The present book was written for three classes of readers-"college students, technically trained men who deal with processes requiring high temperature measurements, and less trained observers who may make the measurements." The book is practically a synopsis of "Measurement of high temperatures" by Burgess and Le Chatelier, Wiley, 1912, but is presented in different form especially suitable for the class room, as minor details are omitted, and in several places the text is illustrated by practical problems. Also at the end of each chapter are several experiments, fourteen in all, which are prepared in sufficient detail for the ordinary student, and which cover the field of pyrometry very satisfactorily. The chapters are headed as follows: (1) Standard Temperature Scales; (2) Resistance Pyrometry; (3) Thermoelectric Pyrometry; (4) Radiation Pyrometry; (5) Optical Pyrometry. The text is well illustrated and several new American instruments are shown. A few comments may be made on points of minor detail. In the preface it is stated that "the day is already past when foundrymen and steel workers depend upon the eye to judge the temperatures of their product in the various stages of its heat treatment, when makers of ceramic products depend upon the indication of fusible cones," etc. One needs but visit industrial plants to realize this Utopian condition is far from being fulfilled. Probably nine out of ten ceramic industries employ fusible cones or similar means of temperature measurement, and many of the leading ceramic engineers of this country advocate their use in preference to more scientific instruments. A point in history is brought out on page 3. Bolton ("Evolution of the thermometer") states that Celsius assigned the number 100 to the temperature of melting ice and o to the temperature of steam. The present assignment of numerals was made by Christ in 1743. Also, according to Bolton, Fahrenheit did not assign the number 212 to the boiling point of water as here stated. The method of correcting for lead resistance of the resistance thermometer, page 21, is crude. Even for the most elementary students, the bridge should be arranged as in Fig. 7. A student will be interested in solving the mathematics of the Wheatstone bridge in order to see why the arrangement in Fig. 7 compensates properly. Sulphur should not be boiled in an aluminum tube as illustrated in Fig. 15. With such a tube electrically heated to the top as shown in the figure, the vapor can be superheated to almost any value. The heating coil should be much shorter, and for accurate work glass tubes are to be preferred. The geometrical optics of Fig. 44 is incorrect. Prism M, Fig. 62, should be turned through 1800. Recent work indicates that C2 is more nearly equal to 14,350 than 14,500 as given on page 91. On page 140 it is stated that "a person of no training can get better results with a radiation pyrometer than with an optical pyrometer." This is contrary to experience. Published investigation has shown that persons who are totally unfamiliar with the optical pyrometer can set to within 50 or 10° C. To obtain such accuracy with a radiation pyrometer requires a great amount of experience and a consideration of many factors which are not mentioned in any text-book.... The demand for engineers having some knowledge of practical pyrometry is becoming greater every year. Many schools are offering courses in this subject and the day is near when pyrometry will be a required course for engineers and chemists. The present book should serve as a suitable text for a junior or senior course covering one semester. -Physical Review [1918]