THE VISCOSITY OF WATER. oF 
In this formula L is the length and R the radius of the 
capillary, and T the time taken for volume V of the liquid 
of density 6 to flow through the capillary under a pressure 
gph; nR isa small length of tube producing a loss of 
pressure equivalent to that arising from the friction at the 
ends, its value must be calculated for each series of experi- 
ments; mis the numerical factor in the kinetic energy 
correction, which has a theoretical value of 1°12, but which 
has a practical value which must be determined. The 
factor m has been neglected in so many recent determin- 
ations of viscosity that it is worth the while to repeat the 
information given by Knibbs respecting it. In 1860, Neu- 
mann deduced the value m=1, and Jacobsen used it in his 
‘Introduction to Hemodynamics (1860).’? Hagenbach 
deduced the value m = 1, in the same year. MReynolds 
(following Bernoulli) in 1883, used the value m=4. Couette 
in 1890, independently obtained the value m=1. Boussinesq 
(1891) obtained a more accurate value m=1°12. Garten- 
meister stated (1890) that Finkener had in an unpublished 
treatise shown that Couette’s value was the correct (?) one. 
Wilberforce (1891) pointed out the defect in Hagenbach’s 
reasoning, and he used the value m=1. Knibbs has shewn 
that theoretically Neumann’s correction as deduced by 
Boussinesq is correct, and that experimentally its value 
varies considerably. Knibbs has deduced values of m from 
Jacobsen’s results, and stated that individual results show 
how, even under circumstances in which uniformity might 
be expected, it is not realized; and that if the correction 
be of sensible magnitude, the deduced viscosity is to the 
extent of this uncertainty, unreliable. 
Determination of m and m.—Preliminary experiments 
were made in order to obtain correct (experimental) values 
for the constants m and n. The temperatures were kept 
as close to 50° C. as possible, and under different pressures, 
