The Washington herald., 1908-02-16

That the 'side-slip." usually feared by
automobilists as a danger, is really a
means OF protection. enabling motor cars
10 take corners at speeds that would
otherwise overturu them, Is asserted by a
French mechanician, George Marie ac-
cording 10 the Literary Digest The side
slip in such a case. We are told. takes
up the energy that would otherwise ex-
pend itself in lifting up the heavy car
and capsizing il. Says Paris Cosmos IN
"A notice Of Marie's Investigations
"Benehcent skidding, Do not wonder
at this exclamation. much as il may diff
fer from the customary view Of an occur
renee that has caused so many automo-
bile accidents / am certainly not ign0T-
ant of the fact that many automobiles
that have skidded, either because of too
sudden braking or simply from encoun-
tering a slippery pavement. have been
so unfortunate as to upset, hurling their
passengers to the ground or against
trees. These are the regTettabIa results
Of skidding And nevertheless we need
not object too strenuously to it; Ike
salt. it is good in moderation. Chauf-
feurs are under great obligation to skid
ding, which is, says George Marie, the
safety-valve OF automObiling.
Mr. Marie has presented to- the So
ciety of civil engineers some noteworthy
memoirs treating of the question of os-
cillation in railway trains on entering
and leaving a curve, and he has endeav-
ored to fix the conditions that must be
satisfied by the track and rolling stock,
that these oscillations may be dampened
and limited to an amplitude within the
danger of derailment For automobiles
there is no danger of leaving the track,
/ but great danger Of overturning, and
with some notifications Maries conclu-
sions about trains apply also to autOmO-
/ bles. Now the author shows that chauf-
/ feurs, even the most prudent. often take
curves with Tadii Of curvature much
smaller than would suffice to oyerturn
railway car other things being equal
| If the wheels were guided and held by
rails, there would certainly be an accl-
dent what saves the chauffeur and his
vehicle is the lateral skidding that re-
/ establishes the equilibrium endangered
by centrifugal force.
Again, the lateral sliding has a power
| full protective effect even when it is too
| slight to show on the track Marie shows
| that In practice the wheel-marks are
| broadened only eight millimeters lone
| third of an inch) for a centrifugal force
/ double that which would Oyerturn a rail
way car under the same conditions.
when there is no sidewise motion
/ for whatever cause, at the moment ol
| taking a sharp curve, the car runs rea
danger The impOssbility of such motion
| is encountered in two practical cases
! First we have the bursting OF a tire dur
| ing a sudden tuTn-no imaginary case
since such turns impose on the tire a
transverse strain that it is i'll prepared tC
| support-when the iron rim strikes this
road and prevents all lateral motOF
] Secondly, there is the case of an auto
mobile that turns suddenly on striking
| a soft, sandy road.
"A rut in the road, a high tramway
rail, or in general any momentary obsta-
Gle to lateral slipping is a cause of dan.
ger, but less grave than the preceding
/ The car, indeed, tends to upset. but if tho
obstacle is quickly passed il will not have
time to do so.
"A turn of 10 meters (33 feeO radius is
generally to be made only in an emer
gency. to avoid running over some one
for instance. If the wheels are IA meters
(55 inches) apart and the center of gravity
09 meter (35 inches) ABOVE the ground
calculation shows that an upset would
take place in this case with speed o.