vertical sun, may be exhibited in the following manner: Let a pyramid
be made twenty-one feet in height, and the height of the pedestal
six feet, and breadth nine feet, having a space between the rails of
six inches. They must be made as thin as possible, and in all put
port-fires at intervals of four inches. The Archimedean screws are
placed on the pedestal. They are nothing more than double spiral
wheels, on which the cases are placed, but horizontally instead of
obliquely. The vertical sun, placed four feet below the top of the
pyramid, may consist of twelve rays. The globe on the top may be
made in proportion to the pyramid. The leaders must be prepared and
arranged in such a manner, that all the illuminating port-fires, or
lances, screws, globe, and sun may take fire together.
Transparent stars with illuminated rays are formed, by making a
strong circular block or body for the star, two feet in diameter,
and attaching to it illuminated rays. In the centre of the front of
the body, fix a spindle, on which put a double triangular wheel, six
inches in diameter, clothed with two-ounce cases of brilliant charge.
The cases on this wheel must burn only one at a time.
Round the edge of the body, nail a hoop made of thin wood or tin,
which must project in front six or seven inches. In this hoop, cut
three or four holes to let out the smoke from the wheel. The star may
be cut out of strong pasteboard or tin in the following manner: Cut
a round piece of pasteboard, two feet in diameter, on which draw a
star, and cut it out. Over the vacancy, paste Persian silk, and paint
the letters yellow; and also four of the rays yellow, and four red.
This transparent star is to be fixed to the wooden hoop by a screw,
to take off and on. The illuminated rays are made of thin wood,
with tin sockets, fixed on their sides, within four inches of each
other. In these rockets, put the illuminating port-fires, or lances;
and behind the point of each ray, attach a half pound case of gray,
black, or Chinese fire. The illuminated rays are to be lighted at the
same time as the triangular wheel, or after it is burnt out. This may
be done by a tin barrel, in the manner described in the regulated
piece. Into this barrel, carry a leader from the illuminated rays,
through the back of the star, which must be met by another leader,
brought from the tail of the last case on the wheel.
The regulated illuminated spiral piece, with a projected star wheel,
also illuminated, is made by procuring a block, eight inches in
diameter, and putting in six iron spokes, which serve for spindles
for the spiral wheels. These wheels are made one and a half feet
in diameter, and three feet in height. The spindles must be of
sufficient length to keep the wheels four or five inches from one
another. At the end of each spindle, put a screw nut. On these
spindles, the wheels, that hang downwards, are to run. On the
spindles, which stand upwards, must be a shoulder, for the blocks
of the wheels to run on. The projected star wheel turns on the same
spindle on which the large block is fixed. This spindle must be long
enough to admit the star-wheel to project a little before the spiral
wheels. The exterior diameter of the star wheel is five feet five
inches. On this wheel, three circles of iron wire are to be fixed, to
which attach either port, or other illuminating fires. On the block,
place a transparent star, or a large five-pointed brilliant star. The
cases on this wheel may burn four at once. The cases on the spiral
wheels must be placed parallel to their fells and burn two at a time.
In order to make a figure-piece, with five-pointed stars,
illuminated, all that is necessary is to have a vertical wheel about
one foot in diameter, and furnished with six four-ounce cases of
different coloured charge, which must burn double. On the frame of
the figure piece, fix five-pointed brilliant or blue stars, rammed
four inches with composition. Let the space between each star be
eight inches, and, at each point, fix a gerbe or case of Chinese
fire. The gerbe, stars, and wheel are to be lighted at the same time.
The illuminated star wheel may be formed by procuring a fell about
four feet in diameter, and placing, within this fell, three circles
of iron wire, one smaller than the other, so that the diameter of
the least may be about ten inches. Place the port, or other fires on
these fells, with their mouths inclining outwards, and the port-fires
on the points of the star, with their mouths projecting in front. The
exterior fell must be clothed with four-ounce cases of gray charge.
They must burn four at a time and be lighted at the same time with
the illuminations.
The illuminated regulating piece as it is called, consists of flat
wooden spokes, each five feet long, and at the end of each, a
vertical wheel, ten inches diameter, and clothed with six four-ounce
cases of brilliant fire. These cases burn one at a time. On two of
the spokes of each wheel, two port-fires are attached, which must be
lighted with the first case of the wheel. On each spoke, behind the
wheels, place six cases of the same size with those on the wheels.
These cases must be tied across the spokes with their mouths in one
direction, and be made to take fire in succession.
The diameter of the large wheel must be two and a half feet, and
its fell made of wood, which is to be fixed to the large spokes.
Twenty-four cases of the same kind are fixed on this wheel, and burn
four at a time. On the circles of iron-wire, already mentioned,
illuminating port-fires are attached. The star-points on the large
spokes may be made of thin ash-hoops. The diameter of these points,
close to the centre wheel, is usually eleven inches. On these,
port-fires are placed, three and a half inches distant from each
other.
The illuminated double cone-wheel is nothing more than a double cone,
formed of a number of hoops, and supported by three or four pieces
of wood, in the manner of the spiral wheels. The wheel to which the
cones are attached, base to base, is two feet six inches in diameter,
and the height of each cone is three feet six inches. Port-fires, or
lances, are tied to each of the hoops, in a horizontal direction,
with their mouths outwards. The cases are eight-ounce, and play
horizontally, two at a time. The spindle for this piece must rise
three feet above the point of the cone at top; so that its length
will be ten feet four inches from the top of the post, in which it
is fixed, allowing four inches for the thickness of the block of the
wheel. The whole weight of the wheel and cones must be made to bear
on a shoulder in the spindle, on which the block of the wheel is
to turn. On the top of the spindle, fix a sun, composed of sixteen
four-ounce cases of brilliant fire. These cases must be stuck into
a block, six inches in diameter. In the front of this sun, put a
circular vertical wheel, sixteen inches in diameter. On the front of
this wheel, form a spiral with wire, to which attach illuminations
in the usual manner. This wheel is to be fired, when the cones are
burnt out, which may be done as before described. The sun must not be
fired, until the vertical wheel is burnt out. Three vertical wheels
illuminated, which turn on their own naves upon a horizontal table,
is a piece readily formed. It consists in having a table, three feet
in diameter fixed horizontally on the top of a post, with three
wheels that turn round on it. There are three spokes, joined to a
triangular flat piece of wood, in the middle of which, a hole is made
to fit easily over a spindle placed in the centre of the table. There
are three pieces of wood four or five inches long, and two inches
square, fixed on the under sides of the spokes. In these pieces,
holes are made lengthwise, to receive the thin parts of the blocks
of the wheels, which, when in, are prevented from coming out by a
small iron pin that runs through the end of each. The three vertical
octagon wheels, each eighteen inches in diameter, have blocks
sufficiently long, for three or four inches to rest on the table.
