New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1875-04-26

STRENGTH OF WOOD IRON, AND STEEL.
rrsrI1s OF EXPERIMENTS on THE SET or BARS OF
WOOD IRON AND STEEL RESULlING FROM
TR,NSyERsE SIHHss-BY PROF. ". A. NORTON
or YALE COLLEGE.
Il will be remembered that Prof. Norton
submitted AT the meeting OF tho Academy IN April last
the results Of extended series OF experiments on the
residual detection OF rectangular bars OF white pine aier
having been subjected to transverse stress lie h'u
since made great number OF similar experiments ON
bars Of wrought iron steel the results Of which were
discussed m the present paper. Our space viii permit
The giving only the conclusions arrived at after very
extended series Of Xperments which were that every
on,,irlfinu of "A transverse stress to bar mus.
induce change in its molecular condoh' wien wien
continues with variations that may be ethcr
progressive uctuating, for q greater or tess
interval Of time. The duration OF sshSlpe in"eHcr
varies with the amount aud duration OF inc sre7 roi
the smaller strains II j. but few minutes; tOf the arg
from day to day to bar Wa parent IRON te lc VIZ.
the same stress did not different days produce either
the same detection the same set u was stIlKhgy
SHOW n N The apartments with the steel bar. by causing
tie bar which loads had been repeatedly applied i0L
conparn detection ana set with those obtained I'M
mecy before the reversal 1t was I0und that inc ue
The detection produced by the same weight Just before
The reversal aud the set obtained was now many times
greater than before The detection also now increased
with proOn cation Of the strains. whereas II before de
creased The set also increased after the load was
removed, whereas ii before decreased.
There doccrble lim OF elasticity revealed Dy
the eXperiments with either wood, iron, or steel \ per-
cptiDe set obtained with each material immediately
after the removed However small It's amount,
until the fell below the lowest possible determination OF
which apparatus capable VIZ l2OODOO OF an men,
The apartments were ordinarily COnlucl"d IoNst the
Largely increased aud ii found that the least per-
ccpblc immediate set still linicd only by the caa
billy the apparatus to detect minute dispacements
II take for tho limit Of elasticity Inc condition
OF things al which no permanent set Is obtained,
the case il differ ut. Thus IL found that the sct
whic subsist after the pine stick 8 inches by inches,
and feet long, had been loaded al its middle with 200
pounds q 10 Of breaking load, eventually passed off
entirely. This the whether the stress was mo
mcntary prolonged and whether II was applied Dui
practical limit elasticity exists but not theoretical
limit.
All the diverse phenomena Of set whether those which
have been under discussion As resulting from a
transverse those attendant upon direct tensile
or cumprcSSye STRESSED, determined by HolgkluSOu,
CheN aHdicr, and Werheim, and other rlmtuteS,
To conduct iniably 10 one conclusion TO one gene
raj conceptions in which alone they find their sufficient
explanation IL is universally admitted that all solid
bodies made mp OF ultimate molecules IN condition
equilibrium, either statical or dynanic under the
operation antagonlsc forces or attraction ana Iepu
son either actual virtual Now II l. plain that II this
true and IT, have the result Uf series
of increasing strains (by which the molecules are dis
tances), they take up series Of positions or rqnl
brium when the strains Withdrawn. differing by cX-
cessyely minute degrees from those previously occupied,
the effective forces eXercd by the molecules
other must suffer change Of Intensity viewing tho
residual spacement OF the molecules mechanical
problem constrained TO regard the elective mole
ciT forces, that take effect a gwen dist nct, as having
acquired din rent intensity either hrou shOut the BAR
at some more transverse sections.
read eore the Academy, Prof. Norton
gave new mathematical fOrmul,e for the detection Of
rectangular bars beams resting supports and sub
jccted Ia transverse stress.