92 G. H. KNIBBS. 
Tube. No. Expts. Rapprox.c.m. 7 at 10°C. Authority. 
Glass 8 ‘0877 01323 Jacobson 
5 1147 01334 ” 
Brass Z 1433 ‘01313 ‘y 
Lead 8 3075 01360 Reynolds 
: 8 6350 01365 . 
These results give no indication of slip, for though the final — 
value is somewhat larger than the mean, the difference is infini- 
tesimal in relation to the supposed magnitude of the slip cosfiicient.’ 
It may be remarked that Coulomb’s experiments also appeared 
to indicate an adhesion of the liquids to the submerged oscillating 
discs,’ and that despite considerable alteration in the nature of the 
substances with which they were covered: so also did Meyer's 
But what is more to the point, is that when the motion is 
undoubtedly steady and rectilinear, all experiments by the efflux 
method with glass tubes—and it appears from the above that there — 
is but a doubtful necessity even for this qualification—agreé in 
negativing the idea of slip, not only in the case of water which 
wets the tube, but also in the case of mercury which does not. 
The observations of Warburg,‘ Villari,> and Koch® on the efflux 
of this latter substance, may be taken as determining the question 
of slip in regard thereto in the negative, and a fortiori in the cas? : 
1 Taking the values for tube M and for the largest lead tube, in ordet 
to caleulate the supposed slip, we would obtain for 7, ‘0136 5+ and for 8, 
1 This is sensibly infinite as compared with its value in Helmholtz s. 
remo ih preies to that authority n/B is 03984, whereas 
ly -00000' 
pias in en several values of 7 may be hig On eines” for. 
2 Mém. l'Institut National, t. 3 
a ee die Reibung der eld seks —Pogg. Annal., Bd. 113, P- e 
* Ueber den Ausfluss des Quecksilbers aus gliisernen Capillarrébrea— 
Fogg. Annal. Bd. 140, p. 367 — 379, 1870. 
5 Sull ’efflusso = as per tubi di vetro di —— diametro— 
Mem. dell ’Accad. d. Sci., Bologna, Ser. 3, t. 6, p- 1 
° Ueber die Abhingigkeit der Si abeniante. he  Quecksilbers = 
der Temperatur.—Wied. Annal. Bd. 14, p- 1 - 12, 1881. 
