The Manchester journal. [volume] (Manchester, Vt.) 1861-current, 1913-02-06

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AN oiLrp sAnAnkn HoAp WITH xAcuGsf
TRAVELLING sl1rF MiLIa rEh houk-so
DUST
Chimes owned IN the United States, and
the number Is increasing at marvel
Gus rate
The fact that must give Us concern
IL that the old methods Of construction
which have stood every test for more
than 100 years are inadequate TO meet
The conditions Of this new form Of traf
DC and that We are 10 the midst OF
transition period which must eventual
b Fpvoluii0nire the science and an Of
tue road builder. The highway en-
yineer Of today is called upon TO ascer
tain In whit way the automobile in
lures the road what Is the exact cause
of the injury. and nnaily to devise an
adequate remedy.
When TresagueL the great French
engineer, made bis report TO the cuun
"a OF bridges and roads In 1915 he sci
forth the principles Of constructio.
which. Bs modified and added to BY
John l.. Macadam In the early part OF
the nineteenth century, have proved
adequate until the twentieth century
These great road builders aud their
Successors sought 10 secure road ca
pable Of withstanding the wear of iron
tired horse drawn vehicles. for the mo
tor driven vehicles had no place IL
their philosophy They worked upon
the theory that the dust abraded from
ihe crushed stone would OH the yoidS
between the angular fragments and
when wet serve as cement, thereby
making the road surface practically .
monolilh The iron shod horses aud
the iron tired wheels passing over the
road from time to time we're depended
upon 10 wear on sufficient amount OF
rock dust 10 replace that carried away
by wind aud water. aud this under The
action Of moisture recementod. thereb.
automatically renewing the bond Of the
road surface
The rubber tired wheels. moving ~
excessive speed fail 10 produce any
new dust from the rock, but the tire
meDdons shearing effect OF the driving
wheels loosens this dust and AS the
body Of the machine dispiaees a large
volume Of mir the detected currents
carry the rock dust OF the road. there
by erecting q permanent loss OF the all
essential binder II follows thai the
road IS soon stripped OF its dne bind
Ing material. exposing the upper OF
wearing course Of the stone These
stones robbed OF the binding material
nrc soon ioosened by the shear OF the
driving wheels. leaving the road badly
rayeled or disintcgrated II Is, Of
course. apparent that the effects de
scribed are greatly intensified on
curves. where skidding is most FIRE
qaent
Highway and mechanical engineers
have given much study 10 the action OF
the automobile on the road surface
aud many Ingenious theories have been
advanced While Il Is true that the
clipping of the tire. skidding. shape OF
the car body. suction of the pneumatic
tires. all contribute 10 produce the 81
feet, the most conclusive experiments
sepm 10 warrant the assertion that ih'
yrrat tractiva force OF shear eHerieo
by the driving wheels OF motorcars y
The main factor of injury.
A series o. tests eondurted by th'
Quilted States office OF pubic roads 10
ls.gs produced some interesting results
along ihis tine Cnrp Of various welciits
snd tyres were run over measured
course al different rates OF speed apo
right angie photographs taken OF en'h
nun A sixty horsepower car sirinped
yor racing. weighing with its driver
aud meShanician about 2soO pounds
WINS driven over this stretch u road ~
rates 8; speed varying from ure 70 STA
IL miles per hour. the sfss'd being IN
creased ave nliits per hour TOT each
trip over the roAd Up 10 uftccn miles
90 hsar little OF 30 eife,f was produced
% the road. but from twen,y mites 80
bouF the cfest was striking with esch
lnrrease 10 sfes-d These demuuStre
Hons proved that little Or no eGest b