Evening star., 1934-09-02

hoVCc hUOuC Tie DcSt way 70 reueVe the excessive
strain near the outside surface of the lower
structure. 9
As most people already know, marble Is laid
very much as bricks are laid. That is Joint to
joint with layer Of mortar to hold the various
blocks together. This is the way the marble
sections Of the Monument are connected. So 1t
was comparatively simple for Dr. Kessler to
simulate the substantial construction. Of our
great memorial IN his laboratory.
AS his test materials the scientist selected
IS marble cubes. inches square, each weighing
about SO pounds, made Of the same kind Of
stone as the Monument and weathered to al
most exactly the same degree.
Next DR.. Kessler cemented two of these
blocks together with thin layer of mortar, in
substantially the same way as the actual
Monument blocks are welded He then placed
the experimental cubes In the gi&ht testing
machine in his laboratory. This IS probably
the largest in the world, with a 10 900 000-pou
capacity. The idea was to subject these marble
units to even more powerful pressure condi-
tions than those actually found in the Mpnu-
ment itself. In fact, each experimental stone
was subjected to strain enough to make it
reach the breaking point
Since this was primarily a weight redistri-
button test, the scientist previously had cut back
the joints on the blocks about one and one
fourth inches and refilled these cut-b back joints
with more elastic mortar than that used
The test was success. Under similar pres
sure conditions as those found in the Monu-
ment the test blocks stood far more than the
necessary strain without shipping, or "spalling,"
as the scientific term has 1t. In his next
experiment DR.. Kessler cut back the joints Of
the experimental blocks to q greater depth
one and three-eighths inches to find the mini
mum depth the joints could be cut back and
stu not chip under the tremendous pressure
exerted upon them This test also was sue
cessfuI. teg4
Within the very near future, the Federal
experts, 1t is understood, will apply the new
method Of weight redistribution to the Monu.
ment itself. What they probably win proceed
70 DO, DR.. Kessler explains, Is to redistribute
the entire lower section of the Monument-from
the 150-foot mark to the ground level. And
tney won't need to remove q single block Of
marble! Which is very fortunate, indeed For
each marble block In the lower section weighs
about three-fourths Of ton, is some 2 feet
high, 6 feet long and about inches wide
[ IERE'S how the weight of the entire lower
Monument can, and probably win, be dis
tr1buted. IN DR.. Kesslers opinion: The first
requirement Is to have made modification Of
one OF the present-day stone-cutting saws
well known in the building industry. This type
OF saw Is really an abrasive wheel and should
be slightly thicker than the Monuments pres
ent mortar joints, SO that it can be used to cut
back into the horizontal mortar joints q pre-
determined depth, probably not more than
one and one-half inches.
The actual marble thus cut away would not
be more than sixteenth of an inch on each
adjacent block, Dr. Kessler says, capable of
Deing handled by only two men, could run
through from one side of the Monument to the
other, within q half hour period. This mech.
anism would work by electricity. Sturdy scaf-
folding placed on the outside Of the memorial,
would be used In connection with the giant saw,
so that after one complete section Of marble had
oeen cut through, the workers would simply
move the saw and scaffolding to the next point
OF attack. Saving operations could be started
either from the bottom of the memorial gradu-
ally working up to the 150-foot level or from
the 150-foot mark, working down.
After all the mortar joints in the lower
Monument have been cut through In this
fashion, DR.. Kessler says the next step would
be to put q more elastic type Of mortar into
the area thus cut away. However, 1t would not
be necessary to start Immediately filing In the
newly-cut joints with mortar. For, after all,
It takes three to four days for mortar of this
type to harden.
Just how win the Federal experts solve the
problem Of Strengthening the numerous hollow
places In the granite rubble. which section being
about II feet thick at the Monuments base,
takes up the major portion Of the 150-foot lower
section? This should be comparatively easy.
DIR. Kessler believes Workmen. under the
supervision Of Government engineers, would
simply MI in all the hollow places with high
grade mortar. This would strengthen this Sec
ton and tend to equalze the distribution Of load
after subsequent settlement Of the structure.
How would this Strengthening mortar be
placed into the granite rubble? First the
workmen would bore numerous holes, say about
10 feet apart. clear through the granite. Into
these holes pipes would be sealed. A hose would
pressed air, new mortar would be forced In,
DIR. KesSleY explains