FIG. 166.
The pattern extends to seven dents, and as the pin N ([Fig. 165]) occupies four dents, it will be necessary to have eleven spaces, each equal to a dent, in the groove. The first pick in the pattern floats over two dents or four ends, and therefore the groove at this point must be six spaces wide—four for the pin, and two for the space it has to move through. Before the next movement of the rack, the wheel will have been turned one tooth, and at this point the groove moves one space further to the left. For the third pick both sides of the groove are moved one space to the left, and the size of the float will remain the same as in the second pick, but it will float over different ends. The groove gradually gets wider until the tenth pick is reached, when it narrows down again until it repeats on the twenty-fourth pick.
If there are two spots set “one and one” in the pattern, the wheel requires one tooth more than the picks in a repeat, in consequence of changing from one spot to the other.
CHAPTER IX
AUTOMATIC WEFT-REPLENISHING DEVICES
THE history of the development of the power-loom, from its inception by Dr. Cartwright, has been written on many occasions. That story relates how old methods have been improved or else displaced by new ones of greater efficiency, and how the modern power-loom has, by the effort and skill of the pioneers of industry, been brought gradually to its present state of mechanical perfection. This march of progress goes on steadily, continuously, and almost imperceptibly to those who are not immediately interested in or affected by the changes that are thus wrought; until by some special circumstance they suddenly and unexpectedly arrest attention, and it is realized for the first time that a new era has dawned and promises changes of great magnitude.
The advent, now fifteen years ago, of what are popularly described as “automatic looms” marked the beginning of events of considerable importance to the weaving industry in particular, and to the textile industry in general. The essential element which distinguishes these looms from those of ordinary construction consists of special apparatus attached to, and forming an integral part of, the looms, which are thereby enabled to replenish weft automatically from a reserved supply conveniently held in readiness. This briefly constitutes the automatic element of the looms. There are, of course, many auxiliary attachments that are incidental to the weft-replenishing devices, and which increase their efficiency and productiveness.
Notwithstanding the comparatively short period that has elapsed since the adoption, on a commercial scale, of these looms, such has been the activity of inventors and loom-makers both at home and abroad, that looms of this class have already been designed in an almost endless variety of forms, some of which differ essentially in construction and operation, whilst many others differ only in minor details of construction. Most of these, however, have never matured to practical forms. Many have never escaped the secret confines of the experimenting room. Others have been doomed to premature failure, whilst some three or four types of real merit are struggling hard for supremacy. Which of the competing types will win, ultimately, is at the present time matter for conjecture. This will depend entirely on the type that will best meet the requirements of manufacturers, and the one that will endure the test of experience and time, which alone can be the deciding factors. But, for certain classes of fabrics for which they are suitable, it is safe to predict that automatic looms of some approved type are permanently established in the trade.