the Flow of Air through a Pipe. 401 



of measurement diminishes, and since i£ n be taken as 1*26 

 instead of 1'28 the calculated and experimental results are 

 almost in exact coincidence, the results afford a substantial 

 confirmation o£ the validity of the formula. 



Presumably, too, this formula is equally true for the 

 resistance to the flow of any other gas, if the values of c and 

 ]U» for the required gas be used. This still requires experi- 

 mental confirmation. 



Modified Form, of Equation. 

 Formula (4) is, however, very cumbrous, and a preferable 

 formula for practical use would consist of (7') together with 

 a numerical coefficient, the latter taking into account the 

 whole effect of temperature variations. 



Fiff. 2. 



■•w , | L_ 1 1 



i i 









,U- zk^ 





vZ-%-rr 







l0 ° :x ± j - : 



^*** --r-o' 



Nx j 1 



Li-"-'" —--"^'T'-^ 



K^ Ur" 









,.00-5=^^^^^^^ 





1 00 I -CP^S-t^—Ll : . 





^=r i "^f^rn^T-*- 



" ~~~1 "^■ ,T " / Sft 



J^SJ 





1 5*. **. 





•95 U_ _t -£5G 





X^v 



>^ 



! < > 



s. -v >^ 



1 T> 





i 



x ^v h^i> 



•CO 1 .-- 



f\NJ "*& 



1 ■ "" " 



t ^^^ ^ 



i 



> *</* ^ 



1 



5^ S_t 



- 1 



^^v^-^^t 



8- L 



r: _t*i2^ 





"t ^ 







£ H- 





i . IT I _ 





•so! i T ^ II 





30 



GO 



►n s?o ISO 



Temperature ° F. 



!80 



210 



This formula thus becomes 



^,=•000001251^ 



»-i 



/ 



lbs. per sq. in., 



6'(V 4 . d 3 ~ n 



where, in the case of air, K has the values shown graphically 

 in figs. 2 and 3. 



One rather peculiar circumstance becomes evident from 



