This section is from the book "The Manufacture Of Boots And Shoes: Being A Modern Treatise Of All The Processes Of Making And Manufacturing Footgear", by F. Y. Golding. Also available from Amazon: The Manufacture Of Boots And Shoes.
There are many varieties of machines for stitching uppers. Some only make one row of plain stitching at an operation, while others will make two, three, or more lines of stitching simultaneously. Machines of this class are of either the flat-bed, cylinder, post, or pillar description. Machines are also manufactured for automatically making fancy or ornamental stitches - such as half-chain, zigzag, overseaming, crewel-work, etc. Another type is used for making button-holes, lace-holes, etc. Motion may be derived from foot or power, the latter being obtained from steam, gas, or other engine. The use of electric motors has many advantages, especially when the stitching-room is located at a considerable distance from the main source of power, or where an irregular arrangement of the machines is required.
(6) Arrangement for determining the length of stitch, viz. the feed.
(c) Appliance for taking the thread and forming the stitch, viz. the looper, or shuttle, or rotating hook.
(d) Contrivance for keeping thread or threads taut, viz. the tension.
(e) Arrangement for holding material in position while stitch is being formed, viz. the presser or clamp.
These results should be accomplished with the least possible strain to the sewing medium, whether it be silk, thread, or cotton. The best type of machine is - other things being equal - that one which deposits the thread in the material stitched with the minimum of injury. Friction points should be carefully studied when making a selection, as well as the class of stitch given by the machine.