ABSTRACTDiffraction gratings are famously associated with Henry Rowland of Johns Hopkins University but there were precursors. Although gratings were first made and used in Europe, reliable machines for ruling gratings were developed in the USA, and two men, Lewis Rutherfurd and William Rogers, tackled the problem before Rowland. Rutherfurd, a wealthy independent astronomer, designed and built the first screw-operated engine for ruling diffraction gratings, the fore-runner of almost all subsequent ruling engines. With it he and his assistant D. C. Chapman (...) ruled many gratings which he generously distributed to practising scientists, thereby materially advancing the science of spectroscopy. Rogers was a Harvard astronomer who developed an interest in the ruling of fine lines on glass that led him to construct a ruling engine with which he investigated the causes of the errors in the rulings he had examined. He continued to seek improvements with a second engine designed for ruling diffraction gratings. He ceased developing this engine when Rowland’s excellent gratings began to be available, concentrating instead on related problems to which he could apply the knowledge and skills he had gained, but his investigations assisted Rowland and other later ruling engine builders. This paper brings together what is known about the ruling engines of Rutherfurd and Rogers, their development, the gratings they produced, their quality and the work that was done with them, and assesses and compares their achievements and the impacts of the work of these two men. (shrink)

SummaryDiffraction gratings have contributed enormously to modern science. Although some historians have written about them, there is much more to be brought to light. This paper discusses their development and use in the period up to about 1880 before Rowland began to produce them. Rittenhouse described the action of a diffraction grating in 1786, but no explanation was possible until the wave theory of light was developed. Fraunhofer discovered the dark lines in the solar spectrum in 1814, and then investigated (...) diffraction, producing the first ruled gratings, making detailed measurements and calculating the wavelengths of prominent spectral lines. After Bunsen and Kirchhoff showed the association between spectral lines and chemical elements there was an upsurge of interest in measuring wavelengths. The gratings used in this work almost all came from one source, a relatively unknown instrument maker called Nobert, who made them by an extremely laborious process using a machine he had built himself. The most significant wavelength measurements were made by Ångström, but Mascart, Van der Willigen, Stefan, Ditscheiner and Cornu also did important work. Nobert gratings were investigated by Quincke, copied photographically by Rayleigh, and were known and discussed in the USA. Nobert's work helped to advance spectroscopy much more than has been acknowledged. (shrink)

ABSTRACT During a visit to Europe in the autumn of 1882, Henry Augustus Rowland, Professor of Physics at Johns Hopkins University, displayed diffraction gratings produced on a ruling engine he had designed and built, which were bigger and much higher quality than any previously made. Some were of a novel type, ruled on concave surfaces, which he used in a simple but equally novel spectroscope that he had devised, to reveal spectral lines in great detail, and by means of photography (...) to record spectral data much more rapidly than previously possible. Over about twenty years Rowland built three ruling engines, published photographic maps of the solar spectrum, compiled a catalogue of the wavelengths of lines in the solar spectrum correlated with laboratory-produced spectra of almost all the chemical elements, and produced and sold the diffraction gratings used by spectroscopists everywhere. For decades after his death Rowland’s ruling engines remained practically the only source of good-quality diffraction gratings. This paper describes and analyses this work of Rowland and of the other men, Theodore Schneider, John Brashear, and Lewis Jewell, who played major roles in it. (shrink)