The Providence news. (Providence [R.I.]) 1891-1906, 1895-04-05
AN AIR LOCK.
Beginning Of the River Tun-
mel for a Sewer.
a News Reporters Experience Fifty
Feet Under Ground.
Description OF the Method of Con-
ducting the Big Work.



Some persons take great delight in 'sit-
( ting /" on others, but to properly com
press a man so that he Will realize his
own iitlleness, just put him in an air
lock.
An air lock is not new to science, but 1t
1s something OF novelty in these parts,
and when THE NEWS man heard that
life sized air lock was in full
! blast on Hills wharf, off Aliens avenue,
1T the entrance TO the shaft for the big
sewer tunnel under the river, he went to
Investigate. Civil Engineer Otis r.
\ Clapp of the city engineers department
kindly acted as guide, and alighting from
the car at Henderson street, the new city
yard, with its fine brick barn, modern
stone crusher (but poor stone), and the
conyenience OF the new city wharf,
1t which stone, brick iron
and lumber can be easily landed from
aboard ships, were all pointed out. Then
turning to the left on Aliens avenue you
come to point opposite the entrance to
\ ths machine works where contractors
George r. Emerson 4 Co. are preparing TO
build a branch sewer, known as section
IS, to connect with the old sewer in
Aliens avenue, and with the tunnel.
This part OF the work necessitates the
temporary removal of several old houses
and buildings which have stood on the
Hill property for years, but they will be
6novcd back again.
Going diagonally across lots, following
thc line staked out by the surveyors, you
come to n long low, wooden shed like
structure about twelve feet from the edge
Of the dock. This building contains
+ the air lock and attendant machinery.
You have heard about tho air lock and SO
you ask to sec it and are surprised when
y what you took TO be dismantled hori-
Eontal boiler resting on tho ground is
pointed out to you in the foremost end OF
She building.
The air lock is an iron cylinder about
the size and shape of u 30-horse power
boiler and divided into three intercom-
municating compartments with a door
1T each end. The center compartment
rests on the collar of huge iron shaft
extending so feet into the earth the sink
ing OF which was only made possible by
the air lock.
Huge air COMPRISING engines force air
with . pressure OF from Is to 80 pounds
per square inch into the top of this shaft,
where the collar is bolted on. and conse-
quently into the central compartment,
which has a door at eac idc opening in
wardly. By this pressut u the air these
doors are made air tig1 Not finding
any vent at tie top this
( compressed air is forced down
I: into the shaft aud by its pressure serves
! to counteract the action of the water
which would otherwise back into the
shaft aud submerge the tunnelers, of
whom there are four in the day shaft and
6vo at night.
You express a wonderpent at the
thought of men entering that iron box
and then going so feet into the bowels
Of the earth 4" to work, and the
attendant engineer, william c. Holden,
says: "Woud you care to try it?
I've new oil skin suit you may christen
II you like; and you'll need it, for it's
pretty muddy down there"
SO of with your coats aud shoes and on
with n pair of rubber boots ami the oil
. skins, with a tsrpaulin tied under your
chin, aud three of you step into the first
I compartment just as you would step into
I thc fire box OF the big boiler.
Then comes surprise number one.
4 You find q workman there with
\ . lighte candle. lie stays there all the
sims to tend door. The quartet crouch
down, for the apartment is too small to
stand in, the iron door is closed behind
\ you and the workman says, "Are you
/ roadyf" just as IL you were going to be
shot through pneumatic tube The in
4 tcrrogation is the signal. however, to
. pinch your nose, for he Is about to let
some of that compressed air which is in
I the next apartment, come in through a
. valve, Ii being necessary to have an equal
pressure on both sides of that door which
y admits to the entrance TO the shaft be fore
& you can push the door open.
"Let 1t come easy, )" says MIR. Clapp, with
Sis nostrils already closed.
\ And IL comes "easy." 1t rushes in like
h whirlwind from somewhere or other.
with roar and Kissing like
:. csnnonsding and escaping steam
!. combined. The candle flame is e1-
: tingusbed. Ii is almost sitting hot.
!, the air becomes oppressive aud YOU
q breathe hard and fast, through your
( mouth, and IL tastes OF tar; and then your
! ears begin to ache. especially II the men,
= brsnss are at all weak, in which case a
I, rupture il liable to ensue and the blood
: chat might have flowed from the nose il
0 yeu had not "pinched" it, trickles out
and down your neck.
q But suppose there Is no rupture and you
: can sigrin and bear it," especially when
= told that II is almost over, you cannot
], help wondering what the sensation would
!. be like II IL came other than "easy," and
Z while trying to frame an answer the door
D opens and you look into the mouth OF
the shaft. IL is an ominous looking
I. hole In the ground filed with vapor,
/, caused by the warm compressed air COM
|. ing In contact with the dampness, which
< Il vaguely illumined by an electric light
Stationed somew here in the depths below
The workman relights his candle and