Certified Ophthalmic Technician (COT). The Certified Ophthalmic Technician is the second core designation level confirming knowledge in 19 specific content areas specifically designed to test the certified ophthalmic assistant or program graduate who intends to advance their career in the eye care field.
The original spinning jenny used eight spindles instead of the one found on the spinning wheel. A single wheel on the spinning jenny controlled eight spindles, which created a weave using eight threads spun from a corresponding set of rovings. Later models had up to one-hundred and twenty spindles.
Hargreaves' spinning jenny was suited only to spin thread from rovings, while the rovings had to be twisted on the spinning wheel. But the water frame twisted the rovings as well as spun the finished yarn. The water frame thus did away with the spinning wheel in factories, but not with the spinning jenny. The spinning jenny continued to be used to make the softer threads for woof, while the [98] water frame was employed to twist rovings and to spin the harder and stronger yarns.