Round these a number of sharp points of wire are driven, (which must
not project out of the blocks more than 1/16th of an inch), and the
clothing is affixed in the usual manner. The use of the points is
this, that, when the blocks turn round, they will stick in the table
and assist in giving a uniform motion to the wheel. On the front of
the wheels, make four or five circles of strong wire, or flat hoops,
and tie, on these circles, as many illuminations, as they will hold,
at two inches from each other. Spiral lines may be made instead of
circles. When illuminations are fixed in a spiral line, in the front
of a wheel, they ought to be placed on the slant. The cases for these
wheels may be filled with any coloured charge, but must burn only one
at a time. A globe, or spiral wheel may be put on the spindle, so
that its fire may play over the vertical wheels. The wheels must be
lighted at the same time, and the illuminations, after two cases of
each wheel are consumed.
The vertical scroll wheel is formed by taking a block of a moderate
size, and fixing in it four flat spokes, and, on them, a flat
circular fell of wood. Round the front of this fell, port-fires are
placed; and on the front of the spokes a scroll is formed either with
a hoop or strong iron-wire. On this scroll, tie cases of brilliant
fire in proportion to the wheel, head to tail. When the first case
near the fell is lighted, the fire is communicated in succession.
The grand volute, with a projected wheel in front, is made in the
following manner: Two hoops are formed of strong iron wire, one
of six feet in diameter, and the other of four feet two inches.
These hoops must be joined to scrolls, formed according to fancy,
of the same kind of wire. On these, tie, with iron wire, as many
illuminating port-fires, as they will carry, at two inches distance.
Prepare then a circular wheel of four spokes, three feet six inches
in diameter, and, on its fell, tie as many four-ounce cases, head
to tail, as will complete the circle, only allowing a sufficient
distance between the cases, that the fire may pass free. On each
spoke, fix a four-ounce case, about three inches from the fell of
the wheel. These cases are to burn one at a time, and the first of
them to begin with those on the fell, of which four are to burn at a
time. On the front of the wheel, form a spiral line with strong wire,
on which tie port-fires, with their mouths to face the same way as
the cases on the wheel. All these port-fires must be fired with the
second cases on the wheel.
The spokes of the wheel must be formed of wood, and made to screw
into a block in the centre, and each spoke should be four feet six
inches in length. In the top of each, fix a spindle, and, in each
spindle, put a spiral wheel of eight spokes. The blocks of these
wheels must have a hole at top for the centre cases, and the spindle
must be furnished with nuts, screwed on their ends, which should fit
in the holes at the top of the blocks. The cases of these wheels
are to burn double; and the method of firing them, is by carrying a
leader from each down the spokes into the block in the centre, as in
the dodecaedron; but the centre cases of each wheel must begin with
the two last cases as usual. The large circular wheel in front ought
to have a tin barrel on its block; into which a pipe must be carried
from one of the second cases on the wheel. This pipe, being met by
another from the large block, in which the eight spokes are screwed,
will fire all the spiral wheels, and the illuminating port-fires at
the same time. The cases of the projected wheel may be filled with a
white charge, and those of the spiral wheels with a gray.
_Sec. XXI. Of the Spiral or Endless Screw, and Waved Fire._
This piece is formed in the same manner as the single and double
cones; and, in fact, is the same as the Archimedean screw, which we
have already described. The serpentine form which characterizes the
spiral piece, is given to it by the particular arrangement of the
lances of illumination. The cone receives its motion from the cases
of white-fire; the fire of which is communicated by leaders to the
cases of port-fire, or lances of illumination. They must burn the
same length of time.
The waved fire is produced by having two wheels of a similar size,
turning in a contrary direction on the same axis, and furnished with
cases, which are inclined about 45 degrees from the level of the
table. These wheels carry four cases each, and burn at the same time.
They have been made to carry forty-eight cases, and furnished, at
their centres, with lances, bent in a particular manner, so as to
represent the motion of serpents.
_Sec. XXII. Of the Decoration of Wheels._
Wheels, we have seen, may be made of different dimensions, according
to the purpose to which they are applied. The most common are three
or four feet in diameter, with a nave of hard wood, and spokes of
light wood. They are sometimes surmounted with a fell, and frequently
by several concentric hoops, placed at different distances from each
other.
Wheels, in general, are furnished with cases, and various
decorations. Some have two, three, four, and more fires; but, if they
are _finished_ too much, the weight they thus acquire would retard
the velocity of the wheel. Their centres may be finished in several
ways; as, for instance, by attaching, to the inner fells or circles,
cases filled with white lance-composition, placed at the distance of
two inches from each other, or alternately, white, blue, and yellow,
or Chinese gerbes, or cases of blue fire. We may also attach small
turning suns, the axes of which being placed upon the spokes. They
may also be made to resemble a mirror, by furnishing all the spokes
with white lances; and for the last fire, we may attach four cases to
the centre, or in its vicinity, placed in such a manner, that their
fire may issue from the interior of the wheel. To this, we may add,
two other cases, which may cross the former. Leaders are fixed, and
they are lighted at the same time.
Automatons with all their joints, or articulations, have been added
to exhibitions of this kind, and with particular effect. They are
clothed with cases after the usual manner.
_Sec. XXIII. Of Globes, with their Various Decorations._
The first we purpose to treat of are the illuminated globes with
horizontal wheels.
The hoops for these globes may be made of wood, tin, or iron wire,
about two feet in diameter. For a single globe, take two hoops and
tie them together, one within the other, at right angles; then have
a horizontal wheel made, whose diameter must be a little wider than
the globe, and its nave six inches long; on the top of which, the
globe is fixed so as to stand three or four inches from the wheel.
On this wheel may be put any number of cases, filled with any of the
ordinary charges, as the white fire composition. Two of these cases
must burn at a time. They may be placed horizontally, or inclining
downwards. When the wheel is clothed, fix on the hoops as many
illuminations as will stand, within two and a half inches of each
other, which are fastened on the hoops with small iron wire. Attach
the pipes of communication, and arrange them so as to carry the fire
to all at the same time, with the exception of one or two, which are
to receive their fire for the last. The spindle, on which the globe
is to turn, must go through the block of the wheel up to the inside
of the top of the globe; at this place must be fixed a bit of brass
or iron, with a hole in it, to receive the point of the spindle, on
which the whole weight of the wheel is to bear. When the globe is to
be stationary and the wheel to run by itself, the block of the wheel
must not be so long, or the spindle any longer than to raise the
globe a little above the wheel.
