Showing posts with label mechanism. Show all posts
Showing posts with label mechanism. Show all posts

Wednesday, July 12, 2023

The Beauty is in the Cards

 

QUESTION: One of my passions is to visit historic houses. In many of them from the 19th century, I often see beautiful coverlets on the beds and sofas. House docents have said that women produced these coverlets on a special type of loom. I know they were done on a special kind of loom, but I forget what it was called. Can you tell me more about this special loom?

ANSWER: The unique designs of those coverlets were possible by the invention of the “Jacquard” loom. But coverlets weren’t the only types of weaving produced on this loom. By the 1850s, factories began using larger versions of the Jacquard to produce not only coverlets but two-sided carpets. Before the Jacquard loom, complex, figural designs were more difficult to produce alone on the same loom. 

Joseph-Marie Jacquard, a French weaver and merchant, patented his invention in 1804, he revolutionized how patterned cloth could be woven. His machine made it possible for complex and detailed patterns to be manufactured by unskilled workers in a fraction of the time it took a master weaver and his assistant working manually. 

A Jacquard loom wasn’t a particular type of loom but a control mechanism that’s added to a variety of looms. 

The spread of Jacquard's invention caused the cost of fashionable, highly sought-after patterned cloth to plummet. It could now be mass produced, becoming affordable to a wide market of consumers, not only the wealthiest in society.

To weave fabric on a loom, a weaver passed a thread, called the weft, over and under a set of threads, called the warp. The weaving of threads at right angles to each other  formed the cloth. The particular order in which the weft passes over and under the warp threads determined the pattern. 

Before the Jacquard system, a weaver's assistant, known as a draw boy, had to sit on top of a loom and manually raise and lower its warp threads to create patterned cloth. But this was a slow and laborious process.

The key to the success of Jacquard's invention was its use of interchangeable cards into which small holes had been punched, which held instructions for weaving a specific pattern and took over the time-consuming job of the draw boy. 

When fed into the Jacquard mechanism, fitted to the top of the loom, the cards controlled which warp threads should be raised to allow the weft thread to pass under them. With these punch cards, Jacquard looms could quickly reproduce any pattern a designer could create, and reproduce over and over.

The designer first painted a pattern onto squared paper. Then a card maker translates the pattern row by row onto the punch cards. For each square on the paper that wasn’t painted in, the card maker punches a hole in the card. For each painted square, he didn’t.

The cards, each with their own combination of punched holes corresponding to the part of the pattern they represent, were then laced together, ready to be fed one by one through the Jacquard mechanism fitted to the top of the loom. 

When the mechanism pushed a card towards a matrix of pins in the Jacquard mechanism, the pins passed  through the punched holes, activating hooks to raise their warp threads. Where there were no holes the pins press against the card, stopping the corresponding hooks from raising their threads. 

A shuttle then travels across the loom, carrying the weft thread under the warp threads that have been raised and over those that have not. This repeating process causes the loom to produce the patterned cloth that the punch cards have instructed it to create.

The Jacquard mechanism is a device fitted to a loom that simplifies the process of manufacturing textiles with such complex patterns as brocade, damask, and matelassé. The resulting ensemble of the loom and Jacquard machine is then called a Jacquard loom.

Unlike regular looms which are faster and less expensive to operate, looms with a Jacquard mechanism are slower and costlier to operate.

Threading a Jacquard mechanism was so labor-intensive that weavers threaded many looms only once. They then tied subsequent warps into the existing warp with the help of a knotting robot which tied each new thread  individually. Even for a small loom with only a few thousand warp ends, the process of re-threading could take days.

Factories had to choose the looms and Jacquard mechanisms to suit the requirements for their product. They used larger capacity machines or multiple machines which allowed greater control over bigger designs woven over the width of the loom.

The Jacquard attachment first appeared in America in the early 1820s, probably by one of the many German, English and French hand weavers who had immigrated from their native countries in Europe. These immigrant weavers tended to settle in areas with populations of their own ethnic group and near sources of good quality wool. Many brought some type of Jacquard attachment or at least the experience to use one. Some even developed their own devices based on Jacquard's idea and patented them in the U.S.

