CONVECTION OF HEAT BY AIR CURRENTS. 



47 



radio-micrometer was removed. Unfortunately, the circuit of the radio-micrometer was 

 so delicately suspended that the vibration of the flooring, owing to the working of the 

 gas engine, caused the spot of light on the scale to oscillate irregularly. I am not 

 prepared to say whether the deflections observed were or were not partially due to a 

 heating of the ball by the current of air. The time at my disposal, being furlough from 

 India, did not allow of further inquiry in this direction. 



I have to acknowledge with many thanks Professor Tait's kindness in allowing me 

 to make use of his laboratory and to draw upon its resources for the purpose of this 

 investigation, and for otherwise assisting me with advice regarding it. I am also 

 indebted to my friend Mr Robert Dickinson for some of the drawings published along 

 with this paper. The Edinburgh University Court sanctioned a grant from the Moray 

 Bequest for the purchase of apparatus required for the work. 



APPENDIX. 



Bates of Cooling {Degrees Centigrade per Minute) at different Temperature Excesses and for different 



Speeds of the Air Current. 



No. of 

 Experiment, 



37 



2 



9 



11 



12 



27 



28 



17 



19 



18 



21 



29 



25 



26 



Speed of 

 Air Current, 



41 



79 



133 



149 



187 



240 



301 



388 



436 



497 



597 



643 



758 



976 



10 



0-47 



0-58 



0-72 



0-71 



0-90 



0-97 



107 



1-20 



1-18 



1-34 



1-37 



1-44 



1-35 



1-80 



20 



0-94 



1-16 



1-44 



1-45 



1-76 



1-83 



2 00 



237 



2-42 



2-82 



2-91 



2-99 



2-87 



362 



30 



1-43 



1-76 



218 



2 23 



2-67 



2-83 



3-11 



351 



3-76 



4-23 



4-45 



4-57 



4-97 



5-40 



40 



193 



2-37 



2-91 



3'04 



353 



3-81 



4-18 



4-71 



515 



5 63 



6-00 



621 



6-69 



7 34 



50 



238 



2-98 



3-68 



3-81 



4-43 



473 



5-20 



602 



6-45 



7-05 



7-63 



7-77 



8-44 



921 



60 



2'98 



359 



4-39 



4-65 



5-29 



5-66 



6-06 



7-29 



7-90 



8-50 



9-21 



934 



10-27 



11-10 



70 



3-58 



4-19 



5-15 



5-44 



6-19 



6-64 



737 



8-65 



931 



9-94 



10-83 



11-07 



11-98 



1295 



80 



4-09 



4-79 



5-89 



6-19 



7-14 



7-63 



8-44 



9-99 



1072 



11-37 



12-24 



12-66 



13-75 



14-77 



90 



4-64 



5-39 



683 



7-01 



7-98 



8-65 



9-56 



11-30 



12-14 



12-86 



14-02 



14-20 



15-68 



1667 



100 



5-22 



5-99 



7-77 



7-91 



8-86 



972 



1069 



12-55 



13-61 



1433 



15-55 



15-81 



17-47 



18-67 



VOL. XL. PART I. (NO. 4). 



