dots and dashes, which indicate the letters of the
alphabet, after the manner of the Wheatstone sys-
tem.
Si'ren. An instrument for producing musical
tones and for measuring the number of sound waves
or vibrations jHn' second which produce a note of
given pitch. The production of these tympaniir
.shocks by puffs of air was hrst realized by Dr. Kob-
inson, and his device was the first and simplest Ibrm
of the siren. A stop-cock was so coiistructeii that
it opened and shut the passage of a }iipe 720 times
in a second. Air fnmi the wind-cliest of an organ
being allowed to pass along the pi[ie during the ro-
tation of tiie cock, a musical sound was smoothly
uttered.
It was much improved by Cagniard de la Tour in 1S27. who
gaveit its pn-sent uanie,and it has since been improved 1j\ Opell,
•Seebcck, and Dove In its original form it consists of a c_\liu-
drirnl box, into which a blast of air is introduced through an
aperture in the bottom, while the top is perlbnit*'d by a series
of equidistant apertures arranged in a circle. A circular plate.
(*iiiiilarly perforated, turns freely on its center, nearly in contact
with the top of the bo.\, alternately opening and closing the air-
passjiges in the latter. The apertures are fo inclined as to most
effectually impart a rotary motion to the di^k ; and when air
under pressure is admitted to the bo.\. its escape through the-«e
apertures produces musical tones rising in pitch according to
the velocity of the disk's rotation. ' The axis of the disk carries
a screw-thread, openititig a set of toothed wheels, by nuams
of which the number of revolutions made in a given lin.e i.s
shown on a .series of dials. This may be thrown in and out of
gear. When it is desired to a.'^certiin the number of impulses
per second required to produce a note of given pitch, the wind
pressure must be maintjiined at a uniform degree. The record-
ing appanitus is thrown into gear and allowed to run for a
given time ; when it is detjiched. the regi-«ter indicates the num-
ber of revolutions of the di-k, which, multiplied by the nuntber
of I'erforations, gives the total number of impulses ; this being
divided by the number of seconds during which the observation
wa-* made, shows the number of vibrations or souud-wuves per
second corresponding to the given pitch.
In the siren of Scebeck the rotation is produced by mccban.
ism, and not by the blast.
The double siren of Helmholtz consists of two sirens, one
placed in inverted position over tlie other.
The ujiper one may be rotated on its axis, Fig. 5113.
I while the instrument is in operation, by
: means of a crank. This instrument is adapt-
ed for the investigation of the interferences of
unequal sound-waves, of conibinatiou tones,
and many other acoustic phenomena.
In its most elementary form the siren is
simply a perforated rotating disk, agjiinst
, whic!) a current of air is directed, producing
: sounds of higher or lower pitch, according to
' the velocity of rot;ition The limits of audible Stren.
«ound are the rates of vibration of 16 and
38,000 in a .*^erond, which efiibrace more than II octaves; but
the range of effective musical sounds is much less. Thesoumis
I used in music are almost never lower than 32 vibrations in a
I Second (the lowest C on the piano-forte), thus comprising sevea
oct-ives.
I From the deep, piercing nature of the sound which the .=iren
emits, it is well adapted for fog signals or alaniis. In this case
I two di*ks rotating with great velocity in oppf site dinrtions aro
employed They are driven by a steam-engine, which also
j forces a blast of steam through their apertures, when tliose in
the 'wo di-<k^ come in apposition. The device is placed at the
' smaller extremity of a large trumpet, which intensifies the
sound The rare of rotation of the disks is ^about 1,UOO per
j minute, and the cost of the device i* about 1? 3,-'jl'0.
! The doctrine of the different sounds of vibnitiiig strings of
I diffi-reiit lengths, and the communication of sounds to the ear
by the vibration of the utmosphere, is ascribed to Pytlmgonis,
I about 500 B. c. : mentioned bv .\ristoile. S'H,) B. c : explained
by Galileo, a d liiOO : investigated by Newton, \'W.
" Discoursed with Mr. Ilooke about the nature of sounds, and
I be did make me undei'stand the nature of musical sounds made
SIEEN.
