This section is from the "A Complete Dictionary of Dry Goods" book, by George S. Cole. Also available from Amazon: A complete dictionary of dry goods and history of silk, cotton, linen, wool and other fibrous substances,: Including a full explanation of the modern processes ... together with various useful tables.
The Spool Thread Of To-Day, however, is not of the grade made before sewing machines became a modern factor. The early manufactured thread was but three-cord, and took its number from the size of the yarn from which it was made; for instance three strands of No. 60 yarn made No. 60 thread—though in point of fact, the actual calibre of No. 60 thread would equal No. 20 yarn - being three No. 60 strands combined. When the sewing machine came into market as the great consumer of thread, the thread had to be made a smoother product than formerly was required for mere hand needles. This was accomplished by making the thread of six cords instead of three. As thread numbers were already established, they were not altered for the new article, and consequently at the present time No. 60 six-cord and No. 60 three-cord are identical in size as well as number. To effect this, of course, the six-cord thread had to be made of strands just twice as fine as that demanded by the three-cord; hence No. 60 six-cord is made of six strands of 120 yarn, No. 50 being made of six strands of No. 100 yarn, etc. All sizes of six-cord thread are made of six strands each twice as fine as the number designated by the label, while three-cord thread is made of three strands of same size yarn as is designated by the number on the label. This is the whole of the thread measurement.
The State Of Maine turns out nearly all of the spools on which the thread of this country is wound; in oxford county alone hundreds of thousands of feet of logs being cut and sawed into spool timber annually. These strips are sent to the spool factories where they are quickly worked into spools by the most ingenious labor-saving machinery. Almost all the spools now made are produced from birchwood, and the machinery used in their manufacture has been brought to such a degree of perfection as to reduce their cost to the lowest possible figure. The wood is first sawed into sticks four or five feet long and seven-eighths of an inch to three inches square, according to the intended size of the spool. These sticks are thoroughly seasoned, sawed into short blocks, and dried in a hot-air kiln at the time they are sawed, holes being bored perpendicularly through each block, which is set on end under a rapidly revolving long-shaped auger. At this stage one whirl of each little block against some small knives that are turning at lightning speed fashions it into a spool after the manner of the pattern provided, and this, too, at the rate of one a second for each set of knives. A row of small boys feed the spool-making machines by simply placing the blocks in a spout, selecting the best, and throwing out the knotty and defective stock. The machine is automatic, excepting the operation performed by the boys. The strips of white birch as fed into the machine are hardly seen again until the spools, all finished for market except polishing, drop out by the bushel from another machine rods away from where the strips started in. The spools get their gloss by being rapidly revolved in barrels by machinery, the polish resulting from the contact of the spools in the barrel. A peculiar name, either of a locality or a product, always attracts public curiosity, but investigation generally reveals a simple and distinctive origin. No better illustration of this fact can be cited than that of the famous Clark "Mile-End" spool cotton, respecting which many amusing surmises have been made as to the meaning or intent of the word "Mile-End." The name Mile-End was taken from the town near Glasgow, Scotland, where the original spool cotton mills were established, and from which exportations to the United States began in 1820. It was the first thread introduced to the American public on spools, all thread having been previously sold in skeins or hanks. It grew so great in popularity that in 1870 it was deemed advisable to establish a mill in this country, at Newark, N. J., though the name Mile-End has still been maintained.