_f_, mounted upon the same axle, and it takes into geer with a pinion
_g_, upon the main shaft _h_, which is actuated by a band passed from
any first mover to the rigger on its end, or in any other convenient
manner. The bed upon which the blank piece of steel bears is marked _i_.
This bed is firmly supported upon masonry placed upon proper sleepers:
_j_, is one of the blank pieces of steel under operation, and is shown
secured in the pair of jaws or holding clamps _k_, mounted on centre
pins in the slide _l_, _fig._ 385.; which slide is held down by a spring
and slide beneath, and is moved backwards and forwards in the machine
upon the (v) edges _m_, _m_, of the frame, by means of the rack _n_, and
its pinion; the latter being mounted upon the axle of the ratchet wheel
_p_, and which ratchet wheel is made to turn at intervals by means of
the pall _q_, upon the end of the lever _r_, _fig._ 385. This lever is
depressed, after every cut has been effected upon the blank by means of
the teeth or tappets of the wheel _s_, coming in contact with the
inclined plane _t_, upon the lever _r_. The tappet wheel _s_, is mounted
upon the end of the axle _e_, of the tilt wheel, and consequently
revolves with it, and by depressing the lever _r_, every time that a
tooth passes the inclined plane _t_, the click _q_, is made to drive the
ratchet wheel _p_, and thereby the advancing movement of the blank is
effected after each blow of the tilt hammer.
There is a strong spring _u_, attached to the upper side of the tilt
hammer, its end being confined under an adjustable inclined plane _v_,
mounted in the frame _w_, which inclined plane can be raised or lowered
by its adjusting screws as required, to produce more or less tension of
the spring.
A similar spring is placed on the under side of the tilt hammer, to
raise and sustain the cutter or tool clear of the bed after every blow,
and in conjunction with safety holders or catchers, to counteract any
vibration or tendency the spring _u_, may have to cause the hammer to
reiterate the blow.
The end of the lower spring acts on an inclined plane, mounted in the
frame _w_, which has an adjusting screw similar to _v_, to regulate the
tension of the spring.
In case the under spring should raise, that is, return the hammer, with
sufficient force or velocity to cause the top spring _u_, to reiterate
the blow, the ends of the safety holders or catchers are made to move
under and catch the tail of the lever _b_, immediately on its being
raised by the under springs, which is effected by the following
means:--The holders are mounted upon a plate or carriage 1, _fig._ 384.,
which turns upon a small pin or axle mounted in the ears of a cross bar;
the upper ends of the holders are kept inclined towards the tail of the
tilt hammer by means of a spring fixed to the cross bar, and which acts
upon one end of the plate or carriage 1.
In order that the holders may be removed out of the way of the tail of
the hammer _b_, when the tilt wheel is about to effect a blow, the tooth
of the tilt wheel which last acted upon the hammer comes in contact with
an inclined plane fixed on the plate or carriage 1, and by depressing
that end of the plate, causes the upper ends of the holders to be
withdrawn from under the tail of the hammer _b_. The tilt wheel
continuing to revolve, the next tooth advances, and depresses the tail
of the hammer, but before it leaves the tail of the hammer, the tooth
last in operation will have quitted the inclined plane and allowed the
spring to return the holders into their former position. After the tooth
has escaped from the tail of _b_, the hammer will immediately descend
and effect the blow or cut on the blank, and as the tail of the hammer
rises, it will come in contact with the inclined planes at the upper
ends of the holders, and force them backwards; and as soon as the tail
of the hammer has passed the top of the holders, the spring will
immediately force the holders forward under the tail of the hammer, and
prevent the hammer rising again until the next tooth of the tilt wheel
is about to depress the end of the hammer, when the same movements of
the parts will be repeated, and the machine will continue in operation
until a sufficient length of the blank of steel (progressively advanced
under the hammer) has been operated upon, when it will be thrown out of
geer by the following means:--
Upon the sliding bar 6, there is placed an adjustable stop, against
which the foremost end of the slide _l l_, _fig._ 385. comes in contact,
as it is moved forward by the rack _n_, and its pinion. The sliding bar
6, is connected at its left end to the bent lever 8, the other end of
this lever being formed into a forked arm, which embraces a clutch upon
the main shaft, and as the slide _l_ continues to advance, it will come
in contact with a stop; and when it has brought a sufficient length of
the blank pieces of steel under the operation of the cutting tool, the
slide _l_, in its progress, will have moved that stop and the bar 6
forward, and that bar, by means of the bent lever 8, will withdraw the
clutch on the main shaft, from locking into the boss of the fly-wheel,
and consequently stop the further progress of the machine; the rigger
and fly-wheel turning loosely upon the main shaft.
The cut file can now be removed from out of the clamps, and reversed to
cut the other side, or another blank piece put in its place; and after
throwing back the pall _q_ of the ratchet wheel _p_, the slide _l_, and
with it the fresh blank may be moved back into the machine by turning
the winch handle, on the axle of the ratchet wheel _p_, the reverse way,
which will turn the pinion backwards, and draw back the rack _n_,
without affecting any other parts of the machine; and on moving back the
bar 6, by the handle 11, placed on the stop, the clutches will be thrown
into geer again, and the machine proceed to cut the next blank.
When the blanks have been thus cut on one side, and are reversed in the
machine to form the teeth upon the other side, there should be a piece
of lead placed between the blank and the bed to protect the fresh cut
teeth.
It will be seen that the position of the stop upon the bar 6, will
determine the length or extent of the blank piece of steel which shall
be cut or operated upon; and in order that the progressive movement of
the blanks under the cutting tool may be made to suit different degrees
of fineness or coarseness of the teeth (that is the distance between the
cuts), there is an adjusting screw upon the lever _r_, the head of which
screw stops against the under side of an ear projecting from the
frame-work, and thereby determines the extent of the motion of the lever
_r_, when depressed by the tappets of the wheel s, acting upon the
inclined plane _t_, consequently determining the number of teeth the
ratchet wheel _p_ shall be moved round by the pall _q_; and hence the
extent of motion communicated by the rack and pinion to the slide _l_,
and the blank _j_, which regulates the distance that the teeth of the
file are apart, and the lever _r_ is forced upwards by a spring pressing
against its under side.
It will be perceived that the velocity of the descent of the hammer, and
consequently the force of the blow, may be regulated by raising or
lowering the inclined plane _v_ of the spring _u_; and in order to
accommodate the bed upon which the blanks rest to the different
inclinations they may be placed at, that part of the bed is formed of a
semi-globular piece of hardened steel, which fits loosely into a similar
concavity in the bed _r_, and is therefore capable of adjusting itself,
so that the blanks shall be properly presented to the cutting tool, and
receive the blow or cut in an equal and even manner; or the piece of
steel may be of a conical shape, and fit loosely in a similar shaped
concavity.
There are guides 16, placed on the top of the bed _i_, for the purpose
of keeping the blanks in their proper position towards the cutting tool,
and these can be regulated to suit blanks of any width, by turning the
right and left handed screw 17. There is also another adjustable stop on
the jaws or clamps _k_ which serves as a guide when placing the blanks
within the jaws: and 19 is a handle or lever for raising the clamps when
required, which has a weight suspended from it for the purpose of
keeping down the blanks with sufficient pressure upon the bed.
The cutting tool in the face of the hammer, can be placed at any
required angle or inclination with the blank, it being secured in the
head of the hammer by clamps and screws. In cutting fine files a screw
is employed in preference to the rack and pinion, for advancing the
slide _l_, and the blank piece of steel in the machine.
_Hardening of files._--This is the last and most important part of file
making. Whatever may be the quality of the steel, or however excellent
the workmanship, if it is not well hardened all the labour is lost.
