580 ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 62 



relative widths, in terms of the maximum width of the limb at its base, 

 is described in the caption for figure 6. 



It is of course impracticable to reduce the width of the limb to zero 

 at the tip. This would have no place for seating ("nocking") the 

 string, and because of the small width, the outermost several inches 

 of the limb would be mistable and tend to twist. Accordingly, in con- 

 structing the limb, sufficient width is left in the outermost 3 or 4 inches 

 to provide for a suitable nock and retain stability. To compensate for 

 the extra stiffness due to the added width, the thickness of the end of 

 the limb is reduced so as to approximate bending in this section on the 

 same radius with the rest of the limb. The approximation cannot be 

 close, because of the very small bendmg moment near the tip. The 

 corners of the limb are chamfered to reduce concentration of stresses. 



The new design, shown in plate 3, which in effect loads the limbs 

 uniformly and thus makes optimum use of their elastic properties, 

 made possible a reduction in their length by 10 to 15 percent, while 

 reducing hazard of breakage. A dividend was the possibility of mak- 

 ing the limbs of equal length, instead of keeping the lower limb 2 inches 

 shorter than the upper, as in the longbow. This is accomplished by 

 lengthening the rigid middle section sufficiently to provide the same 

 length of rigid section above the arrow as there is in the handle sec- 

 tion below the arrow, thereby keeping the bow symmetrical with re- 

 spect to the axis of the arrow, with the arrow nocked at the midpoint 

 of the string. Both limbs are now alike in dimensions and stiffness. 

 Such a limb has a period of vibration much shorter than that of the 

 equivalent limb of a longbow, the comparison between the two bows 

 being based on their exerting the same static force on the arrow at full 

 dravr. The new limbs therefore spring back faster, impart higher 

 velocity to a given arrow, and thus have greater efficiency in trans- 

 ferring their energy to the arrow. 



Experiments with bows developed along these lines proved them to 

 be far superior in efficiency to the longbow. Whereas the latter at 

 best transferred 40 percent of its stored energy to the arrow, the new 

 bows, according to measurement made both by Hickman and myself, 

 had above 75 percent. With efficiency about double that of the long- 

 bow, it can impart an initial velocity to a given aiTow about 40 percent 

 higher than that produced by a longbow. 



It seems appropriate at this point to quote from a letter which I 

 received from a distinguished scientist and friend in Washington after 

 I had sent him one of the new bows. He had been finding welcome 

 relief from strenuous responsibilities in military research and develop- 

 ment by practicing archery occasionally with the Potomac Archers, 

 where he used a longbow. Upon receipt of the new bow, he tried it, 

 then sent me the following comment : 



That is the doggondest bow I ever saw — and apparently that the Potomac 

 Archers ever saw. I took it down yesterday. The club was having an informal 



