Francis Aston «discovered» the isotopes of the light elements at the Cavendish
Laboratory in 1919 using his newly devised mass-spectrograph. With this device, a modification
of the apparatus he had used as J.J. Thomson’s lab assistant before the war, Aston
was surprised to find that he could elicit isotopes for many of the elements. This work
was contested, but Rutherford, recently appointed to head the Cavendish, was a strong
supporter of Aston’s work, not least because it supported his emergent programme of research
into nuclear structure. This paper will explore Aston’s work in the context of skilled
practice at the Cavendish and in the wider disciplinary contexts of physics and chemistry.
Arguing that Aston’s work was made significant by Rutherford ―and other constituencies,
including chemists and astrophysicists― it will explore the initial construction of isotopes
as scientific objects through their embodiment in material practices. It will also show how
the process of constructing isotopes was retrospectively reified by the award to Aston of
the 1922 Nobel Prize for Chemistry
