218 
PROFESSOR O. REYNOLDS ON THE THEORY OF LUBRICATION 
28 per cent, of the friction ; and the values of a, calculated on the assumption of no 
necking, would have to he increased in the ratio n=l'33. 
Even if there is no necking the value of a will probably not be the same ail along 
the journal, in which case the values of a 2 and a in Iv 1 and K 2 will be means, and then 
the square of the mean will be less than the mean of the squares, so that n will probably 
have a value greater than unity, although there may be no necking of the shaft. 
36. A first Approximation to the Difference in the Radii of the Journal and 
Brass No. 1. 
The recorded temperature in Mr. Tower’s Table I. is 90°Fahr. Accepting this, and 
taking the value of p, equation (8), Section II., 
p, 90 =10 6 X 6*81 
. (128) 
By equation (97)— 
4ttN 
Since R=2 and U=-^ 
50 
np — 
a 2-75IUU ' ' 
. ( 129 ) 
np ‘7 2f' 
a~ U 
f 
= 3 ' 46 i • • 
. (189) 
Whence substituting from equation (128) for /x, J0 
-=l(r 6 Xl-97^.(131) 
n J 
and from the tabular Nos. for X/:=100. 
N=100, /=■ 36 "j 
Ci 
-= 10 -4 X 5 ’5 (inch) 
* y .(132) 
N = 480, /=• 89 | 
-= 10~ 4 X 10 (inch) J 
These are the extreme cases ; for intermediate velocities intermediate values of - 
are found. 
