Evening star. [volume] (Washington, D.C.) 1854-1972, 1892-02-19
a ROCK BorroM.
Result Of the Test Bersnss on the Pess o.
site.

sArr FOUNDATION Tor TIE prrrxa In
LIEvrp TO HAVE BrES POUND AT A prPrH on
rHfRrr-FIyr fEEr BELOW rHK rxcAy,rrox-
RESULT OF THE BoRSes
There is rock under the post Office site
beyond doubt This valuable Information
WAS ELECTED yesterday afternoon BY the 'borer
who is nov engaged in sinking two-inch
shafts In the square. in the direction Of
China, and confirmed this morning, ana
those who are engaged in the preliminary
work Of the construction Of the building are
quite happy in consequence.
The rock that has been encountered 10 about
thirty-hve feet from the bottom Of Contractor
Gleason excavation. and there is now reason 10
believe that IL Is continuous over most OF the
square. This as ten feet nearer the surface
than was at first estimated by Mr.. Edbrooke,
the supervising architect who started out in
his planning with the belief that he should get
a rock bottom Tor his piling at about forty
five feet. Ii Is at least a hundred feet closer 20
the level OF the street than was predicted by
those who have been crying against the site ~
a mud hole and presaging dreadful thincs for
the building II built there.
The frst sign of rock developed by Mr..
Conley, the borer. at about 2 O'Clock Yesterday
afternoon. He had been grinding through .
bed Of gravel that offered great resistance 10
QTlu LOT some time. ana al lArt ne tounQ
that there was ring 20 his rod as he pounded
il down and the water that he sent through the
drill tube did not come back to the surface
through the casing. This was an almost infal-
lible sign that there Was water VEN IN the
vicinity OF the steel drill such il ordinarily
Encountered below a bed OF gravel In fact the
conditions were very favorable for the devek
opment Of n rocky bed for these submarine
streams, as il was evident that the water that
was being sent down the tube found an easier
q Of tha nj cfr m lusIn0
than the vertical current TO the surface
ROCK INDICATIONS POSITIVE.
The particles Of gravel, too, began TO grow
less and less, and at last the bucket that caught
the outflow contained fine silt or sand such
as is commonly encountered on the top Of rock
over which underground streams fow. In .
Few minutes the indications of rock became
positive, and Mr.. Conley kept his drill going
for some minutes, eating his way down into the
rock and bringing back shining sand contain
ing particles OF mica and flint At the depth Of
30 !eet inches from the surface. or "a feet
Va inches from the grade line-bottom of the
excavation. from which all the official calculs-
lions VIII be made-the drilling in pit No.
was stopped, and the tools were removed to
the opposite corner-on ID street-where the
Ice companys office stood.
In view Of the general belief that there
would be no rock within fifty feet OF the sur
| face II was feared that the drill had merely en-
countered a chance bowlder too large 10 be
! forced to one side. and that the next pat would
develop d different state Of things. The
suits OF the second borings. therefore, were
watched with the greatest anxiety by Superin-
! tendent Steward aud his assistants. who realize
the value of bed Of rock.a such u small dis-
lance from the grade.
The work in pit No. 2 Was begun at about 6
O'Clock yesterday afternoon. but the drilling
was Kept up at intervals until this morning at
IL, when rock was again found at practically
the same depth as IA the other nit
This result almost wholly dispels the fear
that the first rock Was but bowlder and 10 20
far corroborative that II may be assumed for
the present at least that there is q stratum Of
rock under the site throughout the northern
end OF the square.
RESULTS OF THE BORING.
The intermediate strata OF the two pits do
not exactly correspond. though there IL nearly
the same order. The following tables show the
results Of the borngs in the two places, the
figures being the distance IN feet and inches
from the surface Of the ground on which the
derrick rests Ia each this - the bottom
OF a cellar. AID thus Is below the apparent sur
face Of the square, though not quite dosa -
the grade level OF the excavation:
FIT NJ. 1.
Surface-Soft mud.
5 feet-Red clay.
Is feet pa inches-Clay, trace OF sand
10 feet az inches-Blue clay.
"a feet inches-Blue clay and sand
"a feet IA inchcs-Sand and gravel.
IS feet "A inches-Clay and gravel
30 feet q inches-Small bowlders
81 feet 3 inches-Sand. tine gravel
SO feet Ia inches-kock.
Pit No. e
Surface-Red clay.
foot IL inches-Blue clay.
2 feet Inches-Red CLAY.
Is feet inches-Sand and clay.
n feet 4 inches-Blue clay.
~ feet lnches-Blue clay and sand.
20 feet z inches-Blue clay and fine gravel
~ feet "a inehes-Hard pan Cfne ssnd).
80 feet 81 inches-Gravel
80 feet lnches-Clay and gravel
IS feet g. iuches-ltock.
Ii will thus be that there Is q bed q
gravel several feet deep on top Of the rock In
each place, and this has been found by the drill
ing to be very hard and difhcult of penetration.
In such cases a gooa hard gravel is all that 10
sought by architects, ar II will hold piIing suf-
| hclenty well to insure the complete safety Of
any-building. Indeed, Mr. Conley. who has had
| along experience with such work. is OF the opin-
ion that there is now developed sufficient base
| tor a foundation for the pest Office without any
piiing Mt all The architect, however, will not
be apt to accept this view OF the situation, Tor
| he Id ANXIOUS to obtain q foundation for this
building about which there viii not be the least
question or doubt.
| ADDITIONAL BoRISoe TO BE MADE.
Much will now depend upon the results Of
the boring to be made in the southwest corner
of the square, as it will then be seen whether
the stratum of rock extends southwark OF 10
confined to the north end Of the lot The
fourth hole will be sunk in the sou theast corner
and then there will be others sunk at various
| places to be determined by the architect -
| soon he has examined the results Of thsss
| four borings carefully.
The depth Of the rock encountered 10 a
course a grave matter. and this will doubtless
be investigated before the borer rs released
| from his contract In the hole number one hs
went down about two inches into the rock with
out developing any change in the conditions,
and il is likely that he wentas far into the stone
| at hole number two. should he find rock st
each of the four corners he will probably be
| asked by the architect TO drill down several
| feet into the material. this stratum may be Q
| mere shell of stone under the gravel and there
| Ia. ,,oclnts hal.,u NJ and ar <x....I -