Convection of Heat from a Body cooled by Stream of Fluid. 591 



and (c) in which the charge on a Faraday cylinder leaks 

 away when care is taken to prevent free ions reaching it, 

 seem to indicate that neutral doublets as well as free ions are 

 ejected from the salt. 



In conclusion, I should like to thank Dr. R. S. Willows, 

 in whose laboratory these experiments have been carried out, 

 for the interest he has taken throughout the course of this 

 research, and Mr. F. C. G. Bratt for help in the construction 

 of the apparatus used. 



Cass Technical Institute, 



Jewry Street, E.C. 



May 1910. 



LXII. The Convection of Heat from a Body cooled by a 

 Stream of Fluid. By Alexander Russell, M.A., B.Sc, 

 M.I.E.E., Principal of Faraday House *. 



Table of Contents. 



1. Introduction. 



2. Historical. 



3. The assumptions made. 



4. Flow in two dimensions, 

 o. Circular cylinder. 



6. Cylinder with elliptic section. 



7. Flat strip. 



8. Cylindrical tube. 



9. Tables of the values of the function Z/X. 



10. Simplified formula for cylindrical tube. 



11. Turbulent flow. 



12. Electric current required to fuse a wire. 

 18. Schwartz's experimental results. 



14. Steady temperature of a wire carrying an electric current. 



15. The effect on the convection of heat from a cylinder of 



putting a covering round it. 



1. Introduction. 



THE phenomenon of the convection of heat at the surface 

 of a body immersed in a cooling fluid is one which does 

 not lend itself readily to mathematical calculation. If the 

 fluid be a gas the variations of the pressure, density, and 

 velocity at different points of the gas so complicate the 

 problem that little progress towards a complete solution has 

 yet been made. In the case of liquids flowing past a body 

 with appreciable but not excessive velocity, Boussinesq f has 



* Communicated by the Physical Society : read July 8, 1910. 

 t Theorie Analytique de la Chaleur, t. ii. 1903, and Journal de Mathe- 

 matiques, 6 e Serie, t. i. (1905). 



