54 R. HOSKING. 
in Figure 5 (Plate 8) indicate that when the change takes 
place, there is a large increase in the value of m, if the 
formula still holds; but the individual results do not agree 
sufficiently well to enable one to draw definite conclusions 
from them. The values for the viscosity of water at 50° 
C., obtained with the various capillary tubes in the glis- 
chrometer are collected in the foregoing table. The mean 
value is ‘00550. 
Results.— 
(1) The constants in the reduction formula were all 
determined with the greatest possible degree of accuracy, 
including R, n and m. 
(2) For each capillary in the glischrometer—four were 
used separately—two values for m were found, one for 
each of the ends. These values were in every case greater 
than the theoretical value 1°12. | 
' (3) For the series of capillary tubes used, experiments 
at temperatures 0° O., 25° C., and 50° C. gave in each case 
zero values for n. 
(4) Absolute values for the viscosity of water at 0° C., 
25° O., and 50° ©. were obtained, namely ‘01793, °00893, 
and °00550, which are probably correct to 0°1 per cent. 
(5) The values obtained for m were constant over a big 
range of pressure; and at a very high pressure there was 
an indication of an abrupt change in the value of m, or in 
the nature of the flow. The velocities at this pressure 
were much below the critical velocities for the various 
tubes, but were all above the lower limit of critical 
velocity. 
(6) Consistent values for the viscosity of water at 50° C. 
were obtained in cases where the kinetic energy correction 
was as high as 60 per cent. of the viscosity. 
I have much pleasure in acknowledging my indebtedness 
to Professor J. J. Thomson, Cavendish Laboratory, Cam- 
