinew and face them with goat horn, as we have already mentioned, because of the intense heat. According to some experts, bows made of nab‘, shawḥaṭ and shiryān wood are useless outside the Hijaz. Others have recommended that in countries of excessive heat the sinew should be saturated with glue made of the best parchment, which is characteristically moist and, therefore, suitable for hot regions but not for those which are cold and humid.
Variations in the construction of bows, because of the different archers who are to use them, are accounted for by the fact that experts have agreed that for each archer there is a particular bow best suited to his own build. They have also agreed that such a bow should be measured with relation to the arrow which is to be shot in it and that the individual archer is, in turn, the basis of that arrow. They have, however, disagreed concerning the ratio in length of the bow to the arrow, with some maintaining that the bow should be, when unstrung and measured from one extremity to the end of the horn of the other limb, the width of three fingers shorter than its arrow. This is the opinion of abu-Hāshim, who claims that the arrow of the short bow is quicker in release, stronger in hitting, and deadlier in aim. Others have maintained that the bow should be, when unstrung and measured from the end of one horn to the end of the other, exactly the length of the arrow. This is the opinion of Ṭāhir and Isḥāq, who claim that if this portion of the unstrung bow were longer than the arrow such a length would militate against the cast of the arrow and the power of its impact. On the other hand, if it were shorter than the arrow, the strength of the bow would overcome the archer, who would then be unable to draw it to the full length of the arrow except with difficulty and with the result that his left arm would be shaken, his aim spoiled, and his effectiveness gone, since they depend on the ability of the archer to control his bow. Furthermore, no archer using too short a bow can ever operate it well; frequently it is broken or its strings snap.
Still others have maintained that the arrow should measure exactly the length of the strung bow; while some have said that the correct length of the arrow should be exactly that of the strung bow if the siyahs were long, and exactly that of the unstrung bow if they were short. The question of the ratio of the length of the arrow to the stature of the individual archer will be discussed later under a special heading.
Variations in the construction of the bow in accordance with the different objects for which it is to be used result in five kinds of bows: a bow for warfare, another for training and practice, a third for target shooting, a fourth for competition, and a fifth for trick shooting.
The bow for warfare should be, in strength, equal to that of the archer himself, with short siyahs—lest they hit the shield or whatever the archer carries—and a straight grip. It should have more horn than wood and, likewise, more sinew than wood. Furthermore, it should not be excessive in recurvature, so that it may be quickly strung and quickly unstrung. Recurvature (ta‘jir) is the curving of the bow toward its back when unstrung, and is the opposite of incurvature (inḥinā’) which is the curving of the unstrung bow toward its belly so that it appears to the eye almost strung. It should have more horn than wood because both the weight of the bow and its force depend upon the horn—the more horn it has, the stronger it is—although it is then more apt to become crooked in regions of unsuitable climatic conditions, while the more it has of wood and sinew, the straighter it remains, although its strength is then diminished. Therefore, one should strike a happy medium inclining toward the sparing use of horn.
The training or practice bow should be a little stronger than the capacity of the archer. After a little use it becomes more manageable. He should then increase its weight by adding to it one and a half dirhams of sinew. This operation should be repeated whenever the bow becomes too flexible and loses strength, until it has again reached the full limit of the archer's capacity. Furthermore, the training bow should have wide arms, a rounded grip, and strong siyahs. Its sinew should exceed both its horn and its wood.