The Sun.
London, England, 1846-12-16 00:00:00

Will the chains which connect the . xles together be
frequently subject to be broken ? In reply to this ques-
tion, it is stated that it is easy to see that the strain
upon them is very trifling, being limited to turning the
crowns, the draught of the train being wholly confined
to the timon and the bsam. At one of the experiments
at St. Maud 4 a chain separated, after which they made
an entire circuit before giving notice to the persons who
conducted the train to stop its progress. This circum-
stance proves that if the whole of the means of direction
be necessary, they can, without serious inconvenience,
be dispensed with upon an intermediate point of the
train. The binding of all the parts of the system keeps
the axle, which may be without a guide, in the regular
route.
As to the essential point—that of overcoming the re-
sistances. When once the train is started, and during
the whole time of its motion, are there, in the proposed
system, causes which might definitely increase their
mean value? If the resistances are diminished in the
curves, are they increased in the straight parts, which
will always be longest ?
It is in regard to the friction of the axles that there
may be an uncertainty.
Now M. Arnoux making the extremities of the axles
bear the weight of the waggons, as is the practice in the
ordinary system, nothing requires him to augment the
diameters of the axles and spindles. He has never-
theless increased the length of the boxes of the inde-
pendent wheels.
"This length," M. Arago says, "is a guarantee against
deviations from the plane in which the :vheels turn." It
does not appear that this plane is less well maintained in
the system where the wheels turn on the axle, than in
that where they are fixed, at least for the time these
wheels last.
The duration of the wheels in the present system is not
great. It is known with what exactitude the wheels fixed
to the axles must be turned in the making. It is known
also with what rapidity the flanges of these wheels are
destroyed by their friction against the sides of the rails
in cases of curves.
In the system of M. Arnoux these resistances disap-
pear ; it gives them a longer duration to the wheels, or
admits of their being made with less perfection and
strength.
In the St. Mattee experiments the wheels were simply
of wood bound with iron ; the edges, instead of forming
one body with fellies, were iron hoops made flat, and
fixed to the body of the wheel by wooden screws.
Notwithstanding, however, the length of curves so
varied, and of so small a radius, in a total circuit of
such great extent, none of the iron hoops, although so
slightly fixed, were torn off, nor did they present any
sensible alteration.
This is another material proof establishing the fact
that the wheels hold perfectly well together, and that
the axles are properly directed.
During these lung experiments there was never felt
in any marked manner those oscillating movements
which are so commonly found in the ordinary railways,
and which are so uncomfortable and so destructive as re-
gards wear and tear.
The only remark which arose when going at the
greatest speed, was relative to the very slight inclina-
tion of the bodies of the carriages proceeding from the
centrifugal force, yet this effect may be lessened by rais-
ing the outer rail.
We now come to the estimate of the total resistances
by the aid of the dynanometer.
These resistances proceed from the current of the
air, from the collision •of the waggons upon the ins•
movable air, from the friction of the axles upon their
periphery, from the rolling of the wheels upon the
rails, from the sliding of their edges upon their sur-
face, from sudden jolts, from the accelerations or
delays in the route of the train, which the best con-
ductors cannot avoid, and of which the influences have
become considerable on account of the magnitude of the
mass in motion. Now all this is susceptible of varia-
tion, according to the tightness of the screws, the
greasing of the boxes, the moisture of the air, and the
greater or less solidity of the rails. As to the last in-
fluence it is real ; for on the journies, the waggons often
make on the sand lying on each side of the rails, figures
of that kind which natural philosophers call acoustic
figures.
Another question. In the system of M. Arnoux is
the resistance perceptibly the same on the straight parts
as on the curves of the railway?
Dynanonsetrical experiments have been made by M.
Morin with a delicate apparatus, which he has greatly
contributed to improve, and with all the care which a
scientific man brings to the estimation of the resistances
he measures.
With wheels not turned the relation which the resist-
ance bore to the charge was found, for the whole of the
road, consisting of straight lines and curves of 50 and
150 metres radius, as also in the small circle of 18 metres
radius, to be the fraction 1-175 ; with wheels turned
the relation descended to 1-204. This relation increased
in an experiment where a guide wheel accidentally
touched the cushions of the rails.
It thence follows that the curves of the road add no-
thing to the resistance, and more than that it shows that
the wheels should be turned, and the guide-wheels ad-
justed with exactitude.
The commission of the Academy determined on corn.
paring this report with that which exists upon the ordi-
nary railroads ; the experiments took place on the Paris
and St. Germain, and the result was found to be 1-200.
"It is necessary to add," said M. Arago, to the advan-
tage of the system of M. Arnoux, that the large spindles
of the axles of all his coaches might have been brought,
without inconvenience to diameters, of 55 millimetres,
instead of 65, and that then, after a co efficient of fric-
tion rather too feeble than too strong, the mean re-
sistance upon the St. Maude road, would be reduced
to 1-230.

