HEAT FROM SMALL CYLINDERS IN A STREAM OF FLUID. 
425 
Description of Table VII.—Effect of Inclination on the Convection Constants of Small Wires. 
In Table VII. is set out the analysis of observations on the effect of inclination on the convection 
constants of one of the wires. The wire was mounted in the fork in such a manner that the end 
connections offered no obstruction to the flow of air, illustrated in (cl) Diagram II. As described in 
Section 14, the previously determined laws of convection were found to hold good ; the values of the 
constants b and 0 were determined in the manner already described, and the variation of the latter with 
the inclination is shown graphically in fig. 8. 
Description of Table VIII.—Analysis of Observations on Free Convection. 
In the accompanying table are set out Langmuir’s ( ! ) observations on the free convection of heat from 
small platinum wires, discussed in terms of the theory of Part I. of the present paper. For the small 
velocities of the free convection current set up by the heated wire this theory affords a rational interpre¬ 
tation of the empirical formula obtained by Langmuir. In heavy-faced type are given the values of the 
heat-losses corrected for radiation; the denominator log (b/a) of formula (75) is set out in italics in the 
following line and is seen to be nearly independent of the temperature, especially for the larger wires; the 
variation of this term with the radius is shown graphically in fig. 9. The use of this diagram, combined 
with formulae (75) and (76), offers a convenient method of roughly estimating the free convection losses 
from small platinum wires. The velocity of the air-flow, which would give rise to the observed heat-loss 
(called the “effective” free convection current), is calculated and is set out in italic characters in the last 
line of the accompanying table. 
(*) Langmuib, 1 Phys. Rev.,’ 34, p. 415, Table VIII., 1912. 
Fig. 8. Effect of inclination on the 
convection constant fi o. 
3 i 
Fig. 9. Variation of log b/a with 
diameter of the wire. 
VOL. CCXIV.-A. 