Three things are strictly to be observed in hardening; first, to prepare
the file on the surface, so as to prevent it from being oxidated by the
atmosphere when the file is red hot, which effect would not only take
off the sharpness of the tooth, but render the whole surface so rough
that the file would, in a little time, become clogged with the substance
it had to work. Secondly, the heat ought to be very uniformly red
throughout, and the water in which it is quenched, fresh and cold, for
the purpose of giving it the proper degree of hardness. Lastly, the
manner of immersion is of great importance, to prevent the files from
warping, which in long thin files is very difficult.
The first object is accomplished by laying a substance upon the file,
which when it fuses, forms as it were, a varnish upon the surface,
defending the metal from the action of the oxygen of the air. Formerly
the process consisted in first coating the surface of the file with ale
grounds, and then covering it over with pulverized common salt, (muriate
of soda.) After this coating became dry, the files were heated red hot,
and hardened; after this, the surface was lightly brushed over with the
dust of cokes, when it appeared white and metallic, as if it had not
been heated. This process has lately been improved, at least so far as
relates to the economy of the salt, which from the quantity used, and
the increased thickness, had become a serious object. Those who use the
improved method are now consuming about one fourth the quantity of salt
used in the old method. The process consists in dissolving the salt in
water to saturation, which is about three pounds to the gallon, and
stiffening it with ale grounds, or with the cheapest kind of flour, such
as that of beans, to about the consistence of thick cream. The files
require to be dipped only into this substance, and immediately heated
and hardened. The grounds or the flour are of no other use, than to give
the mass consistence, and by that means to allow a larger quantity of
salt to be laid upon the surface. In this method, the salt forms
immediately a firm coating. As soon as the water is evaporated, the
whole of it becomes fused upon the file. In the old method the dry salt
was so loosely attached to the file, that the greatest part of it was
rubbed off into the fire, and was sublimed up the chimney, without
producing any effect.
The carbonaceous matter of the ale grounds is supposed to have some
effect in giving hardness to the file, by combining with the steel, and
rendering it more highly carbonated. It will be found, however, upon
experiment, that vegetable carbon does not combine with iron, with
sufficient facility to produce any effect, in the short space of time a
file is heating, for the purpose of hardening. Some file makers are in
the habit of using the coal of burnt leather, which doubtless produces
some effect; but the carbon is generally so ill prepared for the
purpose, and the time of its operation so short, as to render the result
inconsiderable. Animal carbon, when properly prepared and mixed, with
the above hardening composition, is capable of giving hardness to the
surface even of an iron file.
This carbonaceous matter may be readily obtained from any of the soft
parts of animals, or from blood. For this purpose, however, the refuse
of shoemakers and curriers is the most convenient. After the volatile
parts have been distilled over, from an iron still, a bright shining
coal is left behind, which, when reduced to powder, is fit to mix with
the salt. Let about equal parts, by bulk, of this powder, and muriate of
soda be ground together, and brought to the consistence of cream, by the
addition of water. Or mix the powdered carbon with a saturated solution
of the salt, till it become of the above consistence. Files which are
intended to be very hard, should be covered with this composition,
previous to hardening. All files intended to file iron or steel,
particularly saw files, should be hardened with the aid of this mixture,
in preference to that with the flour or grounds. Indeed, it is probable,
that the carbonaceous powder might be used by itself, in point of
economy, since the ammonia or hartshorn, obtained by distillation, would
be of such value as to render the coal of no expense. By means of this
method the files made of iron, which, in itself, is unsusceptible of
hardening, acquire a superficial hardness sufficient for any file
whatever. Such files may, at the same time, be bent into any form; and,
in consequence, are particularly useful for sculptors and die-sinkers.
The next point to be considered is the best method of heating the file
for hardening. For this purpose a fire, similar to the common smiths’
fire, is generally employed. The file is held in a pair of tongs by the
tang, and introduced into the fire, consisting of very small cokes,
pushing it more or less into the fire for the purpose of heating it
regularly. It must frequently be withdrawn with the view of observing
that it is not too hot in any part. When it is uniformly heated, from
the tang to the point, of a cherry red colour, it is fit to quench in
the water. At present an oven, formed of fire-bricks, is used for the
larger files, into which the blast of the bellows is directed, being
open at one end, for the purpose of introducing the files and the fuel.
Near to the top of the oven are placed two cross bars, on which a few
files are placed, to be partially heating. In the hardening of heavy
files, this contrivance affords a considerable saving, in point of time,
while it permits them also to be more uniformly and thoroughly heated.
After the file is properly heated for the purpose of hardening, in order
to produce the greatest possible hardness, it should be cooled as soon
as possible. The most common method of effecting this is by quenching it
in the coldest water. Some file-makers have been in the habit of putting
different substances in their water, with a view to increase its
hardening property. The addition of sulphuric acid to the water was long
held a great secret in the hardening of saw files. After all, however,
it will be found, that clear spring water, free from animal and
vegetable matter, and as cold as possible, is the best calculated for
hardening files of every description.
In quenching the files in water, some caution must be observed. All
files, except the half-round, should be immersed perpendicularly, as
quickly as possible, so that the upper part shall not cool. This
management prevents the file from warping. The half-round file must be
quenched in the same steady manner; but, at the same time that it is
kept perpendicular to the surface of the water, it must be moved a
little horizontally, in the direction of the round side, otherwise it
will become crooked backwards.
After the files are hardened, they are brushed over with water, and
powdered cokes, when the surface becomes perfectly clean and metallic.
They ought also to be washed well in two or three clean waters, for the
purpose of carrying off all the salt, which, if allowed to remain, will
be liable to rust the file. They should moreover be dipped into
lime-water, and rapidly dried before the fire, after being oiled with
olive oil, containing a little oil of turpentine, while still warm. They
are then finished.
FILLIGREE (_Filigrane_, Fr.; _Filigran_, or _Feine Drahtgeflecht_,
Germ.); is, as the last term justly expresses it, intertwisted fine
wire, used for ornamenting gold and silver trinkets. The wire is seldom
drawn round, but generally flat or angular; and soldered by gold or
silver solder with borax and the blowpipe. The Italian word,
_filigrana_, is compounded of _filum_ and _granum_, or granular
net-work; because the Italians, who first introduced this style of work,
placed small beads upon it.
FILTRATION (Eng. and Fr.; _Filtriren_, Germ.), is a process purely
mechanical, for separating a liquid from the undissolved particles
floating in it, which liquid may be either the useful part, as in
vegetable infusions, or of no use, as the washings of mineral
precipitates. The filtering substance may consist of any porous matter
in a solid, foliated, or pulverulent form; as porous earthen ware,
unsized paper, cloth of many kinds, or sand. The white blotting paper
sold by the stationers answers extremely well for filters in chemical
experiments, provided it be previously washed with dilute muriatic acid,
to remove some lime and iron that are generally present in it. Filter
papers are first cut square, and then folded twice diagonally into the
shape of a cornet, having the angular parts rounded off. Or the piece of
paper being cut into a circle, may be folded fan-like from the centre,
with the folds placed exteriorly, and turned out sharp by the pressure
of the finger and thumb, to keep intervals between the paper and the
funnel into which it is fitted, to favour the percolation. The diameter
of the funnel should be about three-fourths of its height, measured from
the neck to the edge. If it be more divergent, the slope will be too
small for the ready efflux of the fluid. A filter covered with the
sediment is most conveniently washed by spouting water upon it with a
little syringe. A small camel’s-hair paint brush is much employed for
collecting and turning over the contents in their soft state. Agitation
or vibration is of singular efficacy in quickening percolation, as it
displaces the particles of the moistened powders, and opens up the pores
which had become closed. Instead of a funnel, a cylindrical vessel may
be employed, having its perforated bottom covered with a disc of
filtering powder folded up at the edges, and made tight there by a wire
ring. Linen or calico is used for weak alkaline liquors; and flannels,
twilled woollen cloth, or felt-stuff for weak acid ones. These filter
bags are often made conical like a fool’s cap, and have their mouths
supported by a wooden or metallic hoop. Cotton wool put loose into the
neck of a funnel answers well for filtering oils upon the small scale.