Finally, the equality of friction and resistance upon
the curved and straight parts of the railway, when the
coaches are constructed according to the system of M.
Arnou:c, and that the speed does not exceed certain
limits, is completely established by tho experiments at
St. Maude.
These experimmts prove practically that the con•
vergence of the axles is the indispensable condition of a
good service of locomotion, upon the curved rails ; they
prove also that the mechanism of which the projector
makes use, to establish this convergence, has all the pre-
cision that can be desired.

"Thus," adds M. Arago, in terminating his remark.
able report, " the system of M. Arnoux would not im-
pose, so far as one can judge of it, any appreciable in-
crease of expense for traction. With reference to safety,
this system ought to satisfy even the most timid. M.
Arnoux seems then to have completely solved the diffi-
cult problem that has been proposed. Henceforward
engineers will fear less in tracine, railroad lines, to turn
from the direct routes to avoid obstaeles of all kinds,
which, at present, they are obliged to have removed.
The heavy expense of tunnellirg will be less frequently
required ; and finally, by having side rail stations for
passing the roads with a single line of rail, will become
sufficient in many localities where, according to the pre-
sent method, two lines would be absolutely necessary.
" If a long experience of the new coaches does not
produce difficulties, at present unforeseen, the name of
sf. Arnoux will be most honourably placed by the side
of others, who, by their inventions, have rendered great
service to the railways."
This is most flattering approval to an inventor, the
sweetest recompense he can desire for his labours. But
M. Arnoux has found that it is not merely enough to
have merited thes3 praises, for :ince that time he has
been constantly occupied in improving his system, and,
according to the precept of Boileau, he has often turned
to his work for the purpose of polishing and repolishing
it ; we shall state presently the improvements he has
made.

Let us first consider the objections that have been
raised against the system, or against some of its parts.
It has been said, " The great number of pieces of
which the chains are composed render the system liable

to many accidents ;" but the chains have no tension,
since the traction is performed by the timons ; besides,
as we have seen above, a chain has peen detached on
the route, without any harm being done.
It is added that the system is more complicated than
that in common use. To that M. Arnoux replies,
" When it is observed that the main bolts, the crowns,
and the amens are substitutes for the guard plates, the
grease boxes, the buffers, the traction and percussion
springs, and their iron bolts, as well as the braces, and
the connecting chains, it will be found that there is no
comparison to be established either in the number, in the
weight, or in the value cf these essentials ; the error
cannot exist when the actual coaches are seen." Tho
new coaches, in fact, weigh half a ton less than the
others, and cost about 231. less.
It is again said, that the coaches are higher than
those oa the other railways. This is simply a delusion
w hi‘efi an actual survey of them will immediately destroy.
I u
middle tlesef theirr,th length.at the axles
This assertiontheirxlessupportis
charge inndedthe
on facts ; M. Arago laboured, like persons less ac-
quainted with the subject, under this error ; in principle
the charge was supported at 50 centimetres from the
centre of the axles. Since then M. Arnoux has brought
it nearly to the extremities, by increasing the diameter
of the support of the springs.
Again, it is said, that the horizontal movement of the
beds of the carriage experiences a friction equivalent to
that of the flanges of the wheels ; but it is equivalent
oxly in part, since the friction takes place at the entry
and egress of the curves, while in the ordinary system
it exists throughout the whole passage of the train upon

curves.
The only serious and real objection which prevents
the system of M. Arnoux from beinc, geometrically per-
fect is, that the axles take their obliquity a little too
soon, inasmuch as the directing axle the moment it en-
ters the curve forces the second, which is still in the
straight part, to direct itself at right angles to the curve
into which it is about to enter. There, in fact, a resist-
ance is created, which acts during a time, though cer
tainly very short, but which is, nevertheless discernable.
At the egress of the curve the same effect is produced
in an inverse ratio. But to this it may be replied that
the friction lasts but a trifling period, and that it is,
moreover, of that kind which the ordinary waggons
constantly experience in circulating curves.
If a guide wheel were to break would the train be ex-
posed to danger ? In the St. Maude experiments, a
guide wheel was taken off, and the train stopped itself.
But when an axle breaks there is no remedy ; the
breaking of an axle is a very serious accident, that of a
guide wheel much less so.

It is said that neither separate coaches nor the whole
train can be moved backwards. As to the separate
coaches, it is sufficient for the purpose to render the two

* The French word timon is employed for brevity's sake,
instead of inflexible iron rod which colllloo4 the cc c/2" to-
gether, st 4 before atated.