Thermodynamic visualisation

This plaster model was made by the great James Clerk Maxwell in 1874 (the photograph was by taken by James Pickands II, 1942). This historic artefact is one of three copies, held in museums around the world, including the Cavendish and the Sloane Physics Laboratory at Yale.

The model shows the relationship between volume, energy, and entropy for a fictitious water-like substance, based on theoretical work by Josiah Willard Gibbs. The lines connect points of equal pressure and of equal temperature. Maxwell found the model a useful aid in his research. The model prefigured modern visualisation techniques – today we would use computer software to visualise such surfaces, like this:

400px-AiryAi_Abs_Surface

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The Double Helix, 60 years later

This photograph (by “Alkivar”) shows a reconstruction of the double helix model of DNA, constructed by James Watson and Francis Crick in 1953. The metal plates are molecular models of bases (some of these plates are original). The model is located in the Science Museum, London (see also their photograph).

This model not only led to one of the greatest-ever breakthroughs in biology (see the original 1953 paper, as PDF), but also demonstrated that “playing with models” was an effective way of doing chemistry. The discovery built on X-ray crystallography work by Maurice Wilkins, Rosalind Franklin, and Raymond Gosling (see their papers and the famous X-ray photograph produced by Gosling). Chemical investigations by Erwin Chargaff and others also produced essential information.

The breakthrough by Watson and Crick is commemorated by, among many other things, the Cambridge stained glass window shown below (located in the dining hall of Gonville and Caius College, photo by “Schutz”).