SL I
434
SOF
I
I
these ground-joists are themselves called sleepers. Oldwriters of practical architecture call those rafters which liein the valley of a roof by the name of sleepers ; but the word,applied in this sense, is quite antiquated : such rafters takethe name of the place under which they are disposed, that is,they are called valley rafters, or, more simply, valleys.
SLIDING-RULE, a rule constructed with logarithmiclines, formed upon a slip of wood, brass, or ivory, inserted ina groove, in a rule, made to slide longitudinally therein, sothat by means of another scale upon the rule itself, the con-tents of a surface, or solid, may be known. This rule hasalready been described under the article Carpenter's Rule :but as no examples of its use are given under that head, weshall here supply them. To make the matter more intelligi-ble, we shall here state that all squares are to be foundupon C, the side, and all roots upon d, the scale adjoining theslide next to the folding-joint; then, whatever value is puton the 10 on d, the value on c will be the square of thaton d. A mean proportional, or root, or given side, is to befound on D. The line C contains squares, lengths, and con-tents of solids. In finding a mean proportional, set the leastnumber on c to the same on d, then against the greater, onthe side, stands the mean on D.
Example 1. To multiply numbers together, as 12 and 16.—Set 1 on b, to the multiplier (12) on a ; then against themultiplicand (16) on b, stands the product (192) on a.
Example 2. To find the product of 35 and 19.—Set1 on B, to the multiplicand (35) on A ; then, because 19 on Bruns beyond the rule, I look for 1.9 on b, and against it, on A,I find 66.5 ; but the real multiplier was divided by 10, there-fore the product 66.5 must be multiplied by 10, which isdone by taking away the decimal point, so the product is 665.
Example 3. To divide one number by another , as 360by 12.—Set the divisor (12) on a, to 1 on b ; then againstthe dividend (360) on A, stands the quotient (30) on b.
Example 4. To divide 7680 by 24.—Set the divisor (24)on A, to 1 on b ; then, because 7680 is not contained on a,I look for 768 on A, and against it I find 32 on b, the quo-tient ; but because one-tenth of the dividend was taken tomake it fall within the compass of the scale A, the quotientmust be multiplied by 10, which gives 320.
Example 5. To square any number, as 25.—Set 1 upon cto 10 upon d. Then observe, that if you call the 10 upon d1, the 1 on c will be 1; if the 10 on d be called 10, then the1 on c will be 100; if the 10 on d be called 100, then the 1on c will be 10,000, &c. This being well understood, itcannot escape notice, that against every number on d standsits square on c.
Thus, against 25 stands 625against 30 stands 900against 35 stands 1225against 40 stands 1600
Reckoning the 10 on d to be 10.
Example 6. To extract the square root of a number .—Fix the slider exactly as in the preceding example, andestimate the value of the lines d and c in the samemanner ; then against every number found on c, stands itssquare root on D.
Example 7. To find a mean proportional between twogiven numbers, as 9 and 25.—Set the one number (9) on C,to the same (9) on d ; then against 25 on C, stands 15 on d,the mean proportional sought.
For, 1 : 15 : : 15 : 25.
Example 7. To find the mean proportional between 29and 430.—Set 29 on c to 29 on d ; and then 430 on c willeither fall beyond the scale D, or it will not be containedon c. Therefore take the 100th part of it, and look for 4.3
• mulMP 11
on c, and against it on d stands 11.2, which being 1by 10, will be 112, the mean proportional required - jSLIT DEAL, a name for incli-and-quarter-inc 1into two leaves, or made into two boards.
SMOOTHING PLANE. See Plane.
SNACKET, a local term for a kind of hasp f° r a ,j n<TSNIPE’S-BILL, a plane with a sharp arris for g el
ctd
<5
the quirks of mouldings.
carp«
SOCKET-CHISEL, a strong chisel, used byfor mortising ; used by the percussive blows of a n, ‘
ntei'S)
iecfi
of less ljeight than its horizontal dimension, serv-opedestals, or to support vases, and other orna® ensocle is sometimes continued round a building ° r
or imice-
■e p 1
flieenti re
ber
part of a building. It has neither base nor con*-- t ; n ,SOFFITA, Soffit, or Sofit, in architecture, a jjv g q t jar«ceiling formed of cross-beams, or flying cornices,compartments, or panels ol which, are enriched wture, painting, or gilding. the I ja,1 . n
The word is Italian, and signifies the same witn nCtr islacunar and laquear; with this difference, that focus!used for any ceiling with square hollow panels, caand laquear for compartments interlaced with- ? ' ja theafter the manner of knots, or laquei. Such are 1 1 ^ th e
basilicas and palaces of Italy , and in the apartmeLuxemburg at Paris , _ .^ e 0 f 6
Soffita, or Soffit, is also used for the un ,/g CU nar> ^corona, or larmier, which the ancients calledFrench denominate plafond, and we, usuallyi tf e [,, r eS> °*SOFFITS, the under sides of the heads of a P n a hoi -1 'the parts of mouldings which may be projected u f )tg 0 f tl>®zontal plane, by lines perpendicular from all Pj^ ve a [rea<ymouldings upon that plane. Several methods > ^r|,at J 3been described, under the article Envelope - piet lio 3proposed under the present head, is to show j n g the 1adopted by early writers, not with a view of exp eJ , roV eo°errors, but in order to guard the student ag alllsprinciples. , a „d 2, Bt
Figure 1, No. 1 and 2, as also Figure 2, jNo- j sli° vfrom Swan’s British Architect, Plate I.—■“ the *‘ ne g
the opening of a window in a straight wall. ^ ge m eet ’
ranging with the splay of the jambs; w . lier ®, e c iirva lu *' ^at a, is the length of the radius for drawing p,. 0 n) cthe soffit; then take the distance a b, trans e ^in Figure 2 ; then set your compasses ,n
in o,
width Of your >;
so# 1 ’ “'ill
this, when bent to a 3e
of 1,18
draw the external line ; tins, wnen -- jjrange along with each part of the straight w
“ Figure 2 represents the opening of a sm*”). t j,e
same width as the former, iri a circular wa • eI1 jng 0 0 [
semicircle above (Figure 2, No. 1) shows 1 111)11 fy 0 i"
arch. The arch-line may be divided in ° en dicul ar { j 10/ ),parts, as here, into twelve. Draw lines P e jj n e h< ^„\ t tthe base-line, through all these divisions o ^ a str^in Figure 2, No. 2, draw a circular line* ^ partswall; and divide it into the same num >et ( jj gta nces ,^ earch-line above Figure 2; then
same nut ^ ^
areii-nue uuuve j , .hen take 1 /y oal the v y 0 u
the line h to the circular wall, and set them t£) ]2; , v ijcflline in Figure 2, No. 2, as at 1, 2, 3, wine* 1 ’ c irc a '
will have the true curvature of your s0 ^ vV ith a
bent to a semicircle, will, in every part, »g pe-
- Join erS
Vf a*'" 6 .
pository^ by William Pain :— .
“ Figure 3 is a circular soffit in flewin D J ^ the P a n/flewing of the jambs, c d and ef, to -j are* 1 1then draw the arch df and divide the
lar wall.” , y a nd ■
The following are from the Carpe