In the large way, oil is filtered in conical woollen bags, or in a cask
with many conical tubes in its bottom, filled with tow or cotton wool.
Stronger acid and alkaline liquors must be filtered through a layer of
pounded glass, quartz, clean sand, or bruised charcoal. The alcarrhazas
are a porous biscuit of stone ware made in Spain, which are convenient
for filtering water, as also the porous filtering stone of Teneriffe,
largely imported into England at one time, but now superseded in a great
measure by the artificial filters patented under many forms, consisting
essentially of strata of gravel, sand, and charcoal powder.
It is convenient to render the filter self-acting, by accommodating the
supply of liquid to the rate of percolation, so that the pressure upon
the porous surface may be always equally great. Upon the small scale,
the lamp-fountain or bird’s-glass form so generally used for lamps, will
be found to answer.
[Illustration: 386 387]
_Fig._ 386. represents a glass bottle A, partly filled with the fluid to
be filtered, supported in the ring of a chemical stand, and having its
mouth inverted into the same liquor in the filter funnel. It is obvious,
that whenever this liquor by filtration falls below the lip of the
bottle, air will enter into it, let down a fresh supply to feed the
filter, and keep the funnel regularly charged. If larger quantities are
to be operated upon, the following apparatus may be employed. _Fig._
387. A B is a metallic vessel which may be made air-tight; C is the
under pipe provided with a stopcock R, for letting down the liquor into
the filter _a b_. The upper pipe _t_, through which the fluid is poured
by means of the funnel E, has also a stopcock which opens or shuts, at
the same time, the small side tube _u t_, through which, during the
entrance of the fluid, the air is let off from the receiver. A glass
tube _g_, shows the level of the liquor in the body of the apparatus. In
using it, the cock R must be first closed, and the cock S must be opened
to fill the receiver. Then the filter is set a going, by re-opening the
cock R, so as to keep the fluid in the filter upon a level with the
opening of the tube C. Both these pieces of apparatus are essentially
the same.
[Illustration: 388 389]
In many manufactures, self-acting filters are fed by the plumber’s
common contrivance of a ball-cock in which the sinking and rising of the
ball, within certain limits, serves to open or shut off the supply of
liquor, as it may be required or not. Dumont has adopted this expedient
for his system of filtering syrup through a stratum of granularly ground
animal charcoal or bone-black. _Fig._ 388. is a front view of this
apparatus with 4 filters C; and _fig._ 389. is a cross section. The
framework B supports the cistern A, in which the syrup is contained.
From it the liquor flows through the stop-cock _b_, and the
connection-tube _a_, into the common pipe _c_, which communicates, by
the short branch tubes _e_, with each of the four filters. The end of
the branch tube, which is inside of the filter tub, is provided with a
stopcock _d f_, whose opening, and thereby the efflux of the liquor from
the cistern through the tube _a_, is regulated by means of the
float-ball _g_. Upon the brickwork D the filter tub stands, furnished at
_h_ with a false bottom of zinc or copper pierced with fine holes;
besides which, higher up at _i_ there is another such plate of metal
furnished with a strong handle _k_, by which it may be removed, when the
bone-black needs to be changed. In the intervening space _l_, the
granular coal is placed. _o_ is the cover of the filter tub, with a
handle also for lifting it. One portion of it may be raised by a hinge,
when it is desired to inspect the progress of the filtration within. _m
m_ is a slender vertical tube, forming a communication between the
bottom part _h_, and the upper portion of the filter, to admit of the
easy escape of the air from that space, and from among the bone-black as
the syrup descends; otherwise the filtration could not go on. _p_ is the
stopcock through which the fluid collected in the space under _h_ is let
off from time to time into the common pipe _q_, _fig._ 388. _r_ is a
trickling channel or groove lying parallel to the tube _q_, and in
which, by means of a tube _s_, inserted at pleasure, the syrup is drawn
off in case of its flowing in a turbid state, when it must be returned
over the surface of the charcoal.
The celerity with which any fluid passes through the filter depends, 1.
upon the porosity of the filtering substance; 2. upon the pressure
exercised upon it; and 3. upon the extent of the filtering surface. Fine
powders in a liquor somewhat glutinous, or closely compacted, admit of
much slower filtration than those which are coarse and free; and the
former ought, therefore, to be spread in a thinner stratum and over a
more extensive surface than the latter, for equal effect; a principle
well exemplified in the working of Dumont’s apparatus, just described.
[Illustration: 390]
In many cases filtration may be accelerated by the increase of
hydrostatic or pneumatic pressure. This happens when we close the top of
a filtering cylinder, and connect it by a pipe with a cistern of fluid
placed upon a higher level. The pressure of the air may be rendered
operative also either by withdrawing it partially from a close vessel,
into which the bottom of the filter enters, or by increasing its density
over the top of the liquor to be filtered. Either the air pump or steam
may be employed to create a partial void in the receiver beneath the
filter. In like manner, a forcing pump or steam may be employed to exert
pressure upon the surface of the filtering liquor. A common syphon may,
on the same principle, be made a good pressure filter, by making its
upper leg trumpet-shaped, covering the orifice with filter paper or
cloth, and filling the whole with liquor, the lower leg being of such
length so as to create considerable pressure by the difference of
hydrostatic level. This apparatus is very convenient either on the small
or great scale, for filtering off a clear fluid from a light muddy
sediment. The pressure of the atmosphere may be elegantly applied to
common filters, by the apparatus represented in _fig._ 390., which is
merely a funnel inclosed within a gasometer. The case A B bears an
annular hollow vessel _a b_, filled with water, in which receiver the
cylindrical gasometer _d_, _e_, _f_, _i_, is immersed. The filter funnel
C is secured at its upper edge to the inner surface of the annular
vessel _a b_. In consequence of the pressure of the gasometer regulated
by the weight _g_, upon the air inclosed within it, the liquid is
equally pressed, and the water in the annular space rises to a
corresponding height on the outer surface of the gasometer, as shown in
the figure. Were the apparatus made of sheet iron, the annular space
might be charged with mercury.
In general, relatively to the application of pressure to filters, it may
be remarked, that it cannot be pushed very far, without the chance of
deranging the apparatus, or rendering the filtered liquor muddy. The
enlargement of the surface is, generally speaking, the safest and most
efficacious plan of increasing the rapidity of filtration, especially
for liquids of a glutinous nature. This expedient is well illustrated in
the creased bag filter now in use in most of the sugar refineries of
London. See SUGAR.
In many cases it is convenient so to construct the filtering apparatus,
as that the liquid shall not descend, but mount by hydrostatic pressure.
This method has two advantages: 1. that without much expensive
apparatus, any desired degree of hydrostatic pressure may be given, as
also that the liquid may be forced up through several filtering surfaces
placed alongside of each other; 2. that the object of filtering, which
is to separate the particles floating in the fluid without disturbing
the sediment, may be perfectly attained, and thus very foul liquids be
cleared without greatly soiling the filtering surface.
[Illustration: 391]
Such a construction is peculiarly applicable to the purification of
water, either alone, or combined with the downwards plan of filtration.
Of the former variety an example is shown in _fig._ 391. The wooden or
zinc conical vessel is provided with two perforated bottoms or sieves _e
e_, betwixt which the filtering substance is packed. Over this, for the
formation of the space _h h_, there is a third shelf, with a hole in its
middle, through which the tube _d b_ is passed, so as to be water tight.
