All of Melloni's activities in the field of heat radiation, from his first speculations on the heat radiated by the sun to his final conclusions on the sameness of radiations, were summarized in his Thermochrôse.
The instrument, signed by its maker at the centre of the graduated rod, most likely was a part of the equipment purchased in 1864 with a special cheque for three thousand lire granted by the Minister at the time when the Physics Laboratory was returned to the university from the Santa Teresa Lycée (now the G. M. Dettori Lycée) where it had been transferred in 1852.