Parry. — Resistance to Flow of Fluids throngh Pipes. 489 



3. Wood stave pipe under some conditions comes under the definition 

 of smooth pipe, for which 1/C'^ has the value given in paragraph 2 of this 

 summary. 



4. In the present state of knowledge no certainty exists as to the correct 

 expression of the law of resistance to the flow of fluids in rough pipes. 

 Regarding, however, the observations made of the resistance or loss of 

 head in relation to the curve of resistance for smooth pipe, an equation of 

 the same form as for smooth pipe, in which the first expression on the right 

 is constant and of the same value as Professor Lees's equation, viz., — 



•«»°i (s) 



whilst the second term varies with the roughness of the surface, will fit the 

 facts as well as any other, and there are some indications that this is the 

 correct mode of expression. 



5. On the assumption made in paragraph 4, the value of 1/C^ for wood 

 stave pipes lies between 



/ V \ 0"35 

 •00801 ( - j + -000028 



and 



/ V \0-35 



•00801 {-A + -000052, 



whilst the more usual value may be taken as 



/ v\ 0-35 

 •00801 (-^j + -000042. 



6. The value of 1/C^ for riveted pipe lies between 



/ V \0"35 

 -00801 (- j + -000052 



and 



/ V \0-35 



-00801 (- ) + -000098, 

 whilst the more usual value may be taken as 



/ ;.\ 0-3.5 



\ml) 



00801 ( -J + -000068. 



7. For large values of vd/v the value of 1/C^ for any kind of pipe tends 

 towards a constant value and independent of viscosity and therefore of 

 temperature, but varies with the nature of the surface. 



8. For large conduits or canals the same reasoning applies as in the 

 case of large pipes referred to in paragraph 7. 