This places the upper open part of the apparatus in communication with
the lowest space _a_. From the compartment _h h_ a small air tube _l_
runs upwards. The filtering substance consists at bottom of pebbles, in
the middle of gravel, and at the top of fine sand, which may be mixed
with coarsely ground bone-black, or covered with a layer of the same.
The water to be filtered being poured into the cistern at top, fills
through the tube _b d_ the inferior compartment _a_, from which the
hydrostatic pressure forces the water upward through the perforated
shelf, and the filtering materials. The pure water collects in the space
_h h_, while the air escapes by the small tube _l_, as the liquid
enters. The stopcock _i_ serves to draw off the filtered water. As the
motion of the fluid in the filter is slow, the particles suspended in it
have time to subside by their own gravity; hence there collects over the
upper shelf at _d_, as well as over the under one at _a_, a precipitate
or deposit which may be washed out of the latter cavity by means of the
stopcock _m_.
[Illustration: 392]
As an example of an upwards and downwards filter, _fig._ 392. may be
exhibited. A B C D is a wooden or metallic cistern furnished with the
perforated shelf _c d_ near its under part, upon which a vertical
partition is fixed through the axis of the vessel. A semicircular
perforated shelf is placed at _a_, and a second similar one at _b_.
These horizontal shelves rest upon brackets in the sides of the
cisterns, so that they may be readily lifted out. The space G is filled
with coarse sand, J with moderately fine, and H with very fine. The foul
water is poured into the chamber E, and presses through G J H and into
the space F; whence it may be drawn by the stopcock _f_.
[Illustration: 393]
_Fig._ 393. represents in section a filtering apparatus consisting of
two concentric chambers; the interior being destined for downwards
filtration, and the exterior for upwards. Within the larger cistern A, a
smaller one B is placed concentrically, with its under part, and is left
open from distance to distance, to make a communication between the
interior cavity and the exterior annular space. These cavities are
filled to the marked height with sand and gravel. The inner cylindrical
space has fine sand below, then sharper sand with granular charcoal,
next coarse sand, and lastly gravel. The annular space has in like
manner fine sand below. The foul water is introduced by the pipe E, the
orifice at whose end is acted upon by a ball-cock with its lever _a_;
whereby the water is kept always at the same level in the inner vessel.
The water sinks through the sand strata of the middle vessel, passes
outwards at its bottom into the annular space, thence up through the
sand in it, and collecting above it, is let off by the stopcock on the
pipe _b_. When a muddy deposit forms after some time, it may be easily
cleared out. The cord _e_, running over the pulleys _f f_, being drawn
tight, the ball lever will shut up the valve. The stopcock _d_ made fast
to the conducting tube E must then be opened, so that the water now
overflows into the annular space at A; the tube _c_, in communication
with the inner space B, being opened by taking out the stopper _h_. The
water thereby percolates through the sand strata in the reverse
direction of its usual course, so as to clear away the impurities in the
space B, and to discharge them by the pipe _c h_. An apparatus of this
kind of moderate size is capable of filtering a great body of water. It
should be constructed for that purpose of masonry; but upon a small
scale it may be made of stone-ware.
[Illustration: 394]
A convenient apparatus for filtering oil upwards is represented in
_fig._ 394. _g_ is an oil cask, in which the impure parts of the oil
have accumulated over the bottom. Immediately above this, a pipe _a_ is
let in, which communicates with an elevated water cistern _n_. _f_ is
the filter, (placed on the lid of the cask) furnished with two
perforated shelves, one at _e_ and another at _d_; which divide the
interior of the filter into three compartments. Into the lower space
immediately over the shelf _e_, the tube _b_, furnished with a stopcock
enters, to establish a communication with the cask; the middle cavity
_e_ is filled with coarsely ground charcoal or other filtering
materials; and the upper one has an eduction pipe _l_. When the
stopcocks of the tubes _a_ and _b_ are opened, the water passes from the
cistern into the oil cask, occupies from its density always the lowest
place, and presses the oil upwards, without mixing the two liquids;
whereby first the upper and purer portion of the oil is forced through
tube _b_ into the filter, and thence out through the pipe _l_. When the
fouler oil follows, it deposits its impurities in the space under the
partition _c_, which may from time to time be drawn off through the
stopcock _k_, while the purer oil is pressed upwards through the filter.
In this way the different strata of oil in the cask may be filtered off
in succession, and kept separate, if found necessary for sale or use,
without running any risk of mixing up the muddy matter with what is
clear. According to the height of the water cistern _n_, will be the
pressure, and of course the filtering force. When the filter gets choked
with dirt, it may be easily re-charged with fresh materials.
In filtering caustic alkaline lyes through linen or quartz, it is proper
to exclude the free contact of air; which is done by inclosing the upper
vessel, and attaching a pipe of communication between its cover, and the
shoulder of the lower vessel, or recipient of the lyes. In proportion as
these flow down, they will displace their bulk of air, and drive it into
the top of the upper vessel above the foul lyes.
Many modifications of the above described apparatus are now on sale in
this country; but certainly the neatest, most economical, and effective
means of transforming the water of a stagnant muddy pool, into that of a
crystalline fountain, is afforded by the Royal Patent Filters of George
Robins.
FIRE ARMS, MANUFACTURE OF. This art is divided into two branches, that
of the metallic and of the wooden work. The first includes the barrel,
the lock, and the mounting, as also the bayonet and ramrod, with
military arms. The second comprises the stock, and in fowling pieces,
likewise the ramrod.
1. _The Barrel._ Its interior is called the bore; its diameter, the
calibre; the back end, the breech; the front end, the muzzle; and the
closing of the back end, the breech pin or plug. The barrel is generally
made of iron. Most military musquets and low-priced guns are fashioned
out of a long slip of sheet-iron folded together edge-wise round a
skewer into a cylinder, are then lapped over at the seam, and welded at
a white heat. The most ductile and tenacious soft iron, free from all
blemishes, must be selected for this slip. It is frequently welded at
the common forge, but a proper air-furnace answers better, not being so
apt to burn it. It should be covered with ashes or cinders. The shape of
the bore is given by hammering the cylinder upon a steel mandril, in a
groove of the anvil. Six inches of the barrel at either end are left
open for forming the breech and the muzzle by a subsequent welding
operation; the extremity put into the fire being stopped with clay, to
prevent the introduction of cinders. For every length of two inches,
there are from two to three welding operations, divided into alternating
high and low heats; the latter being intended to correct the defects of
the former. The breech and muzzle are not welded upon the mandril, but
upon the horn of the anvil; the breech being thicker in the metal, is
more highly heated, and is made somewhat wider to save labour to the
borer. The barrel is finally hammered in the groove of the anvil without
the mandril, during which process it receives a heat every two minutes.
In welding, the barrel extends about one-third in length; and for
musquets, is eventually left from 3 to 3-1/2 feet long; but for cavalry
pistols, only 9 inches.
The best iron plates for gun-barrels are those made of _stub_ iron, that
is of old horse-shoe nails welded together, and forged into thin bars,
or rather narrow ribands. At one time _damascus_ barrels were much in
vogue; they were fashioned either as above described, from plates made
of bars of iron and steel laid parallel, and welded together, or from
ribands of the same damascus stuff coiled into a cylinder at a red heat,
and then welded together at the seams. The best modern barrels for
fowling pieces are constructed of stub-nail iron in this manner. The
slip or fillet is only half an inch broad or sometimes less, and is left
thicker at the end which is to form the breech, and thinner at the end
which is to form the muzzle, than in the intermediate portion. This
fillet being moderately heated to increase its pliancy, is then lapped
round the mandril in a spiral direction till a proper length of cylinder
is formed; the edges being made to overlap a little in order to give
them a better hold in the welding process. The coil being taken off the
mandril and again heated, is struck down vertically with its muzzle end
upon the anvil, whereby the spiral junctions are made closer and more
uniform. It is now welded at several successive heats, hammered by
horizontal strokes, called _jumping_, and brought into proper shape on
the mandril. The finer barrels are made of still narrower, stub-iron
slips, whence they get the name of wire twist. On the Continent, barrels
are made of steel wire, welded together lengthwise, then coiled spirally
into a cylinder. Barrels that are to be rifled, require to be made of
thicker iron, and that of the very best quality, for they would be
spoiled by the least portion of scale upon their inside. Soldiers’
musquets are thickened a little at the muzzle, to give a stout holding
to the bayonet.
