406 



ME. J. J. MANLEY: OBSEKVATIONS ON THE 



obtained. We were thus led to conclude that a temperature common to the two 

 ends of the beam seldom exists even for a few seconds. The extreme variations in 

 the experiment cited above amounted to almost 1/100 of a degree C. 



(2) We next proceeded to ascertain what the magnitude of the variations in the 

 temperature might be during the time required for loading and unloading the pans. 



The temperature within the case being as nearly as possible normal, the bolometer 

 was read. On lifting the shutter a sudden and marked change in the temperature 

 occurred. Nine weights were then successively placed upon one of the pans, 

 bolometer readings being taken after the introduction of each weight. Lastly, the 

 weights were removed one by one, and bolometer readings taken after the withdrawal 

 of each. All the readings were then reduced, as in the preceding experiment, to their 

 equivalent temperature values, and the results plotted in a corresponding manner. 



The observed temperature changes occurring during one of a number of experiments 

 are shown graphically in Fig. IX. 



X 



c 



0230 

 0280 





After 

 adding 



50 20 10' 10" 5 Z ( l" \ l."'qrms. 



Door open. 



,e---^ 



After removing 5,0 2,0 1,0' i.o" 521,' /," 



Door CioAed. 



Time in Seconds 



IS JO 45 60 75 90 105 120 I3S ISO I6S IOO IS5 



.-O2SO 



oaoo 

 oiao 



0/60 

 014-0 

 .0120 

 :OIOO 



ooao 



.0060 



OO40 



:002O 



.2O-OOOO 



9930 



9960 



99*O 



9920. 



225 Z4O 255 27O 285 300 



We observe that in this particular experiment the extreme difference in the 

 temperature of the air in the vicinity of the ends of the beam was approximately 

 0- 025 C. But it was found that the larger disturbances just recorded gave place 

 within a few minutes after the conclusion of the experiment, to the usual and much 

 smaller ones ; the mean temperature was, however, a little higher than at first. The 

 slight increase in the temperature during the experiment is indicated by the general 

 up-treud of the curve. 