2191
SIZE.
by strings, mighty prettily ; and told me that having come to a
certiiu number of vibrations proper to make any tone, he is
able to tell how niauy strokes a fly makes with her wiiii^s, by
the note that it answers to in niusique. Tuis I suppose is a
little toj muclx refiued ; but his discourse in general of sound
was niigilty line.'" — 1*..pys* JJiiiry^ 1 j68.
It has been ascertained by means of the siren that the wings
of the niosiiuito move at the rate of 15,000 times a second.
An ingenious metliod of registeriu;; the vibrations of the
wings of insects was adopted by E. J. Marey, and is described
in the " Oomptes Rendus."
The author of the article sought for a mode of exhibiting, in
an unmistakable manner, each of the beats of the wing of an
Fig. 5114.
Steam-Sirfn,
in.<)ect, ani the graphic method answers very well for determin-
ing their frequency.
lie gnusped, with a fine pair of nippers, the hind part of the
abdomen of an insect, and wlien it souglit to tiy, directed one
of its wing* in such a way tliat it rubbed by its point against
the suffice of a smoked cylinder, which revolved with a known
velocity. The wing, at each of these revolutions, carried away
a little of the blick of the smoke wnich covered the cylinder,
and left a trice of its p;issige. This experiment gives a diagram
exhibiting the v.iried forms that are periodically reproduced
with the same rhirjicteristics, and. consequently, correspond to
one revolution of the wing. By means of a chronographic
diipason, the exact number of the revolutions of the wing
which are elTecte I in a, second were preciselv determined. That
which he used gave a graphic delineation of five hundred simple
vibrations per second.
A continu.al rubbing of the wing on the cylinder presents a
resistance to this organ, which retards its frequency ; so in or-
der to have the nearest approach to the truth, tho.se drawings
were selected in which the contact of the wing with the cylinder
Fig. 5113.
tiy, 330; drone, 240 ; bee, 11)0; wasp, 110 ; hawk-moth, 72 j
dragon-Hy, 28 ; cabbage-buttertiy, 9.
Experiments with tne siren show that the extreme limits of
the human voice in males vary from 3S4 to 1,'26» vibnliuns per
sei-oiid,aud in ieinales fritm 1^1.J2 to 3,'.:40. Tne hi^'hesl note in
music is about the 14th (five oct ive- above tlie mid lie C of the
Jiiauo-forle , and this is due to S,lJ2 vibratious per seioiid ; but
much higller tones can still be heard. Savart has produced
tones due to 48,000 vibrations per second.
Sir'up-staad. An ;itt;tLliiiii'iit to a soda-naU'f
aiii«iotii.s, to Mipjily the tuiiiliU-r.s witli sini]i.s. Some
have faucet.-i connecting with tlie .separate siriip ves-
.ervoirs; others have pistons acting as niiiii;iture
jininps. In the e.xaniple, tlie cii.se lias a liingeil
cover, kept in place by piojection.s, ami con-
tains earthen siinp-jars ami a cooling-chaniher
for the soda-water, each snrrouiuh-d by ice.
The siraji-faucets are lined with gla.ss, and
secnred to the jars by a screw and rubber
packing.
Sis'ter-block. (Xautica!.) A kind of
double block which has two sheave-
liolcs, one aliove the other ; a score at Fig 5116.
e;ich end, and one between the sheaves.
It is used as a topsail-lilt and reef-
tackle block, and is hollowed out on
each side of the shell, so as to lay be-
tween the shrouds. The name is from
citlin-n, signifying iis, fiddle shape.
Sis'ter-hook. A double hook in
which the shanks of the respective
])ortions form mmsingx for the fellow
portions. A malch-liook. See Muus-
?* lN(;-iio()K.
Sis'ter-keel'son. (SliijtbuUdiiiri.) An a 1-
ditional keelson .secured on eaidi side of and
parallel to the main keelson. The sister-keel-
sons are bolted to the lloor-tiinbeis. A side keel-
son.
Sis'trum. {.Viisic.)
ancient ligypt. It
had four loose rods
A jingling instrument of
Fig. 6117.
SiritpSland.
yns at a minimum, so that the diagrams were reduced to a
series of points. The following results were obtained ; Common
SUtnim.
in a lyre-shaped me-
tallic head. It was,
ill fact, a rattle made
of bronze or silver,
according to ability.
It w.as used in the
services of I sis or
Athor, which were
introduced into
Home before the
(.'hristian era. It is
still used in Chris-
tian chun.'hes in
Nubia and Abys-
sinia.
