The Columbian. [volume] (Bloomsburg, Pa.) 1866-1910, 1893-12-08

ets snail be at least three and one
halt feet in length and not less than
(ao) inches bed for a sixteen (r6) inch
course, and not less than twenty.four
(24( inches bed for an eighteen GS)
inch course. and not less than thirty.
two (3a) inches bed for twenty-eipht
I aS) inch course when the thickness
OF the wall will admit of it, the head.
ers Will lnterlock but when the wall is
too thick to admit of this Arrangement
they Will be bonded with large back
ing stone, laid over them to connect
two opposite headers. The stone for
the heart of the wall will be the same
thickness as the face and back, well
behded but not jointed, but must be
well htted to their places any re.
naming interstices must be filled with
small sound stones and backing to be
set In good bed of cement mortar
and mauled to place, the interstices
may be laid dry and then every course
grouted separately.
lhe face stones Except the ice
oreakers) shall be left as they come
from the quarries unless the project.
ions above the draft should exceed
tour inches, when they are to be scab-
oied down to that point. Upon the
points OF the piers which act as ice
breakers the projections shall not ex.
ceed two inches. The abutments and
piers shall be covered with course
OF coping sixteen (r6) inches thick,
each stone to reach the entire distance
across the pier or abutment and pro-
ject three inches over the wall on
each side and to be not less
than three feet wide. Especial care
is to be exercised in preparing
the beds for the coping upon
which the foot shoes of the bridge
rest. Drafts one and one-half (I5)
inches wide are to be cut on all the
exposed courses of the piers and abut-
ments.
The wing walls of the abutments
shall be of the same quality of stone
and shall be of the character of work
known in railroad parlance as third
class masonry. The wing wall to be
covered with a coping not less than
twelve (I2) inches in thickness and to
project two (2) inches over the wall.
The masonry to be laid with good
cement mortar composed of one part
in bulk Of well burned and seasoned
Rosendale (or other equally good
quality to be approved by the En-
gineer) cement to two parts Of sharp
clean sand free from loan or clay 1t
should set in from thirty (3o) minutes
to one hour, then be immersed in wa.
ter, show tensile strength per square
inch of section in "a hours of at least
twenty (ao) pounds and in one week
Of forty (4o) pounds. No mortar
should be Used after it has been mix
ed and left stand over one.half hour
alter water is added.
The Grout shall be made in like
manner to mortar as to proportion oI
cement and sand and only differ in the
quantity of water used.
The prices agreed upon and pait
per yard for each kind of work shall
include all expenses attending the de
livery of materials and incident to the
prosecution of the work and cover al
risk and damages by flood or casual
ties of any kind.
No claim for extra work shall be al
lowed, unless the same shall have beer
done in pursuance of written orde
from the Engineer, and the same mus
be presented at the first settlemen
after the work is done, unless the En-
gineer in his discretion should approve
the claim Or any part oft which he ma.
deem equitable.
SUPERSTRUCTURE.
The superstructure shall be all opel
iron and steel truss bridge ofsix spans
{ each in length one hundred eighty
nine (rS9) feet from center to cente
. of pins, or total length of elevel
hundred and fifty (II5o). The road
/ way shall be eighteen (IS) feet in tn
clear, steel joists with two and one-hal
(aJ) inch white oak flooring. The bridg
shall have capacity of fourteen hun
dred and forty 44o)poundsp per linea
foot for trusses, and one hundre
( (Ioo) pounds per square foot for fool
with safety factor Of 81" With tn
E exception of the flooring, the entlr
superstructure to be of iron and steel
The style and design are left to tn
e contractor. but detailed drawings ar
e to be submitted to the Commissioner
e and approved by their Engineer bctor
the work begins.
r GENERAL CONDITIONS.
d Contractors will be required to Civ
j. their personal attention 10 the wor
J. and will not be allowed to sub-coI
/. tract the whole or any part OF tn
(, work without the consent OF the Con