It will be noticed that the knives are leaning a little, and the reason for this will be apparent, as if they were not leaning they would catch the tops of the hooks in coming down, and would break or bend them. The sloping position enables the knives in coming down to press back the tops of the hooks and so get under them, ready for the next card to be pressed against the needles. The knives should come down low enough to be quite clear of the hooks, and therefore in this machine there is a considerable dwell when the shed is closed.
The harness for a straight-over pattern is mounted as shown at Fig. 107. In order to prevent confusion the connection of the cords to the machine is not shown, but the numbers on the line A represent the hooks in the machine to which the cords are to be attached. The “comber-board” or “cumber-board” B is a frame into which perforated slips are fitted. These slips are perforated to different degrees of fineness, the fineness being regulated by the number of ends per inch required in the cloth to be woven. The lingoes, L, are metal weights, and serve the purpose of keeping the mails down. MM are the mails, through which the warp threads are drawn in the order shown by the numbers, beginning at the back left-hand corner. The draft in straight-over patterns is always taken in this way in Jacquard weaving, although it is not compulsory. The harness is built with linen thread, and the method of tieing the lingoes to the hooks will be understood from the diagram.
When one lingoe has been connected to each of (say) 400 hooks, the first pattern is complete. Supposing there are 100 ends per inch, the pattern will occupy 4 inches, and therefore if cloth is required 28 inches wide in the harness, there must be seven lingoes attached to each hook, making seven patterns, or seven repeats of the pattern, in the width of cloth. Thus when one lingoe has been tied to each hook, beginning with the first and ending with the 400th, another is connected to each hook, beginning again with the first; and when this is done other patterns are formed in the same manner until the required number is complete.
It is important to have a clear understanding as to which is the hook which lifts the first end in the draft. This hook is the one connected with the bottom needle in the last row on the 25-side of the machine. As we stated previously, a 400s machine has 400 hooks arranged in 50 rows of 8, or 8 rows of 50 hooks, and in addition there is always a spare row of hooks, making 51 rows in all. As it is necessary to lace the cards in the middle as well as at the sides, a space has to be allowed for the lace holes, and therefore the machine is divided into two parts by a space between the 26th and 27th rows.