The first of the series of scientific researches on the bow is reported by Hickman in the Journal of the Franklin Institute. The experimental study was directed towards finding the effect of fiber backing on the weight and efficiency of a bow. In most of the experiments reported, a lemonwood bow drawing a little over 30 pounds at 27 inches was used. To obtain efficiency values, velocity measurements on the arrows shot with the bow had to be made. For this purpose, a modified form of Aberdeen Chronograph was used, and data were obtained which enabled the investigator to plot curves showing displacement, velocity and acceleration of the arrow, while during twenty to thirty thousandths of a second, it was being driven forward by the string. The curves are shown for four different masses of arrow, namely 230, 365, 545 and 635 grains, all shot with the fiber-backed bow, and then repeated with the fiber backing removed. Other curves are shown, giving the relationship between mass of arrow and velocity, indicating higher velocity for all arrow weights when the bow was fiber backed than when the backing was removed. Removal of the backing changed the drawing force from 32 to 30 pounds, and a new fiber back raised it again to about 31.5 pounds. With the original fiber back, a 350-grain arrow had a velocity of 134 feet per second; with fiber removed, 125 feet per second; with new fiber back, 132 feet per second. All the shooting was done with the aid of a shooting machine, so that variations which might have been introduced by hand shooting were avoided.
Efficiency curves are also given for the three cases, showing that, with a 350-grain arrow, the efficiency was 63% originally; with fiber back removed, 56%; with new fiber back, 61%.
Hickman next tested an osage orange bow, (a) backed with rawhide, drawing 49 pounds at 27 inches. With (b) rawhide removed, it drew 46 pounds; (c) backed with .16 fiber, 45 pounds; (d) backed with .046 fiber, 46 pounds. For cases (a), (b), (c) and (d), the efficiencies for a 400-grain arrow were 43%, 46%, 47% and 48%, respectively.
This indicated that the rawhide (which was almost 1/16 inch thick) actually reduced efficiency, and that the fiber gave a very slight increase over that of the unbacked bow.
It is necessary to exercise caution in drawing conclusions from these, as from any experimental results obtained with bows and arrows. It would be erroneous, for example, to conclude that backing a bow increases its efficiency; or that backing with fiber increases, while backing with rawhide decreases the efficiency. What definite conclusions, then, may be drawn? Not any that are generally applicable to all bows; but the experimental facts of Hickman's work have provided us with information from which we may arrive at the following highly probable conclusions: