The Kind of Heddles Required for Compound Harness.
The eyes of these heddles are much longer than those of common heddles. They must be sufficiently long to allow the six movements illustrated in [Fig. LXX.] to [LXXV.], hence the height of these heddle eyes will influence the height of the shed.
Working the Compound Harness by a Separate Machine.
For working compound harness a separate small witch-loom is generally used, thus saving, to a great extent, the Jacquard cards. In this manner the ground may be easily altered without changing any cards, it being only necessary to change the small set of cards on the witch-loom controlling one repeat of the body weave for the harness. The number of picks for the harness can also be readily adjusted to one change in the Jacquard figure without disturbing the cards of any consequence. For example: in manufacturing a damask fabric, suppose four harness picks make one change of figure in the Jacquard machine, and it is necessary to reduce these four picks to one change of figure, on account of having to use some heavier filling, or other similar reason; this alteration can be easily made when using two separate machines.
Number of Compound Harness to Use.
Fig. LXXVI.
The number of harness used is regulated by the weave required for raising, and the weave required for lowering.
The number of harness may vary to a large degree, as we may use any suitable weave from the 4-leaf twill up to the 16-leaf satin. As a general rule, for fine damasks we use the 8-leaf satin, requiring 8 harness.