The New York herald. [volume] (New York [N.Y.]) 1840-1920, 1871-08-08

A Reply TO Orc Of Yes 'crdny's Letters

A Reply TO Ono Of Yes crdny's Letters.
To THE EDITOR OF THE HERALD:- r.
Professor Van der weyde, who is well known In
this community as careful experimental, skilful
chemist and able writer on technical and scientific
subjects, has, regret TO notice, taken up o sub.
ject to which lie has evdeltly net given sufficient
thought, as III his communication published IN your
valuable journal this morning he has made many
statements which are either palraoe errors or else
OF the character which little thought and cal
culaton can disprove. Had the communication
emanared from any less prominent source 1t might
have been overlooked We throw nine tcnhs OF all
the ink.snging on The subject OF boiler explosions
into TIC waste basket but Professor Van der Wcydes
arguments Mast be met and disposed or else seroua
wrong may be done. He says ~ set down as q
MAXIM that the cause 0i all boiler explosions Is that
the cohesive force OF the weakest pert OF the boiler
has become smaller than the strain produced on IL
by the pressure of the seam" II he had LETT Oh me
last six words quoted his maxim would have been
more reliable ana could have done no harm.
1t Is fact which all men who presume
to discuss this intricate slhject ought TO
know that any tube closed at the ends
W be Tupt,red onatudnay with hair the pres
necessary TO rupture 1t transversey. Then, as
the boiler OF the Wesreld ruptured transversely Is
not probable that the explosion was caused by the
pressure OF the steanl Further, any piece Of iron
subjected TO tensile strain Will be permanently ex-
CURED to break 1t. Therefore, OF some other part
oi the boiler OF equal strength with the part which
gave ~ay Is not found permanently stretched ex-
Tended Of tulged out it is evidence that II was
not the elastic u,~nssure OF the steam that caused
the rupture Again. .v s a T1 o ~ sTe
dinaly and most enectireY ass sno pressure Oh
the steam actng TO cause one ire aSSintv
large los, which would more tha,. ~. ~ ~
to resist that kind OF force. The nSc. al .ne
longitudinal stays he recommends Is not 8. ivan
ent az he claims. with pressure OF twenty-sS :"
do ofq at m N
against the back head or the boiler having the tel>
dency TO pull 1t In two would be j,343 mounds,
which seems to he q tremendous force certainly;
but then there was, without estimating the iron In
the tubes, ninety. -four square inches OF iron to be
tensile strength at 200 pounds to the inch,
1t could restrain 1Sso,ooo pounds-or 1t has
Than s mes the the strength on
the boiler IN his communication Is not pertinent to
the question, as The line OF fracture nowhere inter.
sected a patched weakness Therefore II Is fair to
conclude that II the boiler had been all made Of
patches 1t would not have burst The want OF ex-
actness of statement which pervades the communl-
cation Is much 10 be deplored and Is not character.
stic OF the writer In referring to the weakness re-
ABOUT half the metal being removed" whereas.
I'm fact, less than One-thrd or the metal was re-
moved ana instead Of the iron beng 81 pre
sented up to this time by the experts VINO
have been examined, and; In fact, the appearance nee
peror quaty. He ciiticises injullciousy the cnar-
acter Of the test by hydrosiatc pres sure" assert;
IL
OF thirty.four rs Intended" although mere was
probably reliable evidence or the iact statcu. III
fact. the Inspector did not SO state ~ wnle uIaer
oath. Yet, even II 1t DO the iaSS tn ms
It was so, It would only show ,,d tnat 'a no
limit of pressure Of the steam aliow1a 10
the engineer might have been even hiyner man .
twenty-five pounds tlc also say, mV Sanu ume
legal limit OF hydrostatic pressure may star, uauWsr
Gus cracks In an old boiler: 10 uI,S ,a -
he retorted, 'what Of 1t II 1t may; provlu ,s 10
when hot than when cold" which Is exactly the 0p:
nose of the opinions OF engineers generally aud all
tnspectors of boilers, within the limit OF the temper
ainrc of water In boilers; and committee OF the
Franklin institute, by elaborate series oil expert
| memls determined many years ago that iron m.
creased in strength was heated up to about 900
degrees Fahrenheit ''The indifference OF proprie-
tors J; inducing them to retain In use old boilers
most t'p engineers that an old boiler which
| will stand q given hydrostatc pressure -
| better than new one Of the same ability as the
new one Is full OF initial tensions and strains while
the old one IL well annealed giving improved ductl-
| ity or toughness 10 the iron, with which 10 would
| stretch easier. and thus show on It's outside the
| erect OF oyer-pressure--a very desirable quality
possessed by copper, which, but for It's cost would
cause 1t to be used the material for boilers. 1t ID
| well known that annealed wire Is much tougher
tnan cold drawn wire. with reference TO tho
| advice to adopt thermometers for the determ,na.
| ton of the pressure, 1t must be said constant use
| dlsarranges them; they are quite liable to break
1--WE on six having broken on one boiler in one day
within this writer's knowledge-and when the steam