Evening star. [volume] (Washington, D.C.) 1854-1972, 1861-01-03

SMITHSONIAN Institute Second Lecture of a
e0wss on Roads and Bridges, by Prof. Fairman
Rogers, of the University Of Pennsylvania
The lecturer having treated Of the location Of
roads in the previous lecture now took up the sub
ject Of their construction. In any road a regular
cross section and a smooth surface are important
The width will depend upon the trafic expected;
In new countries sixteen to eighteen feet will be
sufficient, that width allowing two vehicles 70
pass easily and not being too great to be kept i'm
good repair Near large cities Il must be increased
to thirty forty, or even fifty feet A width too
great for the trafic involves unnecessary expense
The surface must be such as will remain smooth
and not be much affected by the weather
We may insure such a surface by thorough
drainage and proper covering. The drainage il
Of the first importance as water is a great enemy
to road by washin: it into gullies, forming mud
and breaking up the surface by freezing In cold
the cross section and partly upon the material.
As to the general cross section, the road bed
should be, II possible, higher than the surround
ing land, IL should have a sufficiently deep ditch
on each side and the surface should be slightly
sloped to permit the water to drain off
We frequently see roads which are nothing
more than bitches themselves, from being dug
down below the level Of the land so that water
drains into them, instead of from them. When
the road must be lower than the land, Ii should
be well drained by bitches The road itself
should not be crowned or made with a curved
cross section, but rather with two slopes joining
in the center Of the road. III the surface is kept
In good repair one quarter Of an inch to the foot
should
always be made at least on one side. Everything
else being equal, road is better the south side
If a hill than on the north; il is dried and the
snow and ice leave II sooner. Although shade
trees are considered by some engineers as tending
TO keep road too damp, they add SO much 70
the beauty Of route and to the comfort OF trav-
elers that they should always be planted IL prac-
ticable. With some soils a very good road NAV
be made by attention TO the foregoing principles
but to make frst-class road some covering is
usually necessary. This covering should be
smooth and hard, but not slippery Gravel, cinder
and slate will generally make such a surface, but
hard tough stone broken into small angular pieces
makes the best covering. We call roads made In
this way turnpiked, or macadamized roads
The Lecturer then discussed the relative advan-
tages OF broken stone on paved foundation tel
fOfd's methOd) and on a Yielding foundation,
(McAdam's method) giving the preference rather
To the former, when 1t is possible to incur the
greater expense.
On all roads a system Of constant supervision
and maintenance Of the surface is greatly prefer
able to the usual spasnlodic repairing. Plank
roads are useful in certain situations although
experience has not shown them to be as perfect as
was at frst supposed
A good covering for city streets is very di ficult
to obtaini macadamizing being Objectionable on
account Of the dust and mud, paving has been re-
sorted TO. Cobble and broken stone pavements
as usually made, are rough and noisy. Cut stone
pavements, such as that known as the Russ pave
meni, are the worst that have been tried-very
expensive and very dangerous, owing to their
smoothness. Small stones very carefully laid in
concrete would be probably the best. Iron, owing
to various reasons, has only been used with mod
crate success. Asphalte, If less expensive, would
be most admirable material, and has been used
In Paris with great success Our varying tenn
Perature renders its use here less practicable.
We were In error In our report Of the last lee
ture in attributing the lines on the AZ pine roads
TO the pen Of the lecturer. They were fCom the
poem of Italy," by Rogers the English poet
The reason for the mistake is obvious.
CENTRE MARKEr.-The market place, this
mornings was wet, muddy and entirely uncom-
Portable. The attendance was slim, and business
dull, Of course. The prices were about as fol.