[Illustration: 395]
The barrels thus made are annealed with a gentle heat in a proper
furnace, and slowly cooled. They are now ready for the borer, which is
an oblong square _bit_ of steel, pressed in its rotation against the
barrel, by a slip of wood applied to one of its flat sides, and held in
its place by a ring of metal. The boring bench works horizontally, and
has a very shaky appearance, in respect at least of the bit. In some
cases, however, it has been attempted to work the barrels and bits at an
inclination to the horizon of 30°, in order to facilitate the discharge
of the borings. The barrel is held in a slot by only one point, to allow
it to humour the movements of the borer, which would otherwise be
infallibly broken. The bit, as represented in _fig._ 395., has merely
its square head inserted into a clamp-chuck of the lathe, and plays
freely through the rest of its length.
[Illustration: 396]
_Fig._ 396. represents in plan the _boring bench_ for musquet barrels;
_f f_ is the sledge or carriage frame in which the barrel is supported;
_a_ is the revolving chuck of the lathe, into which the square end of
the bit, _fig._. 395., is inserted; _b_ is the barrel, clamped at its
middle to the carriage, and capable of being pressed onwards against the
tapering bit of the borer, by the bent lever _c_, worked by the left
hand of the operative against fulcrum knobs at _d_, which stand about
two inches asunder. Whenever the barrel has been thereby advanced a
certain space to the right, the bent end of the lever is shifted against
another knob or pin. The borer appears to a stranger to be a very
awkward and unsteady mechanism, but its perpetual vibrations do not
affect the accuracy of the bore. The opening broach may be of a square
or pentagonal form; and either gradually tapered from its thickest part,
or of uniform diameter till within two inches of the end, whence it is
suddenly tapered to a point.
A series of bits may be used for boring a barrel, beginning with the
smallest and ending with the largest. But this multiplication of tools
becomes unnecessary, by laying against the cutting part of the bit,
slips of wood, called spales, of gradually increasing thickness, so that
the edge is pressed by them progressively further from the axis. The
bore is next polished. This is done by a bit with a very smooth edge,
which is mounted as above, with a wedge of wood besmeared with a mixture
of oil and emery. The inside is finished by working a cylindrical steel
file quickly backwards and forwards within it, while it is revolving
slowly.
In boring, the bit must be well oiled or greased, and the barrel must be
kept cool by letting water trickle on it; for the bit, revolving at the
rate of 120 or 140 times a minute, generates a great deal of heat. If a
flaw be detected in the barrel during the boring, that part is hammered
in, and then the bit is employed to turn it out.
Many sportsmen are of opinion that a barrel with a bore somewhat
narrowed towards the muzzle serves to keep shot better together; and
that roughening its inside with pounded glass has a good effect, with
the same view. For this purpose, also, fine spiral lines have been made
in their interior surface. The justness of its calibre is tried by means
of a truly turned cylinder of steel, 3 or 4 inches long, which ought to
move without friction, but with uniform contact from end to end of the
barrel. Whatever irregularities appear must be immediately removed.
The outer surface of the barrel is commonly polished upon a dry
grindstone, but it is better finished, and less dangerously to the
workman, at a turning lathe with a slide rest. If a stone be used, it
should be made to revolve at the mouth of a tunnel of some kind, into
which there is a good draught to carry off the ferruginous particles. A
piece of moist cloth or leather should be suspended before the orifice.
Rifle barrels have parallel grooves of a square or angular form cut
within them, each groove being drawn in succession. These grooves run
spirally, and form each an aliquot part of a revolution from the chamber
to the muzzle. Rifles should not be too deeply indented; only so much as
to prevent the ball turning round within the barrel. and the spires
should be truly parallel, that the ball may glide along with a regular
pace. See _infra_.
The Parisian gun-makers, who are reckoned very expert, draw out the iron
for the barrels at hand forges, in fillets only one-ninth of an inch
thick, one inch and a half broad, and four feet long. Twenty-five of
these ribands are laid upon each other, between two similar ones of
double thickness, and the bundle, weighing 60 pounds, bound with wire at
two places, serves to make two barrels. The thicker plates are intended
to protect the thinner from the violence of the fire in the numerous
successive heats necessary to complete the welding, and to form the
bundle into a bar two-thirds of an inch broad, by half an inch thick;
the direction of the individual plates relatively to the breadth being
preserved. This bar folded flat upon itself, is again wrought at the
forge, till it is only half an inch broad, and a quarter of an inch
thick, while the plates of the primitive ribands are now set
perpendicular to the breadth of the narrow fillet; the length of which
must be 15 or 16 feet French (16 or 17 English), to form a fowling piece
from 28 to 30 inches long. This fillet, heated to a cherry red in
successive portions, is coiled into as close a spiral as possible, upon
a mandril about two-fifths of an inch in diameter. The mandril has at
one end a stout head for drawing it out, by means of the hammer and the
grooves of the anvil, previous to every heating. The welding is
performed upon a mandril introduced after each heat; the middle of the
barrel being first worked, while the fillets are forced back against
each other, along the surface of the mandril, to secure their perfect
union. The original plates having in the formation of the ultimate long
riband become very thin, appear upon the surface of the barrel like
threads of a fine screw, with blackish tints to mark the junctions. In
making a double-barrelled gun, the two are formed from the same bundle
of slips, the coils of the one finished fillet being turned to the right
hand, and those of the other to the left.
The Damascus barrels forged as above described, from a bundle of steel
and iron plates laid alternately together, are twisted at the forge
several times, then coiled and welded as usual. Fifteen Parisian workmen
concur in one operation: six at the forge; two at the boring mill; seven
at filing, turning, and adjusting; yet all together make only six pairs
of barrels per week, which are sold at from 100 to 300 francs the pair,
ready for putting into the stock.
[Illustration: 397 398]
The breeching is of three kinds: the common; the chamber, plug, or
mortar, _fig._ 397.; and the patent, _fig._ 398. The common was formerly
used for soldiers’ musquets and inferior pieces. The second is a
trifling improvement upon it. In the patent breeching, the screws do not
interfere with the touch-hole, and the ignition is quicker in the main
chamber.
[Illustration: 399]
The only locks which it is worth while to describe are those upon the
percussion principle, as flint locks will certainly soon cease to be
employed even in military musquets. Forsyth’s lock (_fig._ 399.) was an
ingenious contrivance. It has a magazine _a_, for containing the
detonating powder, which revolves round a roller _b_, whose end is
screwed into the breech of the barrel. The priming powder passes through
a small hole in the roller, which leads to a channel in communication
with the chamber of the gun.
The pan for holding the priming is placed immediately over the little
hole in the roller. There is a steel punch _c_, in the magazine, whose
under end stands above the pan, ready to ignite the priming when struck
upon the top by the cock _d_, whenever the trigger is drawn. The punch
immediately after being driven down into the pan is raised by the action
of a spiral spring. For each explosion, the magazine must be turned so
far round as to let fall a portion of the percussion powder into the
pan; after which it is turned back, and the steel punch recovers its
proper position for striking another blow into the pan.
