LUBRICATION 2*]fl
urveyors of the fatty oik claimed that oils pos*>>*•«!
renter uoiliness," "body" or "lubricating value/' bo! *i.nce
tese claimants seem never to hare ease by the
e-femal measurement of "oiliness" and in<lu>-
cialism requires vastly more oil for p,,*-
ft>ly be met by the available supplies of fatty oik, the ctmi-option
f "the property of oiliness has gradually a sort of will o*
ko wisp vaguely referred to in treatises on lubrication, ami
ively used by energetic salesmen in convincing a
myer of the superiority of a given brand of oil all
Pfcie theory predicted that so long as the viscosity to
*roduce the necessary pressure required to the it
of no moment what the chemical nature of the
3, provided only that the quantity of was
Tltie practice has therefore been to use an oil is
viscous than is really necessary and to a in
in order to insure against any discontinuity in the oil
There are, to be sure, many instances which be
wliere an experienced engineer has a hot by
substituting a fixed oil with which he was for the
oil in use. However, in comparing two oils for
lubrication, there are so many factors which the
comparison such as the quantity of oil, the
ixesrature of the oil film, the condition of the
titia,t instances which might be cited are easily by the
skeptical. Nevertheless, there is a for
cztnts which will be less wasteful of power which at the
s.«tni€ time give the maximum assurance that the not
t>e injured in use. With the aeroplane in it is
s«try to keep the motor going at aU of the
l^exiod of flight, and an overheated may the
oomplete wreckage of the machine in mid-air, so the
of the best lubricant for severe conditions the of
c * oiliness" becomes now vitally important. the
evidence on this point is obtained from cutting
Cuttiag Lubricants.—It is the well-nigh
of mechanicians that in certain cutting oils are
absolutely necessary and that mineral oik wii mot as a
satisfactory substitute. Voluminous