80 



THE ROYAL SOCIETY OF CANADA 



Experiments were also carried out on the cooling of the larger 

 ball from the temperature of red heat downwards. The radiation 

 was measured both by the Light Mill and a Fery Radiation pyro- 

 meter. As timed readings were made alternately on these instru- 

 ments, simultaneous values of their readings had to be made from 

 a time chart. The results are shown in Figs. 4 and 5, where the 

 abscissae are the galvanometer deflections with the Fery instrument 

 and the ordinates are the R.P.M. of the Mill. In Fig. 4 the Mill was 

 placed 50 cms. away from the ball. For fig. 5 at first the Mill was 50 

 cms. away and when it ceased to revolve at this distance it was moved 

 up to 18 cms. distance and when it ceased to revolve at this distance 

 it was moved up to 9 cms. In this way the three graphs AB, CD, 

 EF, were obtained. During this experiment the room temperature 

 was 25°C., and the temperature about one foot away from the ball 

 varied from 36° to 30°C.* 



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3 OS 

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12 76 20 24 28 32 36 



DEFLECTION OF GALVANOMETER OF F£PY RADIOMETER 



4C 



"In the table of Fig. 5 the times 0, .6, 2.0, 4.0 should be .6, 1, 3, 5 respectively. 