[Illustration: 400]
The invention of the copper percussion cap was another great improvement
upon the detonating plan. _Fig._ 400. represents the ordinary percussion
lock, which is happily divested of three awkward projections upon the
flint lock, namely, the hammer, hammer spring, and the pan. Nothing now
appears upon the plate of the lock, but the cock or striking hammer,
which inflicts the proper blow upon the percussion cap. It is concave,
with a small metallic ring or border, called a shield or fence, for the
purpose of enclosing the cap, as it were, and preventing its splinters
doing injury to the sportsman, as also protecting against the line of
flame which may issue from the touch-hole in the cap nipple. This is
screwed into the patent breech, and is perforated with a small hole.
[Illustration: 401]
The safety lock of Dr. Somerville is a truly humane invention. Its
essential feature is a slide stop or catch, placed under the trigger A,
_fig._ 401. It is pulled forward into a notch in the trigger, by means
of a spring B, upon the front of the guard, which is worked by a key C,
pressing upon the spring when the piece is discharged. In another safety
plan there is a small movable curved piece of iron, A, which rises
through an opening B, in the lock-plate C, and prevents the cock from
reaching the nipple, as represented in the figure, until it is drawn
back within the plate of the lock when the piece is fired.
To fire this gun, two different points must be pressed at the same time.
If by accident the key which works the safety be touched, nothing
happens, because the trigger is not drawn; and the trigger touched alone
can produce no effect, because it is locked. The pressure must be
applied to the trigger and the key at the same instant, otherwise the
lock will not work.
The French musquet is longer than the British, in the proportion of
44·72 inches to 42; but the French bayonet is 15 inches, whereas the
British is 17.
Eng. Fr.
Dimensions. Dimensions.
Diameter of the bore 0·75 in. 0·69 in.
Diameter of the ball 0·676 0·65
Weight of the ball in oz. 1·06 0·958
Weight of the firelock and bayonet in libs. 12·25 10·980
Length of the barrel and bayonet 59·00 59·72
[Illustration: 402]
Within these few years a great many contrivances have been brought
forward, and several have been patented for fire arms. The first I shall
notice is that of Charles Random, Baron de Berenger. _Fig._ 402. shows
the lock and breech of a fowling piece, with a sliding protector on one
of the improved plans; _a_ is the hammer, _b_ the nipple of the
touch-hole, _c_ a bent lever, turning upon a pin, fixed into the
lock-plate at _d_. The upper end of this bent lever stands partly under
the nose of the hammer, and while in that situation stops it from
striking the nipple. A slider _g f h_, connected with the under part of
the gun-stock, is attached to the tail of the bent lever at _i_; and
when the piece is brought to the shoulder for firing, the hand of the
sportsman pressing against the bent part of the slider at _g_, forces
this back, and thereby moves the end of the lever _c_ forwards from
under the nose of the cock or hammer, as shown by the dotted lines. The
trigger being now drawn, the piece will be discharged; and on removing
the hand from the end _g_, of the slider _f_, the spring at _h_ acting
against the guard, will force the slider forward, and the lever into the
position first described.
[Illustration: 403]
Mr. Redford, gun-maker of Birmingham, proposes a modification of the
lock for small fire-arms, in which the application of pressure to the
sear spring for discharging the piece is made by means of a plug,
depressed by the thumb, instead of the force of the finger exerted
against the trigger. _Fig._ 403. represents a fowling piece partly in
section. The sear spring is shown at _a_. It is not here connected with
the trigger as in other locks; but is attached by a double-jointed piece
to a lever _b_, which turns upon a fulcrum pin in its centre. At the
reverse end of this lever an arm extends forwards, like that of an
ordinary sear spring, upon which arm the lower end of the plug _c_ is
intended to bear; and when this plug is depressed by the thumb bearing
upon it, that end of the lever _b_ will be forced downwards, and the
reverse end will be raised, so as to draw up the end of the sear spring,
and set off the piece. For the sake of protection, the head of the plug
_c_ is covered by a movable cap _d_, forming part of a slider _e_, which
moves to and fro in a groove in the stock, behind the breech end of the
barrel; this slider _e_ is acted upon by the trigger through levers,
which might be attached to the other side of the lock-plate; but are not
shown in this figure to avoid confusion. When the piece is brought to
the shoulder for firing, the fore-finger must be applied as usual to the
trigger, but merely for the purpose of drawing back the slider _e_, and
uncovering the head of the plug; when this is done, the thumb is to be
pressed upon the head of the plug, and will thus discharge the piece. A
spring bearing against the lever of the slider _e_, will, when the
finger is withdrawn from the trigger, send the slider forward again, and
cover the head of the plug, as shown.
It is with pleasure I again advert to the humane ingenuity of the Rev.
John Somerville, of Currie. In April, 1835, he obtained a patent for a
further invention to prevent the accidental discharge of fire arms. It
consists in hindering the hammer from reaching the nipple of a
percussion lock, or the flint reaching the steel of an ordinary one, by
the interposition of movable safety studs or pins, which protrude from
under the false breech before the hammers of the locks, and prevent them
from descending to strike. These safety studs or pins are moved out of
the way by the pressure of the right hand of the person using the gun
only when in the act of firing, that is, when the force of the right
hand and arm is exerted to press the butt end of the stock of the gun
against the shoulder while the aim is taken and the trigger pulled. In
carrying the gun at rest, the proper parts of the thumb or hand do not
come over Mr. Somerville’s movable buttons or studs.
[Illustration: 404 405]
_Fig._ 404. is a side view of part of a double percussion gun; and
_fig._ 405. is a top or plan view, which will serve to explain these
improvements, and show one, out of many, methods of carrying them into
effect. A is the stock of the gun; B the barrels; C the breech; D the
nipples; E the false breech, on the under side of which the levers which
work the safety studs or pins are placed; F is the shield of the false
breech; G, triggers; H the lock-plate; and I the hammers: all of which
are constructed as usual: _a a_ are the safety studs or pins, which
protrude before the shield F, and work through guide pieces on the under
side of the false breech. The button piece is placed in the position for
the thumb of the right hand to act upon it; but when the pressure of the
ball of the right thumb is to produce the movement of the safety studs,
it must be placed in or near the position K; and when the heel of the
right hand is to effect the movements of the safety studs, the button
piece must be placed at L, or nearly so.
In these last two positions, the lever (which is acted upon by the
button piece to work the safety studs through a slide) would require to
be of a different shape and differently mounted. When the hammers are
down upon the nipples after discharging the gun, the ends of the safety
pins press against the inner sides of the hammers. When this invention
is adapted to single-barrelled guns, only one pin, _a_, one lever and
button piece will be required.
[Illustration: 406]
Mr. Richards, gun-maker, Birmingham, patented, in March, 1836, a
modification of the copper cap for holding the percussion powder, as
represented _fig._ 406.; in which the powder is removed from the top of
the cap, and brought nearer the mouth; _a_ being the top, _b_ the sides,
and _c_ the position of the priming. The dotted lines show the direction
of the explosion, whereby it is seen that the metal case is opened or
distended only in a small degree, and not likely to burst to pieces, as
in the common caps, the space between _a_ and _c_ being occupied by a
piece of any kind of hard metal _d_, soldered or otherwise fastened in
the cap.
George Lovell, Esq., director of the Royal Manufactory of Arms at
Enfield, has recently made a great improvement upon the priming chamber.
He forms it into a vertical double cone, joined in the middle by the
common apex; the base of the upper cone being in contact with the
percussion cap, presents the most extensive surface to the fulminate
upon the one hand, while the base of the under one being in a line with
the interior surface of the barrel, presents the largest surface to the
gunpowder charge, upon the other. In the old nipple the apex of the cone
being at its top, afforded very injudiciously the _minimum_ surface to
the exploding force.
