THE LAW OF RESISTANCE IN PARALLEL CHANNELS. 
971 
Hence putting 
E,= A 
v c L> 
we have 
Again, for tube 5, Table V. 
B c =279‘7 
D="0127 
v c — "2260 
at 8° C. ; at which temperature 
P=-7796 
whence 
B,= 272-0 
The differences in the values of B t . thus obtained would be accounted for by a 
variation of a quarter of a degree in temperature, and hence the results are well 
within the accuracy of the experiments. 
To each critical velocity, of course, there corresponds a critical value of the 
pressure. These are determined as follows. 
The theoretical law of resistance for steady motion may be expressed 
and multiplying both sides by 
D 
P 2 
A c D 2 t=B c Py 
A C T>H 
P 3 
This law holds up to the critical velocity, and then the right hand number is unity 
if B t , has the values just determined. 
P 3 
BH C 
by Table III. 
i c — -0516 
P 2 =-573 
which give 
By Table V. 
which give 
D 3 =-000,000,232 
A c = 47,750,000 
i e = -00638 
P 2 =-607 
D 3 = -00000205 
A c = 46,460,000 
which values of A c differ by less than by what would be caused by half a degree of 
temperature. 
The conclusion, therefore, that the critical velocity would vary as 
L> 
is abundantly verified. 
