The “brains” of the Jacquard loom is a set of pasteboard cards that are perforated in accordance with a prearranged design. The warp threads, instead of being passed through the loops of two heddles, are passed through what might be termed individual heddles, one for each thread, or for a small group of threads. These consist of cords in each of which is an eyelet through which the warp thread passes. The cord is weighted at its lower end and its upper end is fastened to a hook in a box at the top of the machine. The hooks engage transverse bars known as “griffes” or “knives,” and when the griffes are raised, the hooks engaging them are also raised. In this way the warp threads that pass through the eyelets that are connected to the hooks are raised. But running horizontally across the hooks there are “needles” or rods with eyelets or bends in them through which the hooks pass. These needles may be moved lengthwise to make the hoops engage or disengage the knives. The mechanism is illustrated in Figure 70, where the knives are shown in section at _A_, the hooks at _B_ and the needles at _C_. For the sake of simplicity only eight hooks and needles are shown; in actual practice there are hundreds in a single machine. At the right-hand end of each needle there is a spring which pushes the needle toward the left, thereby bringing the hook through which it passes into position to be lifted by its griffe. At the left-hand side of the machine there is a card (_D_) which presses back the needles and thereby bends the hooks out of position to engage the griffes. However, there are perforations in the card through which certain of the needles can pass, letting the hooks they control engage the needles. The cards thus select the particular weft threads that are to be raised. In our illustration most of the needles have entered holes in the card, but the second, fourth and sixth from the top have been pushed back by the blank wall of the card and their hooks have been bent back clear of the griffes. Only four cards are shown in the drawing arranged in a four-sided box or “cylinder,” and the cards are successively presented to the needles. For more elaborate designs a large number of cards are used, arranged in a slatted belt, and these come successively into position. As many as thirty thousand cards have been employed to carry out a single pattern. [Illustration: FIG. 70.--DETAIL OF A JACQUARD LOOM] INVENTION OF THE KNITTING MACHINE