The modern rotl is approximately equal to the English pound avoirdupois, except in some localities around the eastern shore of the Mediterranean where it varies from 3.93 to 6.35 pounds. These higher values can be eliminated at once from our consideration as they would give bows of absurd magnitude. It is almost certain, however, that the rotl referred to in the manuscript was equal to our pound troy and not to our pound avoirdupois. At that time it was the legal weight of Islam and was derived from the cubit of al-Ma’mūn, or Black Cubit, as follows:
   Two-thirds of the Black Cubit of 21.28 inches gave the Black Foot of 14.186 inches. A cubic Black Foot of water weighed approximately 720,000 grains. This was divided for convenience into 125 parts of 480 grains each, called an uqīyah, which is the same as our troy ounce. Twelve uqīyahs, or troy ounces, made one rotl, or troy pound, of 5,760 grains. We will call it the Ancient Arabic rotl and base our calculations upon it.

The bow of 200 rotls has the greatest weight that is cited by the author. It is enough in itself to prevent us from adopting the modern rotl of one pound avoirdupois because a bow of 200 pounds is beyond ordinary human strength. Even by the Ancient Arabic rotl it would weigh 165 pounds. This is still indicative of an enormously strong bow which could be drawn only by men of gigantic strength and long training; yet there are recorded feats of Turkish archery which show that such athletes existed and some Turkish bows of nearly as great a weight are yet in existence. We must believe that such bows were actually used in oriental warfare. In America, bows of about that strength have occasionally been shot by hand in competitive flight shooting, and bows up to 220 pounds have been shot—for distance only—by drawing with both hands against the feet; like rowing a boat, sitting down.