Sitz-bath. A hip-bath in which a person as-
sumes a sitting posture.
Six-shoot'er. (Waipmi.) A colloquial name
for the six-chambered revolver.
Size. 1. A gelatinous stdution made by boiling
the skill and membraneous tissues of animals to a
jell.V-
The finest is made in Russia from the sonnds and
air-bladders of .sturgeon, and is called iximj'nus.
A coarser quality is made from scraps and clip-
pings of hides, hoofs, horns, etc., and the jelly or
size resulting is molded, cut into Hakes, aud dried,
forming glue.
A ([uality made from clean scraps of the above-
mentioned material is sold as isinglass, which it
nearly resembles.
Bones and feet of animals al.so yield a glutinous,
viscid solution or jelly, which may be considered a
1 size.
SIZE-UOX.
2192
SKATJi-GRINDER.
Fig. 5118.
Size-Bo£.
Size is used in culico-iiriiitin;;, paper-iimkint;, iiaper-lmiiKint;.
bodkliiiiJintJ, wliitt:\vn.sliiiig, icutUiiig.giMiuj^, :iud iit other urtd
and tiiuk'M,
In some ciL^L's, it stniid' in tlif pUuv of ur i.> usi'd iiitL'rfh;inge-
abiy witli tlf.rtnnr or Itriiisli ^"'"1 P":*'^'. st;irfli, j;mn-wjiter.
vitnii"ih, nr otIiL'P visL'id Kolutioii, wtuh-u |»irticlus become liurd
wlii'ii tlieir water of solution evaporates.
'rin'"-i/,i'.''U8«;d in j;ildinKiire;is follows: mild-size
lor itil'iiiiilini:, linsL-eil-oil or fat oil and ocher
That wsvil tor huinis/i-^ildiiit; is t-oniposcd of
pipe-oiay, red chalk, bluck-lead, sui't, bullock's
blood, brought to a. proper cousistencc by a solu-
tion of ;;i'latinc
HiHikliinder's size is a fine gluu made of parch-
ment shavings. Anotlier material used by the
gilder is ^laire, white of egg.
2. A ^;ix»' loi" iHLMsiiriii^. An iiistni-
iniMit tor ini'iisuriiig ])cavl.s. A lunnljcr
of pcitur;iti'd gagcy :irii iusteiicd togetlicr
Ity a rivet at one end.
Size-box. {Hope- making.) One tiiroiigli whicli
itordage is drawn in the process of
sizing. The eordage liaving been
drawn tln-ough tlie size-box and
|iarlially dried is drawn shiwly
betwi-en r.losely pressing rei'ipro-
oating I'nhli'us and sattrjijcrs, wliieli
are stationary relatively to the
slowly moving carriage to which
they are attaiilifil. Tlie size is Hour-paste mixed
withtttiicr ingredients, and the operation on tlie rope
is called sinKjijiiKj, dick'iiKj^ ov Jinishimj. It smooths
down the sicexif and//(.:r// libers of the twisted rope.
Si'zel. {(h)huiiij.) Strips of metal from wliieh
planehets have been ienii)ved. HdsscL
Siz'er. 1. A machine of perforated plates to sort
articles of varying sizes, as the coffce-sizers of Geylou
ami liio.
2. A gage, as the huUct-sizcr, whiLh has holes to
deterr)une the sizes of bnllets. See also Siikll-gagk.
Size-stick. The shoemaker's measuring-stick to
dcri'niiiiic till' Icngtti of feet.
Siz'ing. A glue or paste used in manufactures.
Sec SizK.
Siz'ing-ap'pa-ra'tus. {Mini it (j.) Machinery
for sorting ore into grades according to size, for
treatment l)y the appropriate means.
Haad-sic'vcSy swiny-.sieirs, and shtlcinij and cylin-
drical riddles are the usual means employed.
.ligging-sicves are not for sizing, but for sorting by
gravity. Sei- ,Iii:t;Ki:.
" ' " ' ' A form of ore-separator which
a(!ts upon the metalliferous
slime from the staniping-
nrill.
Tt consists of ft wooden box,
having an opening c at the bot-
tom, wliich communicates with
il pi'i"*sin'e-pipe b and an outlet c
provided with a small regulating
sbiire '/. The lighter stulf from
the hudclle-t e. is carried upward
and conducted otf by the open-
ing t\ while the heavier descends.