We may remark, that, while the cases of white fire composition give
to the piece a rotary motion, those of the lance or illuminating
port-fire produce the effect, which characterizes in particular this
fire-work.
With respect to fire globes, there are two kinds; namely, one with
projected cases, and the other with concealed cases. If we have a
globe made of wood, of any diameter, and divide its surface into
twenty-four equal parts, and bore a perpendicular hole in each of
these divisions to the centre, we may then represent this piece in
the following manner: In every hole, except one, put a case filled
with brilliant or any other charge, and let the mouths of the cases
be even with the surface of the globe. Then cut in the globe a groove
from the mouth of one case to that of another for leaders, which must
be carried from case to case, so that they may all be fired together.
The globe is then covered with a single paper and painted.
Fire globes with projected cases are made in the following way:
Prepare a globe with fourteen holes, and fix in every hole except
one, a case, and let each case project from the globe two-thirds
of its length. Then clothe all the cases with leaders. It must be
supported by a spindle made to fit the hole in which there is no case.
The _bursting-globe_ is nothing more than a globe prepared in a
particular way. It turns on a pivot, and is made by uniting four
segments. These segments or parts are fixed to hinges, which open on
the inside, and, when brought together, are kept in their place by a
match which goes round the globe. The globe, it is to be observed, is
furnished in the inside with several steel springs, which, unless the
globe itself were tied, would force it open. When the match is burnt,
this effect follows and the globe separates into four parts. It is
furnished with lances and cases in the same manner as those already
described. The last effect is that we have noticed.
_Globes, which leap or roll on the ground_, may be formed by
procuring a wooden globe, furnished with a cylinder; and, having
loaded it with the composition hereafter mentioned, introduce into
it four or more petards loaded with grain powder to their orifices,
which must be well stopped with paper or tow. If a globe prepared
in this manner be fired by means of a match at the mouth of the
cylinder, it will leap about as it burns on a smooth horizontal
plane, according as the petards are set on fire. The petards may be
affixed to the exterior surface of the globes, which they will cause
to roll and leap as they catch fire.
_Composition._
Grained powder, 1 lb.
Saltpetre, 32 --
Sulphur, 8 --
Scraped ivory, 1 oz.
Sawdust, (boiled in saltpetre and dried,) 8 lbs.
_Sec. XXIV. Of the Representation of the Moon and Stars._
The moon and stars are represented in the following manner: Make a
wheel eighteen inches in diameter, by fixing eight or more spokes
in the nave; and then adapt a fell to it. To the fell fasten eight
cases of the black or gray composition, and let the fire communicate
from one to the other. These cases give motion to the wheel. Furnish
the spokes of this wheel with cases charged with the white lance
composition. Make now a crescent of iron and attach it to the spokes,
or a little before the spokes of the wheel. In order to fix stars
to this piece, eight strips of wood, seven feet in length, are made
to cross each other at equal distances, and nailed to each other in
the middle; so that when this frame is put behind and secured to the
moon-piece, its arms will extend some distance beyond the perimeter
of the wheel. These projections are furnished with five-pointed
stars, eight inches apart, and there is usually in all thirty-two.
They are made to communicate with each other by means of the cotton
match, as before described. The light of the lances renders the moon
very apparent, and the fixed stars resemble those in the firmament.
The representation of the moon and seven stars may be performed by
procuring a smooth, circular board, six feet in diameter. Out of
the middle of it cut a circular piece twelve or fourteen inches in
diameter, and cover the hole formed with Persian silk, on which is
to be painted a moon's face. Also cut out of the board stars of four
or five inches in diameter. These stars are cut out with five points
and covered with oiled silk. On the front of the large circular
board draw a seven-pointed star, as large as the circle will admit,
and on the lines which form this star, make several perforations, in
which six-pointed stars are to be fixed. A wheel of brilliant fire is
placed behind the moon, which renders the moon and stars transparent.
They will disappear when the wheel is burnt out; but then in
consequence of the communication of the fire to the large star in
front, which is formed of pointed stars, the appearance of this star
succeeds, and finishes the piece.
A large fixed star may be made thus. To each extremity of the pieces
of wood, arranged so as to cross each other, attach two cases of the
black charge. Their fire must communicate. Near these cases, on each
arm, place a turning sun of three cases. These five suns are fixed at
the same time, and when they cease, the cases commence. These cases
form the star.
The representation of flaming stars, with brilliant wheels, is
made in the following manner. After procuring a circular piece of
wood, about one inch thick, and two feet in diameter, fix round it
eight points, each two feet and a half long, four of which must be
straight and four waved, or flaming. These points being joined on
very strong, and even with the surface of the wood, nail tin or
pasteboard on their edges, from the wood to the end of each, where
they must be joined. This tin is to project in front eight inches,
and be joined where they meet at the block. Round the front of the
wood, fix four pieces of thick iron wire, eight inches long each,
equally distant from each other. Cut a piece of pasteboard round,
two feet in diameter, and draw on it a star; then cut out this star,
and on the back of it, place oiled paper. Paint half red and half
yellow, lengthwise. The body of the star must be left open in which
must be seen a brilliant wheel. This wheel is formed by having a
block turned nine inches long, and fixing in it six spokes. At the
end of each spoke, put a two-ounce case of brilliant fire. The length
of these cases is made in proportion to the wheel, and the diameter
of the wheel, when the cases are on, must be less than the diameter
of the body of the small star. The cases on the spokes in front must
have their mouths inclined outwards, and those on the inside spokes,
placed so as to form a vertical circle of fire.
Carry the first leader, from the tail of one of the cases in front,
to the mouth of one of the inside cases, and from the tail of that
to another in front, and in the same order to all of them. Put on a
spindle in the centre of the star. This spindle must be furnished
with a shoulder at bottom, to keep the wheel at a little distance
from the block, which is kept on the spindle by a nut at the end.
Having fixed on the wheel, fasten the transparent star to four pieces
of wire. When fired, a common horizontal wheel will only be seen; but
when the first case is burnt out, it will fire one of the vertical
cases, which will show the transparent star and fill the large flames
and points with fire. It will then appear like a common wheel, and
represent the same appearance for twelve changes.
With respect to the formation of stars for regulated pieces, we may
remark, that they are made of different sizes according to the work
for which they are intended. They are prepared with cases from one
ounce to one pound; but, in general, with four-ounce cases, four or
five inches long. The cases should be rolled with paste, and twice
as thick of paper as a rocket of the same caliber. Having rolled a
case, let one end of it be pinched quite close; then drive in half
a diameter of clay, and, when dry, fill it with composition to two
or three inches of the length of the case. At the top of the charge,
drive some clay; as the ends of these cases, being seldom pinched,
would be likely to take fire. Divide the case, when filled, at the
pinched end close to the clay, into five equal parts; then bore
five holes with a gimblet, about the size of the neck of a common
four-ounce case, into the composition. From one hole to another,
carry a quick match, and secure it with paper, in the same manner as
the ends of wheel cases; so that the hollow part, which projects from
the end of the case, may serve to receive a leader from any other
work, to give fire to the points of the stars. These stars may be
made with any number of points.
