The jack loom is a horizontal loom; i.e. the warp runs horizontally and most of the size is front to back, not up and down. The weaver can sit on a bench. With the vertical looms, like those still used in Scandinavia and previously in Greece, the warp threads hang down and the weaver must stand on a stool or the floor itself must be lowered to provide enough room.
A loom this size could easily be put into the back of a wagon and transported from place to place, as I have my main character/detective doing in my historical mysteries. This is a back view, by the way. The white canvas is for the back apron. I prefer to have my finished cloth roll up on the back beam so i tie on the warp threads to the back and then thread them through the heddles and the reed.
Heddles; what are they? I’ve mentioned them several times and then someone emailed me and said I don’t know what heddles are. Well, mine are long metal wires with an eye exactly like a needle. Mine are made of metal, but the looms I saw in Greece had thread heddles. I think I would find weaving with those confusing.
In the first photo, it is possible to see three of the four sheds. Each one has its own set of heddles. Threaded and tied up to the treadles, these sheds make it possible to weave many patterns.
And finally, the reed. The dents, or spaces, determine the fineness of the fiber and is another mechanism for keeping each thread smooth and untangled. I hope you can see the spaces here. Weaving with silk, for example, requires a reed with many many slots,