To Cut a String With Your Hands
With a little practice, and some briskness of movement, you may be able to break a string of considerable thickness by proceeding as follows:
Wind the string round your left hand, so as to make a loop, as shown in the figure. Pass it three or four times round the fingers to insure the solidity of the loop. Seize firmly the other end of the string with your right hand, around which you wind it three or four times, then give a brisk pull. The string will be clean cut at the junction of the loop in the left hand.
When the knack is well acquired, one may break the string on two fingers only, by following always the same theory as above.