_Sec. XXV. Of the Representation of Sundry Figures in Fire._
Animals and various figures may be represented in fire by the
following method: Take sulphur, reduced to a very fine powder, and,
having formed it into a paste with starch, cover the figure of the
thing to be represented, with this mixture, having first coated it
with clay to prevent it from being burnt. After the figure is covered
with paste, it must be sprinkled, while moist, with gunpowder; and,
when the whole is perfectly dry, arrange about it several small
matches, that the fire may be speedily communicated to it on all
sides. In this way, all sorts of garlands, festoons, and other
ornaments may be imitated by fire of different colours.
A shower of fire may be connected with this representation, by using
cases of one-third of an inch in diameter, charged with any of the
following compositions. These cases should be two inches and a half
in length. They must not be choaked, it being sufficient to twist
the end of the cartridge. The effect of these cases is to fill the
surrounding air with an undulating fire. The compositions are similar
to those already noticed; viz. for _Chinese Fire_, take gunpowder
one pound, sulphur two ounces, pulverized cast-iron of No. 1. five
ounces; for _ancient fire_, meal-powder one pound, charcoal two
ounces; and for _brilliant fire_, meal-powder one pound, and iron
filings four ounces. Sparks are also sometimes employed. These are
made in the usual manner.
Besides the common mode of forming sparks, as they differ from stars
only in their size and duration, (being formed into small balls about
the size of peas), they may be made by the following method: Take
sawdust of fir, poplar, &c. and boil it in water, in which saltpetre
has been dissolved. When the water has boiled some time, it is to be
poured off, that the sawdust may remain in the vessel. When nearly
dry, spread it out on a table, and sprinkle it with sulphur, sifted
through a very fine sieve, to which may be added a little meal-powder.
If it be required to accompany the exhibition with bearded rockets,
(_fusées chevelues_ of the French), so called from the circumstance,
that, when they fall, they make small undulations in the air like
frizzled hair, we may form them in the following manner: Fill the
barrels of some goose-quills with the composition of sky-rockets,
and place upon the mouth of each a little moist gunpowder, both to
keep in the composition, and to serve as a match. If a flying-rocket
be then loaded with these quills, they will produce, at the end, a
beautiful shower of fire.
_Sec. XXVI. Of the Representation of Flat Stars, with a large Body of
Fire._
A star of five points, about two feet from point to point, is to be
made, and, in its centre, is placed a turning sun, composed of three
cases, and altogether not more than six or eight inches in diameter.
To this star five branches are fixed, each of which is three feet in
length; and, to the extremity of each, are attached seven cases, with
their mouths outwards, and inclining about thirty-five degrees. One
case is then attached lengthwise, and forms the very extremity of
each projection. On each leg or branch, nearer, however, the centre
of the star, must be three cases, fixed in an hexangular form. The
border of the large star is decorated with Italian or fixed stars.
The fire is communicated to the star by means of a leader, then to
the sun and the cases on the branches.
_Sec. XXVII. Of the Single, Double, and Triple Table Wheel._
We have spoken of an arrangement of fire-works, which moves a wheel
on a circular board. That contrivance is similar to the one we now
purpose to describe.
The table-wheel is a kind of girandole, which turns circularly on a
round table, by having its axis connected with a perpendicular pin,
fixed in the table; so that its motion is vertical, while it moves in
a circular position round the table.
The table, as well as the wheel, may be of any size, according to
fancy. Eight or nine cases are usually attached to the fell of the
wheel, and in the direction of the fell. These cases turn it with
great velocity. The centre of the wheel may be decorated with lances,
or illuminating port-fires. When double or treble wheels are to
be arranged on the same table, this is done by having the iron so
lengthened, as to extend over the table, and receive another wheel
of the same size; and by using a contrivance of iron, having three
projections, at equal distances apart, and turning in the same manner
on a pivot, or pin, fixed in the centre of the table, three wheels
may be put in motion at the same time. When two wheels are employed,
we may decorate one with blue lances, and the other with yellow.
When three wheels form the same piece, it is usual to illuminate
them, severally, with white, blue, and yellow lances. The wheels of
coloured fire augment the beauty of the exhibition. In the centre of
the table, may be placed a pyramid, decorated in the usual manner.
Spiral wheels, globes, &c. may be attached, if so required.
_Sec. XXVIII. Of Decorations, Transparencies, and Illuminations._
Cut-work, as it is called, is often employed in decorations. Various
figures, letters, garlands, &c. may be represented. This may also
be accomplished in tambour-work. Several methods have been used
to produce the same effect. Cut-work, made in pasteboard, and the
pasteboard blackened and suspended in a frame, will, by the aid of
lights placed behind it, exhibit the design very perfectly. A figure
of a sun cut out of pasteboard, either fixed or made to revolve in
the manner before described, and illuminated by fixed lights or
revolving cases, is considered to be the best mode of forming such
pieces. In all instances, the more brilliant the fire, the more
perfect is the representation. Tambour decorations are variously
arranged; and, frequently, in the termination of an exhibition, six
or more are shown at once, and sometimes with cascades, and turning
suns.
In the place of cut-work, painted transparencies, made with fine
colours, and on Florence Taffeta, are usually employed. Transparent
paintings however, are not preferred by some, as the effect, it is
said, is not so perfect as when cut-work is employed. Morel gives a
preference to the latter.
Transparencies may be formed with silk, or fine linen, and even with
paper, if previously prepared, by means of the spirit of turpentine.
The colours are painted in turpentine, and transparent varnish is
then applied.
Transparent screens may be prepared, by spreading white wax,
dissolved in spirits of turpentine, over thin muslin. A screen,
thus prepared, will roll up without injury. A clearer screen may be
produced, by having the muslin stretched upon a rectangular frame,
and prepared with turpentine instead of wax.
In the _Œuvres de Diderot_, t. xv, p. 349, are observations
respecting transparencies, and the manner of preparing them. The
process described is nothing more than we have noticed. It consists
in using the oil of turpentine, and sometimes a solution of wax
in turpentine. The colours are prepared mostly with turpentine.
Canada balsam, thinned by the addition of the spirit, is also
employed. Moveable transparencies were exhibited with great effect
in Paris. Transparent figures were made to move continually in every
direction, which had a singular appearance. Artificial fire-works
were very accurately imitated, by producing a variety of movements
with different pieces of transparencies, variously coloured. The
sun, moon, and stars, revolving wheels, &c. composed a part of this
exhibition.
With respect to decorations in white and coloured lances, we may
observe, that artificial fire-works are usually terminated by some
decoration, which corresponds with the subject. For this purpose,
triumphal arches, fronts of palaces, colonades, rocks, &c. are
formed, and represented in wood-work. These are usually clothed, and
painted in water-colours. From the rocks, water is made to issue,
forming cascades, and a number of figures are put in motion. The
jets of water are terminated by jets of Chinese fire, or brilliant
fire-rain.
The furniture, or decorations, may be various, either with white or
coloured lances of illumination, hung four inches apart, and attached
to different parts of the figure, or building. If it is in front of
a temple, the columns are ornamented with emblems, &c. the fire-work
being thus arranged: _viz._ blue lances are attached to the columns,
white lances to their entablature, and to the emblems, yellow lights.
This however, depends on taste.
Decorations are also made with matches; but this mode is not
preferred, because so much smoke is thereby produced.
Figures, cut in paper, are illuminated in the manner before
described. But for this purpose, muslin is first stretched on a
frame, and its sides are covered with two or three thicknesses of
paper, which are pasted on. It is then blackened. After tracing the
design, or the subject of the illumination, and cutting it out with
exactness, the frame is put in a case, sufficiently deep to contain a
number of lights.
Illuminations, as an expression, of public feeling for some event or
memorable occasion, are by no means a recent thing. Various modes
have been adopted to render such exhibitions more elegant, as well as
more expressive. Hence, with the usual display of lights, arranged
according to taste and fancy, transparencies, decorations, such as we
have described, &c. have been more or less customary.
We mentioned, in the first part of our work, something in relation
to the antiquity of illuminations; but, as this subject may be
interesting, we deem the following brief remarks not irrelevant.
Beckman assures us, (_History of Inventions_), that the origin
of illuminations is very ancient. The feasts, or holy-days were
celebrated in the days of antiquity, in various ways, among which,
that with lamps was very common in Egypt. It was called the feast
of the lamps, (_Fête des Lampes_), and the inhabitants of some
cities in Egypt were obliged to illuminate, with a great number of
lamps, placed before their houses. Herodotus (_lib._ ii, _chap._
62), remarks, that, at a particular festival of the Egyptians, lamps
were placed before all the houses throughout the country, and kept
burning the whole night. During the _festum encæniorum_, the Feast
of the Dedication of the Temple, which, according to common opinion,
was celebrated in December, and continued eight days, a number of
lamps were lighted before each of their houses. Such illuminations
were used, also, in Greece and Rome, and were called _Lampadaria_.
An infinite number of lamps were burnt in honour of Minerva, Vulcan,
Prometheus, Bacchus, &c. On the last occasion, the illumination was
called _Lamptericæ_. It seems that the lighting of streets had not
been adopted at that period.[25] At Rome, the forum was lighted,
when games were exhibited in the night-time; and Caligula, on a
like occasion, caused the whole city to be lighted. As Cicero was
returning home late at night, after Cataline's conspiracy had been
defeated, lamps and torches were lighted in all the streets, in
honour of that great orator. The emperor Constantine caused the
whole city of Constantinople to be illuminated with lamps and wax
candles on Easter-eve. The first christians often illuminated their
houses on idolatrous festivals, in a more elegant manner than the
heathens. This was dictated by policy. The houses of the ancients
were illuminated on birth-days, by suspending lamps from chains.
For illuminations at the present day, tallow is chiefly used. It is
clarified, for the making of candles, by means of alum. M. Olaine
in 1710 presented to the academy of sciences an apparatus for the
manufacture of candles. The _bougie economique_ of the French is
described in the _Journal de Paris_ for 1782. The outline of the
process for preparing them is as follows: Take eight parts of suet,
and melt it with one quart of water; and after straining it, and
returning it to the same boiler, add the same quantity of water, in
which was dissolved half an ounce of saltpetre, as much sal ammoniac,
and one ounce of alum. The boiling is continued to evaporate the
water. The wick is made of cotton or flax, and rolled in a solution
of camphor in petroleum, and afterwards covered in the usual manner
with the above composition.
In using tallow generally, quicklime is recommended to be added to
it in fusion. When the quicklime subsides, it is poured off. Another
mode recommended is to melt the tallow with vinegar, and to add to
it a decoction of rosemary, sage, laurel, and a small quantity of
turmeric; the whole being boiled until the water is evaporated. This
communicates, it is said, an agreeable odour, and a yellow colour.
Different modes of preparing tallow for candles have been used.
See _sal ammoniac_. With respect to ancient lamps, some account of
them has been published in the _Antiquities_, by Montfaucon and by
Passeri; and the _Journal des Savants_ 1682 and 1685 mentions the two
lamps of Boyle and Sturmius, and some account of the celebrated lamp
of Callimacus in the temple of Minerva. On the formation of lamps,
and the purification of oil, sundry patents have been granted both
in France and England. The argand lamp for burning its own smoke,
which it effects by a glass cylinder placed over the flame, is one
of the best improvements of the kind. The principle of these lamps
is the same, although variously modified in shape and structure. For
chemical purposes, an iron cylinder is substituted for glass. A lamp,
for the burning of tar and turpentine, with steam, has lately been
invented by Mr. Morey, (_see Silliman's Journal Vol. II._) Mr. E.
Clarke obtained a patent for a lamp calculated to burn tallow; the
principle of which is, that by the heat of the flame, the caloric
is conducted to the tallow by means of a piece of iron, which is
heated by it, and the tallow melts as it is wanted. This lamp may be
economically used, when common lamp oil is scarce and high in price.
A lamp is described in the _Repository of Arts_, to burn tallow.
As a wick, besides cotton, several substances have been recommended.
The filaments of amianthus, for instance, while they perform the
office of a wick, are incombustible. The _Journal de Verdun_ for
1748, announced incombustible wick by sieur Lespar. Touch wood, the
_tussilago sarfara_, and the _verbascum tapsus_ of Linnæus, are
also recommended. In 1783, Leger announced, in the _Journal de la
Blancherie_, that he had invented a match which would burn without
smoke and odour.
Lamps have been furnished with fixed and moveable mirrors, to throw
the light forward by reflection. The reverberatory lamps, revolving
lights for light houses, &c. are of this kind. Many patents have been
obtained for such contrivances, which we have not room to notice.
