The Seattle post-intelligencer. [volume] (Seattle, Wash. Terr. [Wash.]) 1888-1914, 1894-07-26
THE SEWERS.
The Percussion Theory Thought to BE
Intensble.

The Percussion Theory Thought to BE
Untensble.
SEATTLE. July "a. 1894.
To THE EpIroR: In today's PosI-INTEI-
LIeEscER the city engineer gives 1t as his
professional and official opinion that the
breskage of the sewers all over the city is
due to percussion. Since the first dis
covery of the breakage the engineer has
persistently refused TO take natural and
reasonable influences into consideration
as the causes of the damage. but rather
persists IN seeking for visionary and un-
natural causes to help him out Of the
dilemma.
At first theory OF dynamite explosion
was advanced The public mind was then
agitated over the great strike. 1t was be-
lieved that under those conditions the
public would believe in any hoax. Thus
1t was thrown out as ''feeler" that per-
haps some public enemy. presumably and
preferably the union bricklayers, had
hoated dynamite into the sewers, and
hence the breakage.
But the people of Seattle are accustomed
to do their own thinking. They were not
aware of having so pernicious q public
enemy in their midst. Least of all would
they for one. moment suspect the trades
unions OF this city to be public enemies.
The absurdness of that theory was SO
manifest that il was quickly abandoned,
and new one, though less malicious, but
equally as ridiculous, is advanced
Percussion Mr.. Thomson concludes to
be the cause. Tile Is somewhat timorous
about the advancement of the percussion
theory. lie tells US that "some persons
have been inclined to ridicule this percus-
sion theory, as they cannot see how a
shovelful of earth thrown on pipe can
break pipe which will stand strain of
from {, 900 to 10000 pounds" To guard
himself against that ridicule he cites tor
sign authority. Sir Joseph BazaIgette,
who dropped an iron bail weighing four.
teen pounds on an ironstone pipe aud
succeeded in breaking the pipe
Now, what consolation does Mr.. Thorn
sou expecSto derive from Sir Joseph Bazal-
gette's experimental The ironstone pipe
being the softer Of the two substances. II
naturally yielded to percussion of the iron
ball aud broke. If the filing in of the
sewers of this city were done with broken
stone. gravel or Jumps OF hardpan, thsn,
IL thrown In carelessiy there might be
something in the percussion theory. As
shoyelfui after shovelful OF dry. hard
Jumps is thrown on the center of the pipe.
the dry Jumps viii jar the pipe and roll OFF
to both sides. Continuous jarring is apt to
cause break, but as soon as the earth has
reached level with the top of the pipe SO
soon Is all danger Of percussion passed.
But with wst, soft clay, there never Is
and never can be any possible damage
done by percussion, for the very simple
reason that the very first shovelful OF wet
clay thrown on the TOP of a pipe sticks to
the pipe anG forms natural protection
against any damage from percussion.
After the first half dozen shoyelfuls
have been thrown in there is absolutely no
jar on the pipe. AS to the possibility of
the first few shoyelfuis having done the
damage, that IS nonssnsical. The clay be-
ing soft il is piiable aud yields to the hard
ness of the stone p pc.
The city engineer attempts to aid his
percussion theory by tack hammer illus
tgation. lie SAYS: eff you rest a tack
hammer on the head of tack il is nrsss-
ing on the tack i'm the same way that the
direct pressure 10 brought to bear on the
pirss in testing them, and will never
driven 1t into the wood. but If a child lifts
the hammer and strikes the tack with il
be will soon drive IL m"
10 is hard 70 conceive how the tack
hammer illustration has any bearing on
the point al issue. As matter OF fact Won
can force tack into any substance bv
either driving or pressing. providing the
Substances Is softer than the tack.
Leaving visionary and unreasonable
causes out OF consideration, there are eut
two causes To which the brsakAke Of III.
seweE pipes can be attributed. Oae i
poor pips, the other the poor laying of the
pipe The Graf cause Is out Of the of.es-
bon, since IL has been repeatedly demon.
strAted that the Denny Clay Coansnv
pipe Is equal. IL not superior, 10 anv Other
made in the United States. The see
cad cause, the poor laying Of tbs
pipe. Is the sole reasonable caass
10 oe tsksn into consideration. ard
Tor that cause, the only person that can
! justly Re held responsible Is tue city enes.
neer Moreover. the very fact that he /.
- Ar1sEuy engaged in En9iug visiopsrv
es1sss. and that he - extremely miniElaiz.
ing the damage done. proves thas he
Eaovs that be Is guilty and nov iriss 20
sAlfs ths blame.
We're this pager written for technical
pssfa o. investigation, evidence cauEd
sAsaly - pzoagss1 20 pEoxs psrona .