A comparative test of various strings was made to determine which material is the strongest for bows. Number 3 surgical catgut is apparently a D string on the violin. Taking this as a standard diameter, a series of waxed strings of various substances were made and tested on a spring scale for their breaking point. The results are as follows:
Horsehair breaks at 15 pounds.
Cotton breaks at 18 pounds.
Catgut breaks at 20 pounds.
Silk breaks at 22 pounds.
Irish linen breaks at 28 pounds.
Chinese grass fiber breaks at 32 pounds.
This latter, with similar unusual fibers, is not on the market in the form of thread, so is of no practical use to us.
We use Irish linen or shoemakers' thread. It is Barbour's Number 12. Each thread will stand a strain of six pounds; therefore, a bowstring of fifty strands will suspend a weight of 300 pounds.
A target bow may have a proportionately lighter string than a hunting bow because here a quick cast is desired; but in hunting, security is necessary. We therefore allow one strand of linen for every pound of the bow.
This is the method of manufacturing a bowstring as devised by the late Mr. Maxson and described in American Archery. Some few alterations have been introduced to simplify the technique.
It is advisable to take the threads in your hands as you follow the directions.
If you propose making a string for a sixty-five-pound bow, it should have about sixty threads in it, and these are divided into three strands of twenty threads each. Start making the first of these strands by measuring off on the bow a length eight inches beyond each end--that is, sixteen inches longer than your bow. Double your thread back, drawing it through your hand until you reach the beginning. Now repeat the process of laying one thread with another, back and forth, until twenty are in the strand. But these must be so arranged that each is about half an inch shorter than the preceding, thus making the end of the strand tapered.
When twenty are thus stroked into one cord, they are heavily waxed by drawing the strand through the hand and wax, from center to the ends, each way. Now roll the greater part of this strand about your fingers and make a little coil which you compress, but allow about twenty-four inches to remain free and uncoiled. Thus abbreviated it is easier to handle in the subsequent process of twisting it into a cord.
Make two other strands exactly like this, roll them into a compressed coil and lay them aside. Now to form the loop or eye it is necessary to thicken the string at this point with an additional splice. So lay out another strand of twenty threads six feet long. Cut this into six pieces, each twelve inches in length. Take one of these and so pull the ends of the threads that they are made of uneven length, or that the ends become tapered. Wax this splice thoroughly; do this to each one in turn.