Fig. 16
It might be interesting to describe the various changes and attempted improvements that have been made on the original jacquard, but it would take up too much space, and many of them are of more historical than practical importance; some of them will be mentioned that may be interesting from a mechanical point of view, in connection with the descriptions of the machines, even though they have only been partially successful. Though a very different machine from what it originally was, the principle of the jacquard remains the same, and is not likely to be altered or superseded till a revolution takes place in the process of weaving.
Fig. 16a
A jacquard machine is simply a shedding motion by which a great variety of sheds can be formed; the larger the machine, or the greater the number of hooks it contains, the greater is the variety of shedding that can be produced by it.
If a jacquard is made small, with, say, from 16 to 48 hooks, it is called a dobby or shedding motion, and is used for working shaft mountings; but the ordinary jacquard machines have from 200 to 600 hooks, which have long cords, called the harness, connected to them, no shafts being required, as each hook has only a few cords tied to it, which can be raised independently of the others. The fewer the cords that are tied to each hook, the greater is the variety of shedding that can be made on the same number of warp threads, till, when there is but one cord to the hook, any thread or any number of threads can be raised independently of any of the others.