_Guns, Rifling of the Barrels._--The outside of rifle barrels is, in
general, octagonal. After the barrel is bored, and rendered truly
cylindrical, it is fixed upon the rifling machine. This instrument is
formed upon a square plank of wood 7 feet long, to which is fitted a
tube about an inch in diameter, with spiral grooves deeply cut
internally through its whole length; and to this a circular plate is
attached, about 5 inches diameter, accurately divided in concentric
circles, into from 5 to 16 equal parts, and supported by two rings made
fast to the plank, in which rings it revolves. An arm connected with the
dividing graduated plate, and pierced with holes, through which a pin
is passed, regulates the change of the tube in giving the desired number
of grooves to the barrel. An iron rod, with a movable handle at the one
end, and a steel cutter in the other, passes through the above rifling
tube. This rod is covered with a core of lead one foot long. The barrel
is firmly fixed by two rings on the plank, standing in a straight line
on the tube. The rod is now drawn repeatedly through the barrel, from
end to end, until the cutter has formed one groove of the proper depth.
The pin is then shifted to another hole in the dividing plate, and the
operation of grooving is repeated till the whole number of riflings is
completed. The barrel is next taken out of the machine, and finished.
This is done by casting upon the end of a small iron rod a core of lead,
which, when besmeared with a mixture of fine emery and oil, is drawn,
for a considerable time, by the workmen, from the one end of the barrel
to the other, till the inner surface has become finely polished. The
best degree of spirality is found to be from a quarter to half a
revolution in a length of three feet.
_Military Rifles._--An essential improvement in this destructive arm has
lately been introduced into the British service, at the suggestion of
Mr. Lovell:
[Illustration: 407 408 409 410]
The intention in all rifles is to impart to the ball a rotatory or
spinning motion round its axis, as it passes out through the barrel.
This object was attained, to a certain degree, in the rifles of the old
pattern, by cutting seven spiral grooves into the inside of the barrel,
in the manner shewn by _fig._ 407., the spherical ball, _fig._ 408.,
being a little larger than the bore, was driven down with a mallet, by
which the projecting ribs were forced into the surface of the ball, so
as to keep it in contact with their curvatures, during its expulsion.
Instead of this laborious and insecure process, the barrel being now cut
with only two opposite grooves, _fig._ 409., and the ball being formed
with a projecting belt, or zone, round its equator, of the same form as
the two grooves, _fig._ 410., it enters so readily into these hollows,
that little or no force is required to press it down upon the powder. So
much more hold of the barrel is at the same time obtained, that instead
of one _quarter_ of a turn, which was the utmost that could be safely
given in the old way, without danger of stripping the ball, a _whole_
turn round the barrel, in its length, can be given to the two grooved
rifles; whereby a far more certain and complete rotatory motion is
imparted to the ball. The grand practical result is, that better
practice has been performed by several companies of the Rifle Corps, at
300 yards, than could be produced with the best old military rifles at
150 yards; the soldier being meanwhile enabled to load with much greater
ease and despatch. The belt is bevelled to its middle line, and not so
flat as shown in the figure.
This mode of rifling is not, however, new in England. In fact, it is one
of the oldest upon record; and appears to have fallen into disuse from
faults in the execution. The idea was revived within the last few years
in Brunswick, and it was tried in Hanover also, but with a lens-shaped
(Linsenförmig) ball. The judicious modifications and improvements it has
finally received in Mr. Lovell’s hands, have brought out all its
advantages, and rendered it, when skilfully used, a weapon of unerring
aim, even at the prodigious distance of 700 yards.
[Illustration: 411
_Mr. Lovell’s Lock._]
The locks, also, for the military service generally, are now receiving
an important improvement by means of his labours, having been simplified
in a remarkable manner. The action of the main spring is reversed, as
shown by _fig._ 411.; thus rendering the whole mechanism more solid,
compact, and convenient; while the ignition of the charge being effected
by percussion powders in a copper cap, the fire of the British line
will, in future, be more murderous than ever, as a mis-fire is hardly
ever experienced with the fire-arms made at the Royal manufactory, under
Mr. Lovell’s skilful superintendence.
FIRE-DAMP; the explosive carburetted hydrogen of coal mines. See
PITCOAL.
FIRE-WORKS. (_Feux d’artifice_, Fr.; _Feuerwerke_, Germ.) The
composition of luminous devices with explosive combustibles, is a modern
art resulting from the discovery of gunpowder. The finest inventions of
this kind are due to the celebrated Ruggieri, father and son, who
executed in Rome and Paris, and the principal capitals of Europe, the
most brilliant and beautiful fireworks that were ever seen. The
following description of their processes will probably prove interesting
to many of my readers.
The three prime materials of this art are, nitre, sulphur, and charcoal,
along with filings of iron, steel, copper, zinc, and resin, camphor,
lycopodium, &c. Gunpowder is used either in grain, half crushed, or
finely ground, for different purposes. The longer the iron filings, the
brighter red and white sparks they give; those being preferred which are
made with a very coarse file, and quite free from rust. Steel filings
and cast-iron borings contain carbon, and afford a more brilliant fire,
with wavy radiations. Copper filings give a greenish tint to flame;
those of zinc, a fine blue colour; the sulphuret of antimony gives a
less greenish blue than zinc, but with much smoke; amber affords a
yellow fire, as well as colophony, and common salt; but the last must be
very dry. Lampblack produces a very red colour with gunpowder, and a
pink with nitre in excess. It serves for making golden showers. The
yellow sand or glistening mica, communicates to fire-works golden
radiations. Verdigris imparts a pale green; sulphate of copper and
sal-ammoniac, a palm-tree green. Camphor yields a very white flame and
aromatic fumes, which mask the bad smell of other substances. Benzoin
and storax are used also on account of their agreeable odour. Lycopodium
burns with a rose colour and a magnificent flame; but it is principally
employed in theatres to represent lightning, or to charge the torch of a
fury.
Fire-works are divided into three classes: 1. those to be set off upon
the ground; 2. those which are shot up into the air; and 3. those which
act upon or under water.
Composition for _jets of fire_; the common preparation for rockets not
more than 3/4 of an inch in diameter, is: gunpowder, 16 parts; charcoal,
3 parts. For those of larger diameter: gunpowder, 16; steel filings, 4.
_Brilliant revolving wheel_; for a tube less than 3/4 of an inch:
gunpowder, 16; steel filings, 3. When more than 3/4: gunpowder, 16;
filings, 4.
_Chinese or Jasmine fire_; when less than 3/4 of an inch: gunpowder, 16;
nitre, 8; charcoal (fine), 3; sulphur, 3; pounded cast-iron borings
(small), 10. When wider than 3/4: gunpowder, 16; nitre, 12; charcoal, 3;
sulphur, 3; coarse borings, 12.
_A fixed brilliant_; less than 3/4 in diameter: gunpowder, 16; steel
filings, 4; or, gunpowder, 16; and finely pounded borings, 6.
_Fixed suns_ are composed of a certain number of jets of fire
distributed circularly, like the spokes of a wheel. All the fusees take
fire at once through channels charged with quick matches. _Glories_ are
large suns with several rows of fusees. _Fans_ are portions of a sun,
being sectors of a circle. The _Patte d’oie_ is a fan with only three
jets.
The _mosaic_ represents a surface covered with diamond shaped
compartments, formed by two series of parallel lines crossing each
other. This effect is produced by placing at each point of intersection,
four jets of fire, which run into the adjoining ones. The intervals
between the jets must be associated with the discharge of others, so as
to keep up a succession of fires in the spaces.