The inflammable air lamp for the table, described in the
_Dictionnaire de l'Industrie_, is nothing more than a spirit of
wine lamp, and used in lieu of hot bricks, or vessels filled with
boiling water for the warming of dishes, &c. In 1780, M. Ehrman, in
his _Description et usage de quelques lampes à air inflammable_,
describes a chafing dish with inflammable air, invented by Nevet,
which operates by the combustion of hydrogen gas.[26]
Fixed illuminations are more brilliant and more magnificent; as
the lights are more numerous, as well as more diversified. Wax,
spermaceti, or tallow candles, or oil burnt in tin lamps, or in glass
cups suspended by wire, are all used for the purpose. If the wick be
dipped in spirit of turpentine, it will take fire instantaneously. It
is unnecessary to make any remarks as to the arrangement of lights.
Large dishes containing melted tallow, and a wick proportionally
thick and suspended by means of a simple contrivance of tin, are
recommended for the same purpose. Coloured lights afford a variety.
The appearance of coloured flame may be produced by burning the oil
in coloured glasses, so disposed as to let the light pass through
the glass, or by placing lamps behind bottles filled with coloured
water.[27]
The coloured glasses which are sold in Paris for the purpose, are
formed with facets on the outside, which not only produce the
appearance of coloured flame, but also, according to the number of
facets, the refraction and reflection of the light. Arches, pyramids,
obelisks, &c. are lighted up in this manner.
The Pont Neuf, and the Seine in 1739, were illuminated at the
time of the splendid exhibition of fire-works. It is unnecessary,
however, to particularize on this head. We all remember the splendid
illuminations in all our cities during the late war, which were
indeed a true expression of our national and individual feeling.
Illuminations, in this country, before that time were very rare; none
we think since the peace of 1783, and the union under the federal
compact.
Phosphuret of lime, of the size of peas, thrown into water, will
afford, at short intervals, a brilliant flame of fire; for the
phosphuretted hydrogen gas thus produced has the property of
inflaming spontaneously in atmospheric air. Alcohol, containing
sundry salts in solution, will give a flame of various colours,
according to the salt it holds in solution. See _Alcohol_.
Illuminated works are much admired by the Italians, and particularly
the _Illuminated chandelier_, which is considered a great addition
to a collection of works. An illuminated chandelier is formed of
thin wood with arms extending on each side. Holes are bored in the
front of the branches and in the body, and also in the eagle (if it
be added,) at top, and distant from each other about three inches.
In these holes, we put illuminations, filled with white, blue and
brilliant charge. Having fixed in the port-fires, they must be
clothed with leaders, so that the chandelier and eagle may light
together.
We may also observe, that, for the speedy lighting of a number of
lamps, at one and the same time, quick-match enclosed in paper tubes
has been used. This quick-match is sometimes made to communicate
its fire to a sulphur match, prepared by dipping strands of cotton
in melted sulphur, and from this to the lamp. Several methods are
recommended for this purpose; one of which consists in dipping
cotton wick in the oil of spike, and arranging it along the wicks
of the different lamps, so that when inflamed the fire may pass
rapidly from one lamp to another. In 1772, M. Renault, a Parisian,
announced in the public papers, that he possessed a secret, by which
he could light 2000 lamps in five minutes, by means of a match of
communication.
We have some experiments and observations on coloured flame, by
Mr. Morey, in his essay on heat and light, in the second volume of
Silliman's _Journal of Science and Arts_, p. 120. The experiments are
curious, and worthy of remark. If water, he observes, be put into
one cylinder, and made to boil, and the steam be led to the bottom
of another included cylinder, containing spirits of turpentine, the
steam, when let out under a moderate pressure, carries off with
it a sufficient quantity of the spirit to burn with a pleasant
_white_ flame, free from smoke; but if the pressure be increased,
the flame will become in part or wholly blue. "Here," he adds, "as
in many other experiments, I have noticed, that different coloured
flames may be produced from the same materials--are the products
of combustion different?" He further observes, that "if the steam
of water, containing a small proportion of the vapour of rosin, be
driven against iron, at or below a red heat, it burns with a pleasant
_blue_ flame, which will be extended some way back into the column
of the vapour, intermixed with innumerable sparks of very white
flame, evidently particles of the rosin. If the vapours, when the
proportion of the rosin is very small, are made to pass between two
plates of iron, at or near a red heat, they can be inflamed on the
opposite sides of the plates, and will then, sometimes, burn with
an entirely _blue_ flame, although the vapour can not be inflamed,
without the intervention of the plates." He states other experiments,
made with tallow and steam, producing a _blue_ flame. The _blue_
colour seems to be owing to the pressure made use of; for, in his
second communication, (page 122, of the same volume), he mentions
white flame being produced by the vapour of water; and when it is in
a sufficient quantity, there is _no smoke_. If too great, combustion
ceases. Speaking of the colour of the flame, produced by mixed
vapours, (of the combustible and water), such as blue, blue and
white, white and intense white, he adds, that they may be imitated,
at pleasure, with the patent lamp stove, by burning tar, pitch pine,
or mineral coal and water. Newly made charcoal will take up about
three times its weight of water. "Sand, ashes, or fine clay," he
observes, "answers well for mixing with the tar, &c. If the latter
be made into a paste with equal parts of spirit of turpentine and
water, and cold lumps of it, of a conical form, be placed on a table,
and a flame applied, the vapours burn without smoke for a short
time, &c. If enclosed in a tin cylinder, and the vapour be made to
issue through small holes at the top, placed as before stated, or on
a plate over a chafing dish of coals, it burns with a very bright
light, free from smoke. If the cylinder be tight at the top and
the vapour be led from the inside at the top, down and through the
bottom, and there be made to issue in an oblique direction, and from
a number of small openings, it will burn with a beautiful flame and
supports and regulates, very accurately, its own evaporation. The
oblique direction carries the heat, in part, beyond the cylinder,
when the evaporation is too great.
"Every effect may be produced in consuming the smoke, and giving
an intense white flame, by using a certain proportion of water,
intimately blended or mixed with these vapours, that can be from an
access of oxygen furnished, by creating a very strong current of
air, with a high flue." The description of Morey's lamp stove, may
be seen in the same work. The steam, he observes, may be furnished
by a small tin boiler, and directed to or near the bottom of the
tar. An _intense white flame free from smoke_, may be thus produced
from tar, rosin, rough turpentine or the spirit, alcohol, oil,
fat, tallow, mineral coal, pitch pine wood, and the knots, birch
bark, and pumpkin, sun-flower, flax, and other seeds. With regard
to pine wood, he adds, it is the easiest managed, evaporates at a
lower temperature, consumes a greater proportion of water in its
combustion, contains the water within itself, and gives a brighter
light than common candles or lamps, and without smoke. The more
volatile parts are evaporated at a temperature below that of boiling
water, and burn well with three parts of the vapour of water;
the flame then, however, is nearly _blue_. Observations on the
application of this mode of producing light and heat, may be seen
in Silliman, p. 131, &c. It appears, that Gay-Lussac (_Annales de
Chimie_, for June, 1819,) has commented on Mr. Morey's plan.
