SCIENCE. 
155 
oval, not an ellipse; a new illustration, in Dr. Hill’s opin- 
ion, of the fact that the ability of members of two groups of 
forms to assume an intermediate form affords but a very 
slight presumption, if any, for a community of origin in the 
group. 
FRICTION OF LUBRICATING OILS. 
By C. J. 'H. Woodbury. 
The resistance existing between bodies of fixed matter 
moving with different velocities or directions presents itself 
in the form of a passive force, which results in the diminu- 
tion or destruction of opponent motion. Modern science 
has demonstrated that this destruction is only apparent, 
being merely the conversion of the force of the moving 
body into the oscillation of the resisting obstacle or into that 
molecular vibration which is recognized as heat. Direct 
friction refers to the case where the two bodies are in actual 
contact and mediate friction where a film of lubricant is in- 
terposed between the surfaces, and it is this which applies 
to nearly every motion in mechanics where bodies slide 
upon each other. The coefficient of friction is the relation 
which the pressure upon moving surfaces bears to resist- 
ance. Mr. Woodbury limited his discussion to a descrip- 
tion of the apparatus for measuring the friction of lubrica- 
ting oils, the method of its use and the results obtained 
with a number of oils in the market which are used for 
lubricating spindles. Previous investigation of nine 
different oil-testing machines used showed that none 
of them could yield consistent duplicate results in fur- 
nishing the co-efficient of friction. The paper mentioned 
the circumstances which must be known or preserved 
constant, — temperature, velocity, pressure, area of frictional 
surfaces, thickness of the film of oil between the surfaces, 
and the mechanical effect of the friction. The radiation of 
heat generated by friction must be reduced to a minimum, 
and no oil should be allowed to escape till subjected to 
attrition. Therefore a dynamometer is required which is 
instantaneous and automatic in its action. Mr. Woodbury 
described in detail the construction of his instrument and 
the mode of its operation, which was too elaborate to be 
reproduced in an abstract. The operation of the machine 
under equal conditions with the same oil gives results 
which are as closely consistent with each other as could be 
expected from such physical measurements. Much of the 
slight irregularity was due to the variable speed of the en- 
gine. The results were remarkably uniform, but they do 
not agree with the laws of friction, as given in works on 
mechanics, but the co-efficient of friction varies in an in- 
verse ratio with the pressure. Friction varies as the area, 
because the adhesiveness of the lubricant is proportional 
to the area, and the resistance due to this cause is a larger 
fraction of the total mechanical effect with light than with 
heavy pressures. The lubricant used is one of the most 
important factors in the cost of power. In the present con- 
dition of engineering science it is impossible to state what 
exact proportion of the power used by a mill is lost in 
sliding friction, but in a print-cloth mill only about 25 per 
cent, of the power is utilized in the actual processes of 
carding, spinning and weaving the fibre, not including the 
machinery engaged in the operation, leaving 75 per cent, of 
the power as absorbed by the rigidity of the belts, the re- 
sistance of the air and friction. Mr. Woodbury concludes 
that the successful operation of a spinning frame is far 
more closely dependent upon the individual management 
in respect to the conditions of band-tension, lubrication 
and temperature of the spinning room than all other causes 
combined. Not that some forms of spindle are not supe- 
rior to others, but without vise supervision the most desir- 
able forms of spindle must fail to show the merits due to 
the skill of their promoter. The lubricating qualities of an 
oil are inversely proportional to its viscosity ; the endurance 
of a lubricant is, in some degree, proportional to its adhe- 
sion to the surfaces forming th ■; journal. An ideal lubri- 
cant, in these respects, would b^ a fluid whose molecules 
had a minimum cohesion for each other, and a maximum 
adhesion for metallic surfaces. Viscous oils adhere more 
strongly to metal surfaces, hence it is obligatory to use such 
thick lubricants on heavy bearings. With light pressures 
more fluid oils are admissable, and in all cases the oils 
should be as limpid as possible. Oils with great endurance 
are likely to give great fractional resistance, and in the en- 
deavor to save gallons of oil, many a manager has wasted 
tons of coal. The true solution of the problem of lubrica- 
ting machinery is to ascertain the consumption of oil and 
the expenditure of power, both being measured by the same 
unit, namely, dollars. Mr. Woodbury detailed his experi- 
ments in measuring the fluidity of oils, and gave the data 
for determining the safety and efficiency of a lubricant. 
THE LAW OF LAND-FORMING ON OUR 
GLOBE. 
By Prof. Richard Owen, M.D., LL.D.* 
The truth of a general law can best be proved by such a 
large collection of co-incident facts as to carry conviction to 
the scientist. But in a synopsis all that can be done is to 
state the law and suggest a few prominent demonstrations, 
leaving it for the reader to trace with compasses or string, 
on a good globe or large map of each separate continent, 
those phenomena presented, and such other analogous de- 
tails as may suggest themselves. 
General Law: The land shows itself above the ocean level , 
in definite multiple proportions , by measurement; the unit is 
the angular difference between the axis of revolution and the 
axis of progression. 
For convenience, as that angle has been lessening for 
some centuries, we might call it 24°= a j fi 5 a °. 
The greatest width and length of continents =3X24°=72° 
— 1S.Q.° 
6 
Consequently, the radius for continents=36°= a , fi 0 a °. 
The measure for oceanic distances is the complement of 
24°=: 66°. 
The ratio of land to water is as 100 : 275. 
The ratio of 24 0 to 66° :: 100 : 275. 
All measurements are to be estimated at the equator. 
The above general law may, for the purpose of demon- 
stration, be subdivided. 
I. — First subdivision or section of the law. — Many longi- 
tudinal elevations and depressions on the earth’s surface, 
especially near the greatest median, north and south, ex- 
tension of each continent, coincide with some meridian. 
Although this is partly due to early cooling and shrinkage, 
probably all continents have been extended north and 
south by successive depositions, as great river-deltas are 
usually found near the southern terminus of that median 
line. On these median lines we seldom find volcanoes. 
Demonstration. — As the details regarding North America 
are most familiar, illustrations will be taken chiefly from 
that continent, although the law applies as well to all the 
others. In North America the greatest elongation is about 
in long. 96° W. of Gr. Near that line, as we shall see later, 
are found the foci of land forming for our continent, and 
not far distant the great rivers which drain the Mississippi 
valley. From Boothia Felix to the Gulf of Mexico we have 
no volcanoes, and the only earthquake action (near New 
Madrid, etc.) is due to a great circle of force crossing diag- 
onally as shown subsequently. 
II. — Second Subdivision of the Law. — Although the median 
lines of continents run north and south, the outlines or 
trends of continents form, with the meridians, angles of 
about 23 Yf (as I pointed out in “ Key to the Geology of the 
* Former State Geologist of Indiana, and for fifteen years Professor of 
Natural Science in the Indiana State University. 