_Palm trees._ Ruggieri contrived a new kind of fire, adapted to
represent all sorts of trees, and especially the palm. The following is
the composition of this magnificent green fire-work: crystallized
verdigris, 4 parts; sulphate of copper, 2; sal-ammoniac, 1. These
ingredients are to be ground and moistened with alcohol. An artificial
tree of any kind being erected, coarse cotton rovings about 2 inches in
diameter, impregnated with that composition, are to be festooned round
the trunk, branches, and among the leaves; and immediately kindled
before the spirits have had time to evaporate.
_Cascades_, imitate sheets or jets of water. The Chinese fire is best
adapted to such decorations.
_Fixed stars._ The bottom of a rocket is to be stuffed with clay, and
one diameter in height of the first preparation being introduced, the
vacant space is to be filled with the following composition, and the
mouth tied up. The pasteboard must be pierced into the preparation, with
five holes, for the escape of the luminous rays, which represent a
star.
_Composition of fixed stars_:--
Ordinary. Brighter. Coloured.
Nitre, 16 12 0
Sulphur, 4 6 6
Gunpowder meal, 4 12 16
Antimony, 2 1 2
_Lances_, are long rockets of small diameter, made with cartridge paper.
Those which burn quickest should be the longest. They are charged by
hand without any mould, with rods of different lengths, and are not
strangled at the mouth, but merely stuffed with a quick match of tow.
These lances form the figures of great decorations; they are fixed with
sprigs upon large wooden frame works, representing temples, palaces,
pagodas, &c. The whole are placed in communication by _conduits_, or
small paper cartridges like the lances, but somewhat conical, that they
may fit endwise into one another to any extent that may be desired. Each
is furnished with a match thread fully 1-1/2 inches long, at its two
ends.
Composition for the _white lances_: nitre, 16; sulphur, 8; gunpowder, 4
or 3. For a _bluish-white_: nitre, 16; sulphur, 8; antimony, 4. For
_blue lances_: nitre, 16; antimony, 8. For _yellow_: nitre, 16;
gunpowder, 16; sulphur, 8; amber, 8. For _yellower_ ones: nitre, 16;
gunpowder, 16; sulphur, 4; colophony, 3; amber, 4. For _greenish_ ones:
nitre, 16; sulphur, 6; antimony, 6; verdigris, 6. For _pink lances_;
nitre, 16; gunpowder, 3; lampblack, 1. Others less vivid are made with:
nitre, 16; colophony, 3; amber, 3; lycopodium, 3.
Cordage is represented in fire-works, by imbuing soft ropes with a
mixture of, nitre, 2; sulphur, 16; antimony, 1; resin of juniper, 1.
The Bengal flames rival the light of day. They consist of, nitre, 7;
sulphur, 2; antimony, 1. This mixture is pressed strongly into earthen
porringers, with some bits of quick match strewed over the surface.
These flames have a fine theatrical effect for conflagrations.
_Revolving suns_, are wheels upon whose circumference rockets of
different styles are fixed, and which communicate by _conduits_, so that
one is lighted up in succession after another. The composition of their
common fire is, for sizes below 3/4 of an inch: gunpowder meal, 16;
charcoal, not too fine, 3. For larger sizes: gunpowder, 20; charcoal,
not too fine, 4. For _fiery radiations_: gunpowder, 16; yellow micaceous
sand, 2 or 3. For _mixed radiations_: gunpowder, 16; pitcoal, 1; yellow
sand, 1 or 2.
The _waving or double Catherine wheels_, are two suns turning about the
same axis in opposite directions. The fusees are fixed obliquely and not
tangentially to their peripheries. The wheel spokes are charged with a
great number of fusees; two of the four wings revolve in the one
direction, and the other two in the opposite; but always in a vertical
plane.
The _girandoles_, _caprices_, _spirals_, and some others have on the
contrary a horizontal rotation. The fire-worker may diversify their
effects greatly by the arrangement and colour of the jets of flame. Let
us take for an example the _globe of light_. Imagine a large sphere
turning freely upon its axis, along with a hollow hemisphere, which
revolves also upon a vertical axis passing through its under pole. If
the two pieces be covered with coloured lances or cordage, a fixed
luminous globe will be formed, but if horizontal fusees be added upon
the hemisphere, and vertical fusees upon the sphere, the first will have
a relative horizontal movement, the second a vertical movement, which
being combined with the first, will cause it to describe a species of
curve, whose effect will be an agreeable contrast with the regular
movement of the hemisphere. Upon the surface of a revolving sun, smaller
suns might be placed, to revolve like satellites round their primaries.
Ruggieri exhibited a luminous serpent pursuing with a rapid winding
pace, a butterfly which flew continually before it. This extraordinary
effect was produced in the following way. Upon the summits of an octagon
he fixed eight equal wheels turning freely upon their axles, in the
vertical plane of the octagon. An endless chain passed round their
circumference, going from the interior to the exterior, covering the
outside semi-circumference of the first, the inside of the second, and
so in succession; whence arose the appearance of a great festooned
circular line. The chain, like that of a watch, carried upon a portion
of its length a sort of scales pierced with holes for receiving coloured
lances, in order to represent a fiery serpent. At a little distance
there was a butterfly constructed with white lances. The piece was
kindled commonly by other fireworks, which seemed to end their play, by
projecting the serpent from the bosom of the flames. The motion was
communicated to the chain by one of the wheels, which received it like a
clock from the action of a weight. This remarkably curious mechanism was
called by the artists a _salamander_.
_The rockets which rise into the air_ with a prodigious velocity, are
among the most common, but not least interesting fire-works. When
employed profusely they form those rich volleys of fire which are the
crowning ornaments of a public fête. The cartridge is similar to that of
the other jets, except in regard to its length, and the necessity of
pasting it strongly, and planing it well; but it is charged in a
different manner. As the sky-rockets must fly off with rapidity, their
composition should be such as to kindle instantly throughout their
length, and extricate a vast volume of elastic fluids. To effect this
purpose, a small cylindric space is left vacant round the axis; that is,
the central line is tubular. The fire-workers call this space the soul
of the rocket (_ame de la fusée_). On account of its somewhat conical
form, hollow rods, adjustable to different sizes of broaches or skewers,
are required in packing the charge; which must be done while the
cartridge is sustained by its outside mould, or copper cylinder. The
composition of sky-rockets is as follows:--
+-------------------------+----------+---------+------+
| When the bore is |3/4 of an | 3/4 to |1-2/3;|
| | inch; | 1-1/4; | |
+-------------------------+----------+---------+------+
|Nitre |16 |16 | 16 |
|Charcoal | 7 | 8 | 9 |
|Sulphur | 4 | 4 | 4 |
| _Brilliant Fire._ | | | |
|Nitre |16 |16 | 16 |
|Charcoal | 6 | 7 | 8 |
|Sulphur | 4 | 4 | 4 |
|Fine steel filings | 3 | 4 | 5 |
| _Chinese Fire._ | | | |
|Nitre |16 |16 | 16 |
|Charcoal | 4 | 5 | 6 |
|Sulphur | 3 | 3 | 4 |
|Fine borings of cast iron| 3 coarser| 4 mixed | 5 |
+-------------------------+----------+---------+------+
The cartridge being charged as above described, the _pot_ must be
adjusted to it, with the _garniture_; that is, the serpents, the
crackers, the stars, the showers of fire, &c. The pot is a tube of
pasteboard wider than the body of the rocket, and about one third of its
length. After being strangled at the bottom like the mouth of a phial,
it is attached to the end of the fusee by means of twine and paste.
These are afterwards covered with paper. The garniture is introduced by
the neck, and a paper plug is laid over it. The whole is inclosed within
a tube of pasteboard terminating in a cone, which is firmly pasted to
the pot. The quick-match is now finally inserted into the _soul_ of the
rocket. The rod attached to the end of the sky-rockets to direct their
flight, is made of willow or any other light wood. M. Ruggieri replaced
the rod by conical wings containing explosive materials, and thereby
made them fly further and straighter.