1. How cloth is made from warp and weft threads
Cloth is made from warp threads stretched vertically and weft threads passed horizontally. Each time a weft thread is passed, some warp threads are lifted and others are lowered to create a gap. This gap is called the shed, and the weft thread passes through it. [1]
The colors and patterns seen on the surface change depending on which warp threads are lifted. For detailed designs, the combination of lifted warp threads changes with every single weft thread. Choosing this combination by hand every time is an incredibly tedious task.
2. How one punched card sets the design for one weft thread
In a Jacquard loom, one card (called a pattern card) handles the design for one weft thread. On the card, each position corresponds to a specific warp thread. Holes are punched where the warp thread should be lifted, and no holes are made where it should not be lifted. These cards are tied together in the order of the pattern and set into the machine. [1]
The holes do not let the thread pass through. Instead, the holes are used to "select the needle." The next section explains how this movement works.
3. How needles meeting holes decide which threads are lifted
On the other side of the card, horizontal needles are lined up. When the card is pressed against them, the horizontal needles at the spots without holes are pushed back. The vertical needles connected to these pushed-back needles tilt, and their hooks detach. [1]
Next, when a knife-like bar rises, only the vertical needles that did not tilt because there was a hole are caught and lifted. The warp threads connected to these vertical needles are raised, creating the desired shed. [1]
The English Wikipedia also explains that where there is a hole, a rod passes through and does not move, but where there is no hole, it is pushed and moves. [2] If there is a hole, lift it; if there is no hole, do not lift it. With just this simple rule, the machine selects threads one by one.
Note: When the bar is lifted, only the vertical needles that did not tilt because there was a hole rise up, creating the desired opening. [1]
4. How earlier French inventors improved the idea before Jacquard
Jacquard patented this machine in 1804. However, French inventions had accumulated before that time. [2] In 1725, Basile Bouchon used a roll of paper with holes. He was followed by Jean-Baptiste Falcon in 1728, and Jacques de Vaucanson (listed as 1740 in Wikipedia). [2]
The Science Museum in London introduces Falcon’s loom as the first machine controlled by punched cards among all kinds of machines. The punched cards were linked like a chain, but an assistant had to place the cards against the needles by hand. [3]
Jacquard is said to have improved this method in 1804. Rather than seeing him as a lone genius, one might view him as the final runner in a relay of improvements.
5. How 24,000 cards made weaving of decorative cloth much faster
Because one person could watch a Jacquard loom, decorative cloth could be made more than 20 times faster than on traditional looms, according to estimates in histories of science. [4] However, this is an estimate from that commentary.
The silk portrait mentioned at the start was made in 1839 and required 24,000 cards. The Computer History Museum holds this artifact. [5] If one card equals one weft thread, this means about 24,000 weft threads were passed.
Preparing enough cards with holes punched in them is a huge job. But once they are made, the same pattern can be woven again and again.
6. How punched cards led to computers through Babbage, Ada, and Hollerith
The English inventor Charles Babbage saw Jacquard’s punched cards and is said to have seen the possibility of a "new and far greater power," leading him to conceive the Analytical Engine. [4]
Ada Lovelace wrote in an 1843 paper (notes) that the Analytical Engine would weave algebraic patterns just as the Jacquard loom weaves flowers and leaves. [6] It is a strange way to compare patterns of thread with patterns of mathematics.
Later, Herman Hollerith advanced the use of punched cards for recording information for the 1890 US Census. He is said to have founded a company that later became IBM. [2] However, sources do not state that Hollerith was a direct student of Jacquard.
7. How you can try punch-card patterns yourself or visit a museum
Things you can do today: Get a sheet of graph paper. Imagine one vertical column is one warp thread and one horizontal row is one weft thread. Fill in the squares where you want to lift the thread with a pencil. These filled squares are like the "holes." If you fill in row by row, a pattern appears. [1]
If you compare filled and unfilled squares to 1 and 0, you might notice it is similar to how computers record information.
Things you can do by going out: Check the official websites of textile regions or museums to see if they have displays of looms or cards before you visit. [3]
Official information: The materials from the Science Museum Group and the Computer History Museum listed in the sources below can be read with photos. [3] [5]