Salts, melting points of, 204. _Seebeck_, discovery of thermo-electricity, 3, 20. _Seger_, pyramids or “cones,” 205. _Siemens_, calorimetric or “water” pyrometer, 201. — indicator for resistance pyrometer, 118. — — — thermo-electric pyrometer, 48. — optical pyrometer, 182. — recorder, 81. — resistance pyrometer, 114. Specific heat of nickel, 197. Standardizing of indicators, 54, 108, 157. Standards of temperature, 9. Steam, measurement of temperature of, 98. _Stefan-Boltzmann_, fourth-power law, 139. _Stone_, pyrometer, 209. Surface temperatures, measurement of, 97. Suspended-coil galvanometers, 45-48. Temperature differences, measurement of, 99. — scales, 7-9. — fixed points of, 16-17. Thermal junctions, changes in, 29. — — choice of metals for, 21. — — E.M.F., developed by, 31. — — methods of joining, 26. — — used in pyrometers, 27. Thermo-electric circuits, 22. — pyrometers, 20. — — calibration curves for, 59. — — for surface temperatures, 97. Thermo-electric circuits, indicators for, 45-53. — — management of, 91. — — practical forms of, 32. — — recorders for, 75-87. — — standardization of, 54. Thermodynamic scale of temperatures, 9. Thermometer, constant volume gas, 11. — mercury, 1. Thermophones, 220. Thread recorder, 78. _Uehling_, pyrometer, 218. Uni-pivot galvanometer, 49. Vapour-pressure pyrometers, 217. _Wanner_, optical pyrometer, 178. Water-cooled cold junction, 33. Water equivalent of calorimeter, 200. “Water” pyrometer, 201. Water-jet pyrometer, 217. _Watkin_, heat recorder, 207. Wedge pyrometer, 190. _Wedgwood_, pyrometer, 211. — test-pieces, 205. _Wheatstone_ bridge for measuring resistance, 104-114. _Whipple_, indicator, 120. _Whipple-Féry_, pyrometer, 154. _Wiborgh_, gas pyrometer, 219. — thermophones, 220. _Wien_, luminosity law, 171. PRINTED IN GREAT BRITAIN BY NEILL AND CO., LTD., EDINBURGH. End of the Project Gutenberg EBook of Pyrometry, by Chas. R. Darling