Jacquard weavers derived the patterns and motifs they used from well-known folk traditions of Western Europe. The designs of most Illinois coverlets can be traced back to Ohio and Pennsylvania coverlets. The center field patterns were either a large, repeated symmetrical motif on two-piece ones or a centered medallion on single-width coverlets. Floral motifs appeared most frequently, in the Four Lilies and Sun-burst, Four Roses, Octagonal Four Roses, Four Leaves and Four Acorns, and Four Bellflowers patterns. Star and Sunburst designs were also common.

Families in the 19th century often used Jacquard coverlets when taking long journeys in a horse-drawn carriage or stage coaches. In America, the practice of making coverlets using Jacquard looms began to fade during the fourth quarter of the 19th century. The import of cheaper materials into the U.S. became a difficult hurdle for weavers to overcome.

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Wednesday, May 20, 2015

For Every Meat There is a Turn



QUESTION: I love old mechanical things. Recently while rooting through a box of old junk at a monthly flea market, I came across an unusual item. It looks like a round can from which protrudes a cylinder. On the end of the cylinder is an odd-shaped ring and in the side of the can is a hole with a place to insert a key. Can you tell me what this is and something about it, if that’s possible?

ANSWER: It looks like you’ve found an antique spitjack. However, some of its parts are missing.

Today, you can go to any supermarket and purchase a fully roasted rotisserie chicken or turkey breast. But back in the 18th century, that wasn’t possible. All meats had to be slow roasted on a long pole called a spit over the fire in a huge, walk-in kitchen fireplace. And to do that evenly, it took man or woman power. Wives, children, servants, or slaves had to stand by the fire and slowly turn the meat until it was done. This had to be one of the most boring jobs in the 18th and early 19th centuries, so no one enjoyed doing it.

Roasting meat on a spit dates as far back as the first century B.C.E. During Tudor times, someone even came up with an ingenious way to have a dog provide the power to turn the spit—the dog ran in a treadmill linked to the spit by belts and pulleys. But it wasn’t until the 18th century that things got a little easier for cooks. It was then that the weight or clock jack came into being.

Descending stone, iron, or lead weights powered most of the spit-turning mechanisms, or more commonly spitjacks, used by Colonials and their British counterparts. In England, cooks referred to them as weight jacks, but in America, they came to be known as clock jacks because they used a clockwork mechanism to wind a spring used to turn the spit.

Earlier jacks of this type had a train of two arbors or spindles. Later ones had a more efficient train with three arbors. Those made and used in England had a governor or flywheel set above the engine as opposed to being located within the frame and to one side—to the right for a two train works and to the left for one with three trains. These weight jacks also contained a flywheel within the frame, usually at the
in a bell-like arch at the highest part of the frame.

In 1792, John Bailey II, an American clockmaker, patented the first steam-driven jack. However, the Turks used a mechanism similar to Bailey’s jack back in the mid-16th century.

Another type of roasting jack, the smoke jack, appeared in the early 17th century. This jack moved by the flow of the smoke from the fire over the sails of a horizontal wheel which lay sideways. By placing the wheel in the narrowest part of the chimney where the motion of the smoke was the fastest and where the greatest amount would strike the sails, the mechanism would slowly turn the spit, thus roasting the meat. But this type of jack had its downside since the speed of the jack depended on the draught of the chimney and the quantity and strength of the fire in the fireplace.

The type of jack you purchased is called a bottle jack because of its bottle-shaped hydraulic lifting device. A brass shell contains the clockwork motor. Introduced in the late 18th century, it replaced the earlier and simpler dangle spit. When the cook set the weights, the spit turned, eliminating the need for manual labor for approximately 30 minutes, after which the cook would have had to readjust the weights. Bottle jacks continued to be made and used until the early 20th century.

If your jack had all of its parts and was in better condition, it would sell for around $400.