[ 157 ] 
IV. On the Theory of Lubrication and its Application to Mr. Beauchamp Tower’s 
Experiments, including an Experimental Determination of the Viscosity of Olive Oil. 
By Professor Osborne Reynolds, LL.D., F.R.S. 
Received December 29, 1885,—Read February 11, 1886. 
[Plate 8.] 
CONTENTS. 
Section I.—Introductory. 
ARTICLE. 
Discordance of experimental results . . 1 
Mr. Tower’s discovery of the separating film of oil, &c. 2 
The idea of a hydrodynamical theory of lubrication. 3 
The equation of lubrication mentioned before Section A, Montreal, and subsequently 
integrated . 4 
The comparison of the theoretical results with experimental shows a temperature effect 5 
Determination of the variation of viscosity of olive oil brings the theory into complete 
accordance with experiments, and shows how various circumstances affect the 
results........ . . ... 6 
The difference in the radii of brass and journal, and the point of nearest approach of 
brass to journal, and explanation of increased heating on first reversal.. 7 
The limits of complete lubrication, incomplete lubrication, and necking . 7a 
The general arrangement of the paper .... 8 
Section II.—The Properties of Lubricants. 
Definition of viscosity . 9 
The character of viscosity. 10 
The two viscosities. 11 
Experimental determination of the value of for olive oil, &c., figs. 2 and 3, Table I. 12 
The comparative values for ju for different fluids and different units ... 13 
Section III.—General View of the Action of Lubrication. 
The case of two nearly parallel surfaces separated by a viscous fluid..... 14 
The case of revolving cylindrical surface .... 15 
The effect of limited supply of lubricating material. 16 
The relation between resistance, load, and speed for limited lubrication . 17 
The conditions of equilibrium with cylindrical surfaces... 17a 
The wear and heating of bearings .. 18 
