Thomson was a physicist and engineer who embodied the ‘classical approach’ to physical sciences. His work spanned many areas of the discipline including thermodynamics, electrical theory and practice, navigation and the design and manufacture of precision instruments.

The university holds a number of objects which relate to Kelvin’s early involvement with the transatlantic cables, such as a ‘scalmp’ optical galvanometer, the Kelvin bridge (which he used to demonstrate that early copper cables contained too many impurities for conduction), and a piece of submarine telegraph cable from the 1860-1890 made from copper wire.

In addition, there are several pieces of scientific equipment in the collection relating to Kelvin's investigations into electricity and magnetism. Many of his instruments were made by leading instrument manufacturers but he later went on to set up his own factory with the optical, mathematical and philosophical instrument maker James White, manufacturing instruments to a very high standard. Thomson gave his name to the Kelvin scale which measures temperature to absolute zero.
  
Kelvin's work on calculating the age of the earth based on the rate of the earth’s cooling led him to suggest the earth was 400 million years old. However, he did not account for the effects of radio-active heating from within the earth, as this had yet to be discovered. Kelvin’s estimates of the age of the earth were not old enough to be compatible with Darwin's theory of evolution. This set him at odds with his contemporaries at Aberdeen such as Sir John Struthers and Henry Alleyne Nicholson.

Special Collections Centre holds a section of letters written by Kelvin, discussing time spent with academic collaborators such as the mathematician D. F. Gregory, as well as comments on university life in which he expresses his opinions on funding, staffing and equipment provision.