When instruments disappear from view

No investigator did more to popularize the idealization of instruments and experimental conditions than Bessel. In addition to numerous applications of and elaborations upon the method of least squares, Bessel contributed significantly to the theory of astronomical and related instruments. Wanting to assemble a fixed star catalogue based on James Bradley's observations from 1750-1762, Bessel found he needed an alternative theory of refraction in order to refine Bradley's data.

La mesure du temps et de l'espace au XVIIe siècle

Il a fallu attendre le milieu du XVIIe siècle pour voir Henry Moore et Isaac Barrow définir le temps d’une façon utilisable par les physiciens. C’est seulement alors que les plus grands savants de l’époque parvinrent à élaborer des méthodes de mesure précises du temps et de l’espace. Comme le dit A. Koyré : « Les raisons de construire des instruments corrects pour mesurer le temps étaient, et sont encore immanentes au développement scientifique lui-même ». La même remarque s’applique à la mesure de l’espace. 


George Graham

"Born in the parish of Kirklinton, Cumberland, July 7, 1673, of parents who were members of the Society of Friends. In 1688, he came to London, and was apprenticed to Henry Aske, Clockmaker, July 2 in that year. During his apprenticeship he made the acquaintance of the family of the celebrated Thomas Tompios, Watchmaker, of Fleet Street, who ultimately received him into his employ. He married Elizabeth the daughter of Tompion's brother James, and at his master's decease in November, 1713, succeeded to the business.

George Graham, Maker of Horological and Astronomical Instruments

His life (George Graham's) is of particular interest to astronomers because of the part he played in the progress of their science. Although, by 1700, the telescope had increased astronomical knowledge by many discoveries, it was obvious that more accurate instruments had to be devised before further advance could be attained. Necessary mechanical improvements were furnished by George Graham ans others of his time.