Professor Hare (_Silliman's Journal_, vol. 2d, p. 172) also observes,
that the flame of hydrogen gas is rendered luminous, like that of
oil, by adding a small quantity of oil of turpentine to the usual
mixture for generating this gas; and that the addition of 1/17 of
the same fluid to alcohol, will give it the property of burning
with a highly luminous flame; and there is a certain point in the
proportions, at which the mixture burns without smoke, like a gas
light. In the first instance, he observes, when the ingredients are
at the proper temperature, the light is greater than that produced by
carburetted hydrogen gas. Speaking of this application of spirits,
the professor judiciously adds: "It might be serviceable to _morals_,
if the value of this article could be enhanced by _a new_ mode of
consumption." We find, also, that the effect of vapour on flame has
been noticed by Dr. Dana, in the same Journal, vol. 1, p. 40; by
which it appears, that when a jet of steam is made to pass into a
charcoal fire, the vividness of the combustion is increased, and
also the low attenuated flame of the coal; that it prevents the
smoke of a common oil lamp, and makes the flame brighter; that the
flame of spirit of turpentine, which is usually dull and reddish, is
rendered bright, and no smoke is formed; or when the vapour of both
are made to issue together from the same orifice, and inflamed, no
smoke appears; that a jet of steam, thrown into the flame of a spirit
of wine lamp, or into flames which evolve no smoke or carbonaceous
matter, produces the same effect as a current of air; but that, in
all flames which evolve smoke, steam produces an increased brightness
and a more perfect combustion. Dr. Dana further suggests, that steam
might be introduced into the flames of street lamps, which might be
so contrived as to keep water boiling, to produce the steam, and
thereby cause a more perfect combustion, and a greater quantity of
light from the same materials.
Count Rumford has shown, that the quantity of light, emitted by a
given portion of inflammable matter in combustion, is proportional,
in some high ratio, to the elevation of temperature; and that a lamp,
having many wicks near each other, so as mutually to increase their
heat, burns with infinitely more brilliancy than the Argand lamps in
common use. To measure the proportional intensities of two or more
lights; place them a few inches asunder, and at the distance of a
few feet or yards from a screen of white paper, or a white wall. On
holding a small card near the wall two shadows will be projected on
it, the darker one by the interception of the brighter light, and the
lighter shadow, by the interception of the duller light. Bring the
fainter light nearer to the card, or remove the brighter one further
from it, till both shadows acquire the same intensity. Measure now
the distances of the two lights, from the wall or screen, square
them, and you have the ratio of illumination. Thus, if an Argand
flame and a candle, stand at the distances of 10 feet and 4 feet,
respectively, when their shadows are equally deep, we have 10^2 and
4^2, or 100 and 16, or 6-1/4 and 1, for their relative quantities of
light.
The author of the _Dictionnaire de l'Industrie_, vol. iii, p. 365,
in treating on the subject of illumination, mentions different modes
of illuminating, both with and without transparencies. We know that
various mixtures will produce different coloured flame. Thus, arsenic
will burn with a beautiful white flame in oxygen gas; iron and steel
will burn also, affording a brilliant light; phosphorus and charcoal
with a white, and sulphur with a beautiful blue flame; zinc with a
green colour, &c.
Again, we know that a mixture of nitrate of strontia and charcoal
will burn with a rose coloured flame; one part of boracic acid, and
three of charcoal, with a green flame; one of nitrate of barytes, and
four of charcoal, with a yellow flame; and equal parts of nitrate of
lime and charcoal powder, with an orange flame. We also know, that
cotton dipt in oil of turpentine, or ardent spirit, rosin, camphor,
&c. will burn extremely vivid and beautiful.
The author, whom we have just quoted, gives some remarks on the
various coloured flames, that may interest the reader.
_Felt_ (_Feutre_, Fr.) he remarks, if put in the fire, will give
most beautiful colours, a golden yellow and a brilliant blue. And
this, he adds, may be proved by throwing pieces of old hats into the
fire; for these colours depend on the substances used in dying the
hat. He further remarks, that green oak wood gives a yellow flame,
and alcohol with sedative salt, (boracic acid), a blue, and that, by
uniting the flame of both, the product, as to colour, will be a green.
The flame of alcohol is changed of various colours, according to the
salt it holds in solution. Of this circumstance, Schatt was apprised,
when he gave some formula many years ago, on the manner of forming
coloured flame. Reaumur remarked also, the different colours which
some metals assume, when submitted to the action of heat, which is
known now to be the effect of oxidizement.
As respects the phenomena with felt, we are told, that, if we throw
into the fire the cuttings of hats, we will perceive at first a
white flame, and then in succession a blue, green, and violet colour;
all which, our author observes, proceeds from the verdigris and other
substances, employed in the composition of the dye stuff. There is
one fact, which he has asserted, which may probably be explained on
the _materiality_ of light, so far as regards the _formation_ of
colour, (not considering, however, the theory of Bancroft, given in
his _Philosophy of Permanent Colours_, or the more philosophical one
of Dr. Samuel Conover, of Philadelphia, in the Transactions of the
_American Philosophical Society_), and this fact is, that the flame
carries the colour to the object which it illuminates, and that the
object itself actually partakes of the colour, in order to produce
any particular appearance. That colours, as visible to the eye, are
all formed in the solar light, and their appearance depends upon the
_absorption_ of some of the rays of light, and the _reflection_ of
others, is a doctrine which followed the discoveries of Sir Isaac
Newton. We have not room to notice this subject, however interesting
it may be in a philosophical point of view.
There can be no doubt, that the art of colouring flame was known
for a long time. We are told, that the philosopher Anaxilaus even
pretended, that, by putting ink with the oil of a lamp, or the liquor
of the cuttle fish, the faces of the bystanders will appear _black_
by the light of this lamp! Sulphur has the effect of rendering the
visage pale and cadaverous. Other persons, as Simon Sethe, advanced
an opinion, that, if we moisten the wick of a lamp with ink, or in
a mixture of the rust of copper, and having lighted the wick, and
placed other lights around it, the faces will appear, some black,
and some of a brass colour. Others, such as Cardan, say, that, by
making a mixture of wine and salt, and then reducing it two-thirds
by evaporation, the flame, which the wine will then give, will make
the _living_ put on a cadaverous appearance, if they remain in one
posture. Malina also observes, that, by burning a piece of woollen
cloth well soaked in a solution of salt in vinegar, the visage will
appear frightful by the light of the flame. But the process of J. B.
