20

FLUIDITY AND PLASTICITY

Using a combination of numerical and graphical methods
following values were obtained.

TABLE VI. — VALUES OF m DEDUCED BY KNIBBS FROM
EXPERIMENTS

Tube
Length in centimeters
Mean radius in centimeters
Values of m

Am ..............
2,55
0.00708
1.04

A™ .....
1 57
0.00708
1.02

Av ........
0.95
0.00708
1.15

AVI .........
0.68
0.00708
1.08

Avn .............
0.10
0.00708
1.12

B ......
10 00
0.00567
1.23

BIV ........
0 90
0.00567
1.14

w ........
0 39
0.00567
1.03

Cv
0 60
0 00427
1 87*

F1
20 00
0 03267
1 08

F11
9 97
0 03267
1.33

F111
5 04
0.03267
1.16

JiIY
2 60
0.03267
0.82*

Fv -
1 07
0 03267
0 82*

The mean is 1.14 or rejecting the values for Cy, F1V, and
1.13. Certain of the tubes, viz., A, A1, A11, B1, B11, B111,
C1, C11, Cm, CT, D, D1, Dn, Dm, D17, E, E1, E11, and F
no satisfactory indication of the value of m. Knibbs dedu.c*o
the value of m from 34 series of experiments made by Jacobso
and obtained an average value of 1.14. This seems like a remould
able justification of the deduction of Boussinesq. But it shou!
be added that the individual values vary from 0.82 to 1.44, yc
perhaps this variation in the values of m should not be ovoi
emphasized since in some instances the amounts of the correctior]
are much smaller than the discrepancies among the observe
tions themselves. Knibbs thinks that the values do vary
than can possibly be accounted for by the experimental error
that possibly the value of m is not a constant for all instruments
It is highly desirable that further experiments be undertaken, t
determine whether m is a constant and equal to 1.12 or if it> j
not constant, the manner of its variation.