152 LAWRENCE R. PROUTY AND JAMES D. HARDY 



thermoelectric thermometry, the reader is referred to the classical 

 papers of W. P. White {15-17). 



Surface Temperatures. One of the most difficult problems from 

 a technical standpoint is that of measuring surface temperatures. 

 The thermocouple is the most widely used thermometer for this 

 purpose. There has been no standard procedure for mounting the 

 thermocouple on the test surface and it has been tacitly assumed 

 that simple contact of the thermocouple wire with the surface to be 

 measured is sufficient. Figure 7 shows several of the methods that 

 have been used for mounting surface thermocouples {18). Other 



TABLE I 



Performance of Various Surface Measuring Devices under Experinaental 

 Conditions (after StoU and Hardy, 18) 



Performance under experimental conditions 



1.500 W. 



lamp 

 Wind loOO W. wind 



Room velocity Infrared lamp velocity 



Instrument (normal) 4 ft. /sec. radiation radiation 2 ft. /sec. 



Dermal radiom- 

 eter Excellent Excellent Excellent Requires Requires 



±0.05 °C. correc- correc- 

 tion tion 



Thermocouple 

 #40 gage wire 

 (bare) Excellent Fair Good Good Excellent 



Thermocouple 

 #28 gage wire 



(bare) Good Fair Poor Poor Poor 



±0.15°C. 



Thermocouple 

 solder bead (ad- 

 hesive tape). . Good Excellent Fair Poor Fair 



Thermocouple 

 #40 gage wire 



(glued) . . . Fair Fair Excellent Fair Fair 



±0.30°C. 



Dermalor resist- 

 ance thermom- 



eter . Fair Good Poor Poor Good 



±0.90°C. 



Pyrometer strip 



thermocouple Very poor Very poor Very poor \ ery poor Very poor 

 ±3.0°C. 



Pyrometer solder ' 



bead Very poor Very poor Very poor Very poor Very poor 



