Robert Reid reports.
One of the most delicate jobs a scientist can tackle is the making of diffraction gratings-a number of extremely fine lines ruled on pieces of glass-up to 30,000 of them to an inch. These can be used for very accurate measurement. Dr. Sayce, of the National Physical Laboratory, tells the story of how an inexpensive method has been developed to produce these gratings and how their use may ultimately lead to a revolution in engineering and industry.