Jedlik's aim was therefore not to increase the number of lines, but to make the spacing of the scratches even.  By 1860 he had a machine that worked accurately. It took about 10 seconds to draw a line, after which the needle would rise and the machine would push the point corresponding to the end of the next line under the needle. It took several days to complete a single grid - 12 000 lines - so he used another of his inventions, the electric motor, to drive the machine. The machine worked automatically, powered by electric motor. He made several types of grids: linear, cross and circular. The production of the grids required a great deal of chemical knowledge and experimentation (the glass was fine-coated, scratched and the scratched surface etched) until Jedlik found the most suitable materials. His excellent optical gratings became known and sought after. An optician in Paris, from whom Jedlik had once bought a clockwork arc lamp, became the main distributor. Jedlik's gratings won the respect of experts for their precision and high brightness. They helped to achieve a wavelength resolution of the spectrum below nanometres (10–9 m). Its optical gratings, with more than 2,000 lines per millimetre, were still used for spectroscopy even in the 1960s.