The Construction of the Crossbow
I. The bow must be immovably fixed in the stock.
II. The arm of the bow on one side of the stock, should not be even
1/8 in. longer or higher than its arm on the other side of the stock. A
piece of twine tightly fastened from one end of the bow to the other, with
a little bit of coloured silk knotted round the exact centre of its length,
will be a guide of much assistance when regulating the position of the
III. When the bow is fixed, a thread of cotton stretched from the centre
of one end of the bow to the other, should be in a straight line and not
pushed up at its centre by the surface of the stock.
The thread should cross 1/4 in. above the stock, so that when the bowstring,
which is 1/2 in. in diameter, is fitted to the bow, the lower edge of the
string will just lightly touch the groove in which the bolt is laid. There
will then be no friction to retard the force of the bow-string when the
crossbow is discharged.