The Port Gibson herald, and correspondent., 1850-03-15

will be necessary to relay the road, as the knots
will then so project above the surface as to |
make the road too rough for comfort so that |
S22,7l4 80 may be expected as the net pro- |
ceeds of eight miles of plank from tolls.
"From our present knowledgeof the subject, |
we should say that, before hemlock plank is |
worn out, it will earn FROM $4,000 to 5000 a |
mile, over and above repairs and costs of co.'s
lecting tolls. Experience in many different |
roads will only determine The precise amount.
'Sand, or dust, or tan bafk, put upon the
plank, would do much 10 prevent wear, and
where such substance can be had at reasona-
BILE cost they should be used Where the road
is TO run over sandy country the facilities for
using sand for covering will tom an important
fact in determining the durabilityot the road.
mo plank road made Of hemlock has been in
use long enough to decide now long the plank
can be preserved from rot. Seven years is per-
haps as long as it would be prudent to calculate
OH their lasting. Some varieties d hemock
are much superior in all respects to other varie-
ties but it is not likely that the average duration
of the planks will exceed seven years. Pine in
Canada has lasted about eight years.
in determining upon the probabilities OF any
proposed road paying well, 1t will be best to count
the teams for a short period of'time during such
part of the year as gives about an average OF
the travel, and then by calculating the tolls that
these teams viii pay, and suchincrease oftravel
as may reasonably be expected TO grow out Of
the construction of the road, it will be easy to
determine with sufficient accuracy whether
there will be travel enough 10 owear out the road
within the time that it may be supposed it can be
preserved from rot.
'Thus far, hemlack only has been used for
planking roads III this country Some locations
furnish other kinds OF timber that probably might
be used with great advantage. Hemlock is very
knotty and the knots are very hard, thus soon
making rough road Oak, maple or beach
would any o! them be better. In some of the
Western States white oak is so common that ID
MANY cases it would be the cheapest timber that
could be used, and its lasting qualities are such
that road made Of it would be profitable, where
the reverse would BE the case with hemlock.
"rhe Syracuse and Central Square plank
road was the experimental road. and was con-
structed without any previous experience or
practical knowledge of the subject, and, as might
have been expected, some mistakes were made,
and much has been learned during the two
years it has been in use, as its detects have be-
come apparent.
much as hemlock plank can be worn before the
knots will make the road too Tough to travel OH.
One inch is sufficient to hold tie knots from
splitting cut, so that three inches is thick enough
Tor hemlock plank, and i; they are any thicker
it is a: useless expense. Strngers four inches
square were used on the Syracuse road. Ex-
perience has shown that more strength should
be given to the stringers and that they should
be laid five feet apart from outside to outside, so
that the wheels may pass as near as may be d.
rectlv over them. Ii the plank are but three
inches thick the stringers shonG be foot wide
and three inches thick, To give strength to the
road in the direction OF length. The strineers
/ being twelve inches wide, there will but three
| feet of space between them and the weight OF
! the horses as well As the wagons which pass over
them. Il the stringers are laid near The ends
Of the plank the plank will spring inthe middle,
and by the ends being held up they will become
bent down, thus making a depression in the mid
die Of the track. II the striugers meet at the
ends without any lap or anything to splice the
Joint, they settle and become gradually bent down
at the place Of their meeting. To avoid this,
Fthe stringers should be made of two pieces, each
piece six inches wide and three inches thick,
and laid side by side, so that where the ends o.
one set of sticks meet each other they will be In
the middle @! the stick by the side of them. thus
breaking Joints This could not be done with
out having the stringers sawed in two pieces.
"In Canada it has been found that the string
ers, being excluded from the air, do not decay a:
fast as the plank, and that two coverings o
plank can be used upon one set OF strlngeTs
Thus it is economy to strengthen the road BY
strong stringers rather than BY thick plank.
1.-The great difficulty with plank roads is t.
keep the water from floating the plank. The
rain falling upon the top OF the road, unless The
water Il allowed TO run out freely, will pas:
through the cracks between the planks, ant
then, as the earth is banked up to the top OF The
plank at both ends, the watercannot escape, un
less the soil is so loose as to allow. it to settle
down through it. The effect of the passing 0
The loads over the road is to press the tlmbe
upon the earth, and very soon it becomes packet
very hard, and if any water is allowed to &c
under the plank, great injury arises from It, 10
it is but rare that it will drain away before tn
teams that pass over the road will cause Ito H.
up between the plank and bring with it fine par
ticles of earth anC deposit them on the top Q
the road, and thus excagate cavity under tn
plank; then the loads will spring the plank dow
unless the stringers are strong enough and iiea
enough together to hold everything up When
ever the planks are allowed TO become loose an
move under the loads they go TO pieces wit
great rapdity. T4is is shown most fully upo
the Syracuse PIX pad. In snch places as tn
water has setcied under the plank and fioate
them, they are nearly destroyed, while in thos
parts of the road that the water has been keE
rom under the plank, they are comParativel
but little worn.
sin single track road the plank should b
eight feet long, and should be laid on one side
the centre of the road, and they should be o
that side Of the road that is used most by th
loaded teams The ends Of the plank that ar
in the centre of the road should be three inche
higher than the ends of the plank next tn
dilch, so that the water may run freely off froi
: tine centre of the road toward the ditch. Th
earth should come up to the top Of the plank q
: the ends, so that teams may pass on and 0
freely, and the ends of the plank should be a
lowed 10 project, once in two or thi ee feet
the general line, two or three inches, that til
wheels NAV the more easily rise on the top
the plank IN case a tut should be made at th
. ends. The earth.siiouid fall off at the rate
two inches to the foot from the ends of the plan
; toward the ditch, which should be at least on
foot lower than the top OF the plank. On Ii
: 6ther side of the centre of the road there mu
Be a good earth track, ten or twelve feet
ft,;Jtt, ant unon This frnnk ehou