AND ITS APPLICATION TO MR. B. TOWER’S EXPERIMENTS. 
217 
n is a coefficient depending on the way in which the journal fits the shaft. 
>-.(124) 
T , U x 60 
* — — A-HT 
8 = 1-21 
-J 
L' = 
f'= 
JL 
4s 
nM 
4R 
35. The Effect of Necking the Journal. 
The expression (124) for f assumes that the journal was not necked into the shaft. 
From Mr. Tower’s reports it does not appear whether or not the brass was fitted into 
a neck on the shaft; but since there is no mention of such necking, the theory is 
applied on the supposition that there was not. 
If there were, the friction at the ends of the brass would increase the moment of 
friction. Put b for the depth of the neck and a' for the thickness of the oil film at 
the ends, then the moment of resistance of these ends would be— 
s-x £(»+§>* 
Hence if M be the moment of friction of the cylindrical portion of the journal only 
f 8 ( B +§)’= 6 f 
(125) 
And from equation (97)— 
,_^ M r +I ) 3 
^ 3(50 a «/R 
1 
+ 8-25R 2 !» 
J 
. . (126) 
For example, a 5-inch shaft necked down to a 4-inch journal would give b —'5 inch. 
Whence, assuming 
a!= *0005 "j 
and I 
) ......... (120 
-,= 2 
J 
the relative friction of the ends to that of the journal would be 11’36 to 31'00, or 
MDCCCLXXXVI. 2 F 
