The morning news. [volume] (Savannah, Ga.) 1887-1900, 1896-10-12
PNEUMATIC TIRES.

Experiments Show Their Great Adj
vantage over the Solid Cushion.
From the New York Evening Telegram.
Just why a pneumatic tire lessons the
work of propelling a bicycle has been a
mystery All wheelmen have believed that
they know all about it, hut the scientists
have been puzzledy for they could not find
a real reason for it. But now it is known
definitely just where the advantage lies,
and the locating of II develops some Gu,
rious features.
A great many American wheelmen VINO
have given the subject a good deal OF
thought, have watched with eager inter
est the experiments Just completed by NJ
A. ]. Michelin of the Society of France,
by which he has cleared up this puzzdlng
problem. These experiments were made
with great thoroughness and included five
series of tests with the pneumatic tire
and the ordinary wheel They took place
when the ground was covered with mud
Of different degrees of depth and consist
ency.
NJ. Michelin has proven that with an
empty vehicle moving at a walking pace
through deep. soft mud the draugllt was
about thirty-five pounds with the iron
wheel and but twenty-five with the pneu-
matte tire. With thick, sticky mud on
the road, under the same conditions of
load and speed, the pulls were fifty pounds
for the iron wheel and thirty-one for the
pneumatic tire The other tests consist
ed Of pulls of varying speed over macad-
am paved and ordinary roads, and in
every instance the pneumatic tire showed
a saving in pulling power Of from 80 10
so per cent.
The explanation of all this is really sim
pie. A pneumatic tire runs easier than
a solid cushion, because 1t practically
levels the track upon which the wheal
runs. Even when in good condition, roads
are scarcely ever free from dust, and the
solid cushion tire, being of small diameter
and rather hard, will bear upon but a
small surIec e of the dust, and, therefore,
will compress it considerably. The rup,'
Der, beins hard, a considerable amount
of force is required to fatten 1t out at
the front az the wheel moves along. The
result Of this is to make the actual pain
of the wheel up grade, even though the
road Itself may be level.
Under the same conditions, the pneu-
matte tire, being much more yielding than
the solid cushion will hatten out and
cover more surface. AS the surface COW
cred is greater, the compression of the
dust will naturally be less. From this
fact alone 1t is easy to see that the pneu-
matte tire will run easier on a soft
road or on a hard road covered with a
thick layer of dust, because as the wheel
does not sink so Deep It does not have
to climb so steep a grade at the front
of the rut.
On a perfectly clean and hard road the
force lost in COMPRISING the hard rub
her of ~the cushion tire is saved, and
the elasticity of the pneumatic tire makes
the force necessary to compress the front
of the tire almost imperceptible.
On a perfectly clean and hard road
when riding at a slow rate Of speed, there
is hardly any difference in the amount
OF power required to propel a wheel
whether It has solid or pneumatic tire
but as soon as the velocity is increased
the power to move the solid tired wheel
must be increased In a greater proper
tion than the power necessary to force
the pneumatic tired machine at the same
rate of speed, as in the latter the force
necessary to compress the front Of the
tire is hardly noticeable. About the only
resistance which is offered at such times
is the friction Of the machine itself The
resistance Of the cushion tire under the
same condition is not only the friction
of the machine, but also the resistance
Of the tire itself.