An International Correspondence Schools instruction paper describing the construction, operation, setting and management of the cotton spooler, the machine that winds yarn from spinning-frame bobbins onto spools for the next process. It covers bobbin holders, thread guides, spools and spindles, spindle banding, mangle-gear builder motions, settings and adjustments, and common faults. Worked calculations for spindle speed, change gears and production are included, followed by examination questions for students.