Tho strength of the upward current, and consequently the
quantity and size of the particles conveyed away at/, is regu-
lated by opening or closing the slaicu d.
Siz'ing-ma-
chine'. Anai)pa-
ratus for sizing
cotton warp-
tln<'atls.
The trough n is
provided with a stetun
jacket, and contains
a number of rollers b
li\ etc. ; it is nearly
filled with liquid
p.iste, and the warp
is drawn alternately
under one uud ovi-r
another of the rollers
until it pJisses between
I the rolls (â– e', which express the superfluous pjiate. For woolen,
u sizing of glue U emp.oyed The yarn is drawn bui-kward and
I forward through trumpet-siiaiicd openings, and pai<=e» beneath
, H roller at e:u:h end of the bo.\ ; repeated eompression and iin-
i nierf^ion is necessary to expel the air auii s.i,turate the fiber.
I Fig. tjl2I is a maehiue for sizing and fiuishiug covered skirt-
Fig. 5121,
Sizlug-cis'tern.
Fig. 5119.
Siztii:
Fig, 5120.
Wire-Sizing Machine.
wire. The wire is passed through the starch or size, and
thence directly in contact with ironers or polishing surfaces,
whence it may be passed over rolls and heaters previous to its
being reeled.
two surfaces by
Fig. 5122.
aiziii^'Iil't'/itne.
S-joint. A mode of joinin,
means ida doubly bent strip,
S-siiaped ill cross-section.
Skain. 1. A shaved .s;j/d7
of osier. A split is a (pnir-
tcr of the osier, divided lon-
gitudinally down the pith.
2. {SjiinuijKj.) A knot of
yai'U. See Skkin, 1.
3. {Vehicle.) A strap or
tube of metal on the arm of
a wagon-axle. See Skein, 2.
4. (If-'capon.) . An Irish
short-swtud. A skcau. \ S-Joint.
Skate. I. A runner fas-
tencil to the boot-.sule, by wliicli a person may pro-
pel liiniself upon the ice.
2. In an in-door sport suggested by skating, the
sole has rollers instead of a runner. A parlor -akatc.
Fitz-Stephen informs us that it was customary for the Eng-
lish, in the thirteenth century, to amuse themselves on the ice
by fiist^-ning bones of animals to the soles and pushing them-
selves forward by means of a stick, shod with an iron spike.
Wooden skate-, shoil with iron and steel, were introduced into
England from the Netlierlaikls. about lb50.
" It being a great frost, did see people sliding with their
skeates. which is a very pretty art." — Pepys' Diary, Novem-
ber. I()ii2.
Fig. 5123 illustrates various recent patterns of skates, witli
their modes ofattachment to the shoe
a may be arranged so as to be secured either by clamps or
straps.
b is secured by adjustible clamps.
r is fastened at the heel by three spurs, adjustable by a screw,
a strap being employed for the front.
d by a lip at the toe, and a clamp, moved backward or for-
ward by a screw, ut the heel.
e lias toe and heel damps, which are caused to approach or
recede by a screw.
/, the skate-iron is pivoted and provided with a spring, so
that the heel and toe elauips are opened by releasing and de-
pressing the iron ; by placing the foot on the sole-plate and
raising the iron, the i-lamps are caused to close upon the shoe
and secure the skate.
§ ha*t two runners, connected by a flexible strip, wliich yields
to the movements of the foot.
/( is a parlor-skate constructed on the same plan.
I is a parlor-skate in which the rollers are tiistened in hangers
beneath the sole : runners may be substituted for the hangers.
Tho skato {a. Fig. 5124) is se<'ured to the boot by a pin with
pointed enlargeil end in the heel plate, and a strap passing
through the sole-plate and over the foot .
In h both the heel and sole plates are divided longitudinally,
one of each being hinged : the clamps ai-e adjustable to the
width of the foot, and are, when fixed to the boot, held by the
pressure.
Skate-grinder. A machine for griniUng skates,
straiglit-edged or rockers.
The loose skate-holder and the table have each a plane or
l)eveldiearing surface, forming, when resting on each other, two
i-(u-rcsponding plane or bevel surfaces. The rotury grinding-
whcel dresses the running edge of the blade. The holder 18
SKEAN.
