ABSTRACTS 333 



On an Experimental Method of Determining the Relative Effects of 

 Radiation and Convection in Still or Moving Air on the Change in 

 Temperature of a Body in a Given Situation. 



By L. H. Nichols, B.A. 



Presented by A. S. Eve, D.Sc, F.R.S.C. 



(Read May Meeting, 1922) 



Abstract 



This method consists essentially in observing the influence of 

 incident heat radiation and of turbulent atmospheric conditions on 

 the rates of cooling of a pair of large alcohol thermometers (Kata 

 Thermometers^) previously heated above 40°C., one of which has its 

 bulb silvered and polished. 



A preliminary calibration is made by the determination of the 

 rates of cooling of the unsilvered thermometer in a very high vacuum 

 and again in stagnant air when surrounded by enclosures at tempera- 

 tures subsequently required. 



This data, together with records of the rate of cooling of the two 

 thermometers under the conditions to be tested, and the temperature 

 of the air given by a screened thermometer, sufïïce to enable one to 

 determine the relative influence of the main factors, e.g., incident heat 

 radiation and air currents. 



The applications of this method are numerous. In particular it 

 should be possible to allow completely for the influence of solar 

 radiation and atmospheric turbulence upon the readings of various 

 instruments which are at present considered unreliable under 

 open air conditions. The comparative analysis of heating by radiation 

 and heating by convection has important physical bearings and may 

 be facilitated by measurements of this kind. 



As further applications of the method are being developed the 

 completed paper will not be submitted for publication until a later 

 date. 



Many thanks are due to Dr. A. N. Shaw for suggesting the prob- 

 lem and for valuable advice and to Mr. R. J. Clark, B.A.,for invaluable 

 assistance in obtaining high vacua and in the making of apparatus. 



^Hill, Griffith and Flack, "The Measurement of the Rate of Heat-loss at Body 

 Temperatures by Convection, Radiation and Evaporation." Phil. Trans. Roy. 

 Soc, B., Vol. 207, p. 201 (1915). 



