VISCOSITY OF WATER BY THE EFFLUX METHOD. 83 
1860 to a meeting of physicists at Kénigsberg, and in this the 
results of measurements of efflux for temperatures up to 71°5 a 
were given. 
Magnus? experiments in 1850 and 1855 should perhaps have 
been mentioned as affording physical illustrations of viscosity ; 
they contributed however nothing of moment in regard to its 
numerical evaluation. At this period the general significance 
and importance of the viscous property of fluids was forcing itself 
strongly upon the attention of physicists, particularly perhaps in 
the direction of chemical physics, and in 1861 Graham’s* essay 
appeared “On liquid transpiration in regard to chemical compo- 
sition,” an early contribution in that department of research. 
Graham’s work is of interest to our present purpose mainly 
because in his measurements of flow through capillary tubes he 
also greatly extended the range of temperature beyond Poiseuille’s 
limits, carrying it as far as 70° C.—i.e. 25° beyond Poiseuille— 
and also because he made measurements for every degree up to 5°. 
Had his experiments been more accurate they would have afforded 
an opportunity of examining whether the mathematical expression 
of the law of viscosity showed any peculiarity at the temperature 
of maximum density. 
a the same year (1861) Meyer's’ first contribution to the theory 
: of internal flnid friction, and to experimental research therein, 
Was published. Seven years later (1868) at Bonn, Rellstab’s* 
dissertation on the transpiration of similar fluids traversed the 
subj 
oa ject, and gave also the results of some new measurements by 
i ee 
1 
- ong die Bewegung der Fliissigkeiten.—Pogg. Annal. Bd. 89, p 
ca "§ eg Hydraulische Untersuchungen.—Pogg. Annal. on i 
OD. 
a 
: gem Roy. Soc. Lond., Vol. 151, p. 373 - 886, 1861. 
e ‘sie die Reibung fed siovear ets (Theoretischer Teil). —Crelle 
é ‘s ay h. Bd. 59, p 1861, and ee title, Pogg. Annal. Bd. 
tu 86, ie: oo are 383 - 245, 
ber die ce homologer eg —tnaagucadioser 
ah 
