[f. as prec. + -GRAPH: cf. F. thermographe.]
1. A figure or tracing produced by the action of heat, esp. of the heat-rays of the spectrum upon a prepared surface.
1840. Herschel, in Proc. Roy. Soc., 3 March, 209. He has discovered a process by which the calorific rays in the solar spectrum are made to affect a surface properly prepared … so as to form what may be called a thermograph of the spectrum.
1865. Reader, 28 Jan., 105/2. His drying paper presented to him a thermograph of the spectrum, and showed the heating power to extend far beyond the red.
1871. Tyndall, Fragm. Sc. (1879), I. ii. 48. The light is cut away,… but an invisible thermograph remains.
1906. Athenæum, 23 June, 768/3. Such experiments … will yield valuable ‘thermographs,’ as the resulting parti-coloured ‘prints’ are named.
2. A graphic record of variations of temperature; a heat register; = THERMOGRAM.
1843. Mech. Mag., XXXIX. 128. Obtained … by the aid of the pyrometer,… with the addition of the thermograph, or heat-register, which I have added to it.
1878. T. Bryant, Pract. Surg., I. 55. These points are well seen in the following thermographs.
3. A thermometric instrument which automatically records variations of temperature; a self-registering thermometer.
1881. Nature, 15 Sept., 470/2. Bowkett’s New Thermograph,… an instrument for recording changes of temperature, which are measured by the action of heat upon a hollow circular metallic ring connected with a circular vessel.
1883–4. Med. Ann., 78. Thermograph—an ingenious instrument … for recording in permanent diagrams all variations in temperature occurring in any patient.
