New-York tribune., 1901-03-24

with the main subway system will be at Han
over and Washington sts. The distance from
Maverick Square TO the har5or is about 200
feet; the width of the harbor at the point OF
contact is Loo feet more while the distance
from the peninsula shore to the end of the pro-
posed tunnel is nearly 3.2No feet.
The line is divided by the engineers into three
sections Section extends from Maverick
Square $40 feet, and this is completed The
work, which was finished November 50.
done 10y the National Construction Company. of
New-York- Section II. with a length of 4.4;;O
feet. is in the hands of the Boston Tunnel Con-
struetion Company. This has carried the bore
little than hundred feet further
toward the barber. No work has vet been at
tempted on the peninsula The work on Sec
ton G, and the last. $40 feet is vet To be let
IL expectation he met. Section Il Will be finished
two years from next midsummer. Probably
three years hence trolley will be running
under Boston Harbor the entire length of the
tunnel The work Of boring proceeds at the
rate Of about five feet day. OF course. the
operations go night and day. as there
two relays of about hundred and ten men
each The cutting is through b,uc clay. rock
having been met with In fact. no more stub
born substance is likely To- he met anv of the
way, unless near the peninsula end Of the tun-
mel
The great mechanical feature of the boring is
mammoth steel shield. Weighing sixty tons.
The power used to push this forward is con-
tanned IN eighteen jacks each with a forward
thrust equivalent To sev .nty- two tons AT pres
ent the forcing agency is steam. but compressed
air will soon be substituted. The shield de-
scends about five feet in each one hundred feet
OF progress Another interesting feature is the
manner in which the eXcavated material is re-
moved NJ the upper level of the elevator is a
broad platform on which are stationed several
Siii'ili ears that run on surprisingly narrow
track. Into these hliputian ears the mass
brought up is dumped; then they are run over
trestle to a terminal where there is another
platform with openings through which the con-
tents of the vehicles are dropped into cars
belonging to the Boston and Maine Pai,road
The company is willing 10 carry off the dump
ings for uses of its own
The chief building material OF the walls OF
the tunnel is concrete. and the huge. cubiforrn
box called the mixer whirIine with great
rapIdity. is one of the most striking sights in
the cut, fifty feet from the surface. The facin;
or the walls is of granite, and the coping is of
the same material The following general de-
scriptlon of the structure is taken from the
current report of the Boston Rapid Transit
Commission:
The tunnel will he an arched structure for
TWO electric railway tracks. The portion under
the harbOr will be about 2lIe feet high inside
anu about - feet wide. and has walls of ;si
inches and upward in thickness The tunnel on
the East Boston side has grades of from 4 to
- per cent, and at point 2,yO feet sOuthwesterly
,toin ,r.n the Harbor Commissioners line is about
ioV feet lower than in Maverick Square. n
length OF about $50 feet in mid harbOr il
nearly level Grades of 3 per cent occur on the
Boston SIDE but are OF short lengths, owing to