334 



Mr. A. H. Davis on Natural 



Calculation from these data yields the values for k and v 

 Table II. 



given in Table II. 



°c. 



Air. 



Hydrogen. 



Oxygen . 



10 4 .&. 



v. 



10* . k. 



V. 



10 4 . k. 



V. 







0-55 



013 



3-7 



0-9 



0-58 



•14 



17 



0-58 



0-15 



4-1 



1-1 



0'61 



•15 



100 



0-72 



023 



4-7 



1-6 



075 



•24 



200 



0-86 



0-35 



5-7 



2-4 



0-91 



•36 



300 



101 



0-48 



65 



33 



1-00 



•50 



400 



1-14 



0-62 



7-4 



4-2 



120 



•66 



500 



1-27 



0-78 



82 



5-3 



1-33 



•83 



1000 



1-89 



1-76 



11*8 



11-4 



1-97 



1-85 



(4) Summary of collected data. 



Following the procedure explained, Tables III. and IV. 

 have been compiled summarizing a wide range of data for 

 convection losses from cylinders. In the experiments of 

 Table III. the wires were used mainly in free air, or in 

 enclosures so large that the free air figure would evidently 

 be obtained. It appears, however, that heat losses from 

 wires in even a small enclosure (a few centimetres diameter) 

 are not different from those obtained in an unlimited medium. 

 In Table III. the results by Ayrton and Kilgour were 

 obtained using water-cooled enclosures 5 '08 cm. internal 

 diameter, and they agree excellently with data for similar 

 wires in practically free air, as given by Langmuir and 

 by Kennelly. Table IV. refers to an enclosure of 2*06 cm. 

 diameter, and this is still fairly large compared with the 

 diameter of the wire, and the results for air at one atmo- 

 sphere agree satisfactorily with the curve derived from data 

 for free air already considered. Results given in the tables 

 are plotted in fig. 1. 



The sources from which the summary was compiled are 

 briefly indicated below, the distinguishing letters corre- 

 sponding with those used in the tables : — 



(A) Langmuir * conducted experiments practicallv in free 



* Langmuir, loc. cit. 