2193
SKELP.
6123.
Fig. 5125.
attached with a^justahle clamps, and has rests for securing the
work.
Skean (Irish, Scian). (IFeapon.) An Irish
Fig. 5124.
Florence Skates.
weapon. A large knife molded like a sword. A
tkain.
138
Skeet. (Xinitkul.) A
scoop used for throwing
water on the sails and
dei.'ks.
Skeg. (Bntit-building.)
A knee which unites and
braces the stern-post and
keel of a boat.
Skein. 1. (Sjnnninri.)
A ([iiantity of yarn fmui
the reel, of silk, wool, cot-
ton, or flax. Of cotton
it contains 80 threads of
oi inches ; 17 skeins make
a hank ; 18 hanks a spin-
dle (Englisli). See also Hank.
The word skein is derived from the Greek word rrxolvo^
rope or urush ; indicating the material from which the ropes
Egypt were formerly made.
2. {Vehicle.) A metallic strengthening band
thimble on the wooden arm of an axle.
Fig. 5126.
Sknle- Grinder.
Tliimble- Skein.
The ordinary skein consists of three straps, let
into slots in the arm.
The tkimble-skein is a conical metallic sheath which envelops
the wooden arm , and lias a Hanged nut on the end to hold the
wheel on the arm. See A.xle.
Skel'e-ton-frame. (Spinning.) A kind of frame
in whicli tlie usual can is replaced by a skeleton.
Skel'e-ton-key. A key of skeleton form, a
large yiortion of the web being removed to adapt it
to avoid the wards and impediments in a lock. See
Ma.stf.r-key.
Skel'e-ton-plow. (Agriculture.) A plow in
which tlie parts hearing against the soil are made in
skeleton form to lessen friction. See Plow.
Skelp. A strip of iron which is heut and welded
into a tube to form a gun-barrel, or pipe.
Skelps for gun-barrels were formerly forged, the strip being
about 3 feet long and 4 inches wiile, thicker at the end for the
butt than at the end which forms the muzzle. These skelps
were afterward bent, lapped at the edges, and welded at several
heats.
These forging operations were superseded some years since at
Birmingham, England , by rolling processes, which have become
general.
For rolling, the circumference of the roller is equal to the
length of the skelp, and the shape of the groove is adapted in
width and depth to the width and thickness of the skelp
Welding w.as performed by running the skelp with lapping
edges througli the circular aperture formed by the semicircular
grooves of adjacent rollers. The skelp was brought to a welding
heat and placed on a mandrel
This plan has been modified by m.^king a blank of an extra
thickness and combining a drawing and welding action.
SKELP-BENDER.
2194
SKEW-PLANE.
A bar of iron about a foot long is bent into a cylindrical shape,
the edges overlapping ; being raised to a welding heat, it is then
slipped over a triblet and iw^ssed between a pair of rollew, which
weld the edges and draw the cylinder to the length and propor-
tions of a gun-barrel at a single heat.
Skelp-bead'er. A die of retjuired form is made
ill two parts, so arranged on a slide as to oiieii for
the admissiou of tlie eud of the sheet aud be closed
Fig. 5127
Si:dp-Benditig Madiine.
by a lever. The end is then bent up, when it is
seized by the proper apparatus and drawn through
the die.
Skene-arch. (Architecture.) A segmental arch
havin<^ a ciuve not exceeding 180°.
Skep. (Hasbaiulry.) a. A farmer's basket for
gathering corn or roots.
b. \ bceliive ; a jum.
Skew. A term applied to an arch, vault, or
bridge iii which the front of the arch is oblique with
the face of the abutment, instead of being at right
angles thereto.
As originally built, the voussoirs were laid parallel to the
abutments. In 1787, Chapman, in constructing a bridge over
the Kildare Canal, Wiis led to the invention of the correct prin-
ciple, making the joints of the voussoirs rectangular with the
fece of the arch instead of being parallel with the abutments.
Skew-arch. (Architecture.) One having its
faces oblii[ue to the piers or abutments.
Skew-back. (ArchitectHre.) a. The upper course
of an abutment which receives the spring of an arch.
An iiiijxist.
b. A Ijedding-stone.
