¹ This was a consequence of the mathematical devices known as eccentrics, epicycles, and equants. The first referred to a circle whose centre was not the earth, the second a circle whose centre itself moved in a circle, and the third a circular motion appearing uniform from an interior point which was neither its centre nor at the centre of the earth.

² Personal communication.

³ The status of physics was at no time in question. Neither Duhem nor any of the people he discusses applies an instrumentalist theory to all knowledge.

⁴ Paris 10 vols. 1913–59. (As planned, the work had 12 volumes and was never finished.)

⁵ Translation of P. P. Wiener, Princeton 1954. The original French (La theorie physique, son objet et sa structure, Paris 1905 and 1914 is widely available and preferableGoogle Scholar