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F. Darton and Co of 142 St. John Street and 52 Clerkenwell Road, London, EC
1834 Company established.
1904-06 Producing small gas and oil engines at 1/3rd hp. 
1914 Wholesale manufacturing opticians and scientific instrument makers. Specialities: standard meteorological instruments for observatories, recording meteorological instruments, spectacles and folders, opera, field and marine glasses, prism binoculars, microscopes and telescopes, meteorological instruments, barometers and thermometers, clinical etc., electro-medical apparatus, electrical accessories, model motors and dynamos etc. 
c1930s F. Darton and Co Ltd., of Yale Road, Bushey, Watford, Herts - makers of anemometers, barometers, barographs, hygrometers, hygrographs, rain gauges, recording rain gauges, record charts, recording ink nibs etc., school equipment, thermometers, thermometer screens, thermographs.