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Full text of "Metallurgy Of Cast Iron"

CHAPTKR  I.XIV.
ROUND vs.  SylJAKR TEST BARS.*
The square test bar, east flat, was, prior to 1.890, almost s<>icl\' employed. The author first advocated the use <f a round test bar in an article in the American J/^r//////.v/, June 6, 1889. He is aware that the square bar, east flat, has been the basis of elaborate tables of transverse strength for use by engineers, etc., and for publication in our scientific text-books; yet, in spite of all this, the praetiee is \vron^*.
Metal, in cooling, arranges its crystals in lines perpendicular to the bounding planes of the mass, or, in other words, the erystals arrange themselves alon<r the lines I he waves of heat travel in passim;1 outward from the east in;,1, a,, it e<u!s oi'f. To assist in illustrating this subjeet I h,i\e taken the following description and cuts (Fiji's, inland i{)} frntn Spretsou's work on founding. Speaking of the eufs, Mr. Spretson says:
In tin- round lur Ihr rrystuls an* all radiating from the center.
In the ',|uarr  \>,ii tbry ai'r arranged per])eiulicular to the four t;iih-!i, am!  lirin/r h;tv<- four lines, in the diii^(mils of the square,
in whirh tf-n.nifi.il fil.iiirs of thf crystals iibtil or interlock, and ahonf wliirli t)i- r!"\".talH/,,'iti>ii is always confused and irregular.
This is said to be very plainly exhibited by the effect * A M'vi'-*-'! r\ir,!**? of a paptT na,d before the Western Foundry..
Iflt'It1'* A--'.' li? ioli,   I Sifif,   iH.j J,ould from head pressure are liable to make the area of the bars vary at different heights.on produced.