Skew-bev'el Wheel. (.Vachincri/.) A form
of wheel employed to
transmit a uniform ve-
locity ratio between
two axes which are
neither parallel nor in-
tersecting. Tlie pitcli
surface of a skew-bevel
wheel is a frustum or
zone of a hyperboloid
of revolution. In one
of the figures (B), a
pair of large portions
of such hyperboloids
are shown rotating
about axes a b c d. In
the other figure are
shown a pair of narrow
I N^ I ,• zones of the same fig-
^/^Jr ures, such as are e\a-
Slceur-Oearinsnnil Skm-Bevel ploved in practice.
w/ieeu. Skew-bridge.
(Architcdurc.) One
liaving an obliipie arch or arches with spiral courses.
Ske-w-chis'eL 1. A chisel for wood working or
turning, liaviug the basil on both sides and an oblique
edge.
2. A carver's chisel, whose shank is bent to allow
the edge to reach a sunken surface.
SkewT'er. 1. {Fiber.) A bobbin-sj)iudle fi.xed
liy its lihuit end into a shelf or bar in the creel.
" 2. A siiindle-shaped piece of wood inserted into
meat, to liold tlie layers of muscle or muscle and fat
together.
SkeWer-ma-chine'. The blocks are sawed into
little slabs of the size
and double the Fig. 5129.
length of the skewer
desired. They are
tlien passed through
a machine, which
shapes them into lit-
tle cylinders, looking
like unpointed lead-
pencils. The ma-
chine has a grooved
endless floor-
feeder, and a revolv-
ing grooved feed-
roller and cutters,
whicli are shaped to
cut the cylindrical
shape of the skew-
er. They are now
ready for sharpen-
ing.
Fig. 5130 IS a ma-
chine to point, cut
to a length, and count the skewers after they have
been made round. The sticks, of double skewer-
length, are fed
S/cewer- Machine.
from a hopper
into a grooved
cylinder, which
presents them
to a revolving
cutter that
points each
stick, and cuts
in two at the
center, and at
the same time
is cut to a length
by two revolv-
ing saws on the
same shaft with
the cutter. Not
Fig. 5131.
Fig. 5130.
Skew- Gearing
Skewer-Pointing Machine.
until fifty are completed does the machine drop them
into the" pan below, from whence the bunches are
taken and deposited in a tray preparatory to their
transfer to tile drying-vooni, the skewers being made
from unseasoned wood.
Skew-gear'ing. Cog-wheels with teeth placed
obUi|uely, so as to slide into each other and avoid
clashing. They serve to transmit motion from one
shaft to another when the two fonn an angle, but
wofild not intersect if prolonged. A, Fig. 5128,
SKEw-iir.vr.i, WuEF.L.
Skew'ing. (Gilding.) The process of removing
superfluous leaf from portions of a surface and patch-
ing pieces upoii spots where it has not adhered. It
is perfonned by means of a brush and precedes bur-
nishing. See Gilding.
Skew^-plaue. (Joincrij.) One in which the
SKEW-RABBET PLANE.
2195
SKIX.
mouth of tlie plane and the edge of the iron are
obli(iuely across the face.
Skew-rab'bet Plane. {Joinery.) A plane for
cutting rabliets ; the edge of the bit obliquely across
the .sole of the jilaue.
Skew - wheeL See Skew-bevel Wheel.
Skid. 1. (Xaidical.) a. A strut or post to sus-
tain a beam or deck, or to throw the weight of a
heavy object upon a part of the structure aide to
bear the burden.
b. A pair of timbers in the waist, to support the
larger boats when aboard.
c. Timbers acting as fenders against a ship's side
when raising or lowering heavy bodies inboard or
overboard.
2. Slanting timbers forming an inclined plane in
loading or unloading heavy articles from a truck or
wagon.
3. Timbers resting on blocks on which a structure
is built, such as a boat.
i. (Ordiumix.) An oaken timber 6 feet long by
8 inches square, used for the temporary support of a
cannon. These and the other iuij)lements are all
made to given sizes witli reference to their more
convenient use and transportation together.
Skids of cast-iron are used for supporting cannon
in store at the arsenals.
Fig. 5132. 5. A cliaiii with a shoe
to drag a wheel.
6. A log, forming a
track for a heavy moving
object.
7. {Crane.) An iron