S T E
443
S T E
# - Hardened steel has less specific gravity
1 { he soft. The texture of steel is rendered more uniform
tli'5 lts ^acture be.
r ai > ti,
tiy f .
USln g it before it is made into bars, and in this state it is11 Cast stee ^> which is wrought witli more difficulty thanU„ ( ] t,lon steel, because it is more fusible, and will dispersethe hammer if heated to a white heat.
*lti species of iron is convertible into steel by cemen-ijf.jt n ’ ^t the best steel can be made only from iron of thet " a ll flUa,it y, which possesses stiffness and hardness as well asWstT bilit 7- Swedish iron has been long remarked as the•|,| 0r this purpose.
^bi
He
'out
cast steel of England is made as follows : a crucible,
e 11(ls ; ten inches high, and seven in diameter, is filled witht f n< ^ fragments of the crude steel of the manufactories,tl le le filings and fragments of steel works ; they add a flux,J>rob °.®P on ent parts of which are usually concealed. It ist)p Q(l * le > however, that the success does not much dependthat r ® ux> Ehis crucible is placed in a wind furnace, like1 the founders, but smaller, being intended to contain
Oul
y on e
"‘Oase hot, and surmounted by a cover and chimney to in-Mtp 6 l | le draught of air; the furnace is then entirely filledthe r, p e > or charred pit-coal. Five hours are required for®qn aj , l ‘ ec t fusion of the steel. It is then poured into long,Cast.; 0r octagonal moulds, each composed of two pieces ofI 0n fitted together. The ingots, when taken out of thelr, t '
Sa me
oulj i o- -—o —’ —
' n ave the appearance of cast-iron.
It is then forged
y 0 f e manner as other steel, but with less heat and
!oo(j i <le caution. Cast steel is almost twice as dear as other! it is excellent for razors, knives, joiners’ chisels,l c^tu r . n fis of small work requiring an exquisite polish: its
if,* 6 . 13 more uniform than that of common steel, which is■ n fil ; Ui(]^bl e advantage. It is daily more and more used in
i fiiti
i j
Uij e '> fiat it cannot be employed in works of great mag-: fj r ’ 0n account of the facility with which it is degraded inS’pg’ a,1( l the difficulty of welding it.
V ^LE, a spire or lantern; the pyramidal roof of a8 Mre ’ , y some the term is made to include both tower and
tvi tl ’ and by others is used indifferently for any lofty tower,ST^ ith °ut a spire.
' :ftlllv ia f 1 ERAP, a valve to prevent the emission ofSTEps? 01 ficains and sewers ; they are of various forms,u (from the Saxon, steep,) the degrees of a stair-*1 caij ' v fiich we rise, consisting of two parts, one horizon-! i t - PlaceV^*: the other vertical, called risers. When stepsor eci r °und the circumference of a circle, or of an ellip-^segments of them, they are called winders: butt r W et . e Sl< Es are straight, they are called flyers. The first,° nl Ste ^’ Wlt * 1 a scr °fi wrought upon its end, according. ^’I'prf,'! °f the hand-rail, is called the curtail step,
REobata
>!„?>,) 1A ’
'h.'eotta - •
of 8 a.ns\ Co Umn > wall, or other piece of building, is raised.I l be *7* pretty well to the continued socle, or basement1 oT Q ’ °f Some confound it with the ancient stylo-
Oo] E, vyj ' stc ‘l! hut, in effect, the stereobata is to the sty-lat l hc stylobata is to the spire, or base of the
^GRAPHIC PROJECTION of the SPHERE,r °f ti, VVaic ^ the eye is supposed to be placed in the sur-
^fesphere. J ™
i pGliAPIIY, ('from veoeoc, solid, and ypadxo, to
or Stekeobates, (from v£p£o/3ari)c,tn ancient architecture, the basis, or foundation,
Pfi
) that
'operf"" * 3ranc h °f solid geometry which demonstratesV^SfPi l' 68, a "fi shows the construction, of all solids which’<> su r |^ ^filled. It explains the methods for construct-ive,. ^aces in planes, so as to form the entire body, orHid ^ e surface of a given solid ; or, when a solid isy plane surfaces, the inclination of the planes is
determined by the rules of stereography. The sectionsof solids are also a branch of stereography ; but we shall treatof them in the article Stereotomy, with which they aremore intimately connected.
Mr. Hamilton has denominated the principles of perspec-tive by the name of stereography ; but in this sense the termis too limited, as perspective is only a branch of the doctrineof solids, and extends only to the sections of pyramids andcones, and the representations of solids.
The eleventh and twelfth books of Euclid , which treat ofthe properties of solids, may be looked upon as the elementsof this branch of geometry; and to them we shall refer ourreaders for the first elements to be acquired.
It is somewhat singular, that though the first principles ofsolids have long been demonstrated, no practical applicationto mechanical constructions has been made of them. Theknowledge of solids is of the greatest importance in the con-structive parts of architecture, as in masonry, bricklaying,carpentry, &c.
To be proficient in the art of construction, this branch ofgeometry is indispensable, and contains the very essence andfoundation of the whole in abstract.
Definition 1. —A solid is that which has length, breadth,and thickness.
Definition 2.—The exterior surface of a solid is called itssuperficies.
Definition 3.— A straight line is perpendicular, or at rightangles to a plane, when it makes right angles with everystraight line meeting it in that plane.
Definition 4.— A plane is perpendicular to a plane, whenthe straight lines drawn in one of the planes, perpendicularlyto the common section of the two planes, are perpendicu-lar to the other plane.
Definition 5.— The inclination of a straight line to a planeis the acute angle contained by that straight line, and anotherdrawn from the point in which the first line meets the plane,to the point in which a perpendicular to the plane drawn fromany point of the first line above the plane meets the sameplane.
Definition 6.— The inclination of a plane to a plane is theacute angle contained by two straight lines, drawn from thesame point of their common section at right angles to it, oneupon one plane, and the other upon the other plane.
Definition 7.—Two planes are said to have the like incli-nation to each other, which two other planes have, when thesaid angles of inclination are equal to one another.
Definition 8.— Parallel planes are such as do not meeteach other, though produced.
Definition 9.— A solid angle is that which is made by themeeting of more than two plane angles, which are not in thesame plane, in one point.
Definition 10.— Similar solid figures are such as have alltheir solid angles equal each to each, and contained by thesame number of similar planes.
Definition 11.— A prism is a solid, of which the ends aresimilar and equal plane figures, and the sides parallelo-grams.
Definition 12.—When the ends of the prism are perpendicular to the sides, it is called a right prism; but if other-wise, it is termed oblique
Definition 13.—A prism, whose sides and ends are equalsquares, is called a cube.
Definition 14. —When the ends are parallelograms, theprism is called a parallelopiped; and when the plunes of theparallelopiped are at right angles to each other, the prism iscalled a rectangular prism.
Definition 15.—When the ends of the prism are circles, it