Porta is not less worthy of note. If good old wine, he observes, be
put into a bowl with a handful of salt, and set on live coals, but
not in the flame, and as soon as it begins to boil, is set on fire,
(the other lights in the room being extinguished), the figure of each
person will appear so hideous, as to produce a mutual dread. The
author of the _Dictionnaire de l'Industrie_, iii, p. 433, observes,
that he has repeated this experiment, sometimes with brandy, and at
other times with alcohol, with perfect success.
A cadaverous appearance is said to be given, by mixing common salt
with alcohol, in which some saffron had been infused. When set on
fire, and the other lights extinguished, the effect, we are told, is
very striking.
The so called _miraculous luminaries_, are nothing else than solar
phosphori, which are very numerous. Their effect is to emit light in
the dark, but not heat. Almost every thing in nature possesses this
property in a greater or less degree, which depends on the absorption
and subsequent transmission of light. The eyes of various animals
have this property; cats and owls in particular. Snow possesses it
in a considerable degree. Putrid animal matter, fish, for example,
rotten wood, &c. partake also of this property.
It may not be improper to notice, in a general way, some of the
substances, which are denominated solar phosphori. The _Bolognian
phosphorus_ is the calcined baroselenite, (sulphate of barytes),
which, when exposed a few minutes to the light, shines when taken
into the dark like burning coals. In water it emits the same light.
This property, as is the case with all other solar phosphori, it
loses gradually; but by heating it again, imbibes light. _Canton's
phosphorus_ is calcined oyster shells. It is used in the same manner.
_Baldwin's phosphorus_ is fused nitrate of lime. Various saline
and other bodies, as diamonds and precious gems, possess the same
property. Expressed oils and animal fats, when heated to 450°, become
phosphorescent.
Hanzelet (_Traité des Feux d'Artifice_) remarks, that a _stone_ may
be made to give light by water, if prepared in the following manner.
Take quicklime, tutty, and saltpetre, of each one part; reduce them
to powder, and expose them to the action of heat. On the addition of
water, light is said to be given out.
When quicklime is mixed with essential oil, and brought in contact
with water, spontaneous combustion is said to take place.
Fluor or Derbyshire spar, (fluate of lime), when pulverized and
heated to 212° Fahr., and then removed to the dark, is very luminous.
If writing be made on a copper or iron plate, with thin mucilage or
white of egg, and powdered fluor spar, sprinkled on it; when the
plate is removed to a gentle coal fire, the delineated objects will
become luminous, and opaque again when the plate becomes cold. The
lapis lazuli has the same effect.
The phosphoric substances, which become luminous by attrition or
percussion, are numerous. _Homberg's phosphorus_, which is nothing
more than calcined muriate of lime, is of this character. When struck
it emits light. Without either light or fire, a number of bodies will
give out light. Flints, and other siliceous stones, struck against
one another, appear luminous in the dark. Various other minerals have
the same property. Wedgwood (_Phil. Trans._ 179,) Coates (_Nich.
Jour._ 1799,) Westrumb (_Crell's Chem. Annals_, 1784,) have written
on this subject; to which enumeration we may add the interesting
remarks of Dr. Hulme, (_Phil. Trans._ 1800,) and the observations of
Cabarris, in his Memoir, read before the National Institute.
It may be sufficient to remark, that the shell-fish called _pholas_;
the _meduca_ phosphorea, and other _molluscsæ_; several insects of
the species _fulgora_, or lantern-fly; the _lampyris_, or glowworm;
the _scolopendra electrica_; the _cancer fulgens_; the medullary
substance of the human brain, &c. are all phosphorescent.
M. Dessaignes (_Bulletin de la Société Philomatique, Octobre_, 1810)
made a number of experiments on solid, liquid, and aeriform bodies,
relative to the disengagement of light by compression. Among other
conclusions, he adds, that water is the cause of the spontaneous
phosphorescence of bodies, such as quicklime, Canton's phosphorus,
dry muriate of lime, &c. all which, when brought in contact with
water, emit light, which he attributes to the consolidation of that
fluid. The absorption of moisture, and its subsequent consolidation,
may, in some instances, give rise to luminous appearances.
The _lapis solaris_, Bolognian stone, or the present sulphate
of barytes, was discovered in 1602, by Casciorolus, a shoemaker
of Bologna. He came to Scipio Begatello, who at that time was
particularly known by his attachment to the art of gold-making, and
showed him this stone, under the mystical name of _lapis solaris_,
on account of its attracting the _golden_ light of the sun, and its
boasted fitness for converting the _semi-metals_ into gold, the _sol_
of the alchemists!
Dr. Brewster (_Edinburgh Philosophical Journal_) made a number
of experiments on the colour and intensity of light, evolved by
different minerals, by which it appears, that the yellow sulphate of
barytes gives a pale light, while fluate of lime, a blue and green
light. Cellini (_Treatise on Jewelry_, published near the beginning
of the 16th century) was the first who observed the phosphorescence
of minerals; it does not appear that he knew of the Bolognian
stone. Grimshire (_Nicholson's Journal_, 8vo. vols. 15, 16, 19,)
made a number of experiments on the emission of light by bodies,
when subjected to the electrical influence; and, when thus treated,
sulphate of barytes gave a brilliant green light.
The _cawk_ of the miners, as it is also a sulphate of barytes,
phosphoresces when previously exposed to heat.
There are two water fountains, both set in motion by the action
of heat on confined air, which, as it expands, forces the water
from an under vessel in jets. The first is called the _illuminated
fountain_, and plays when the candles are lighted, stopping when they
are extinguished. The other is a fountain, which acts on the same
principle, but by the heat of the sun. The effect of the first is
more or less considerable according to the pressure of the air upon
the water, and consequently, to the degree of rarefaction which the
air undergoes.
The _chemical illumination_ of some writers, by using oil of vitriol,
iron filings, and water, and inflaming the vapour as it proceeds from
a bottle, is nothing else than the inflammation of hydrogen gas. The
"white vapours," which they describe, is the gas in question.
Having noticed the use of candles and lamps for illumination, we
purpose, in concluding this article, to give the result of some
experiments on the relative intensities of light, and duration
of different candles, made by Dr. Ure, which we extract from his
_Dictionary of Chemistry_.
----------+----------+---------+----------+---------+---------+---------
Number | Duration | Weight | Consump. | Propor- | Economy | Candles
in a | of a | in | per hour:| tion of| of |equal one
pound. | candle. | grains. | grains. | light. | light. | argand.
----------+----------+---------+----------+---------+---------+---------
10 mould | 5 h. 9 m.| 682 | 132 | 12¼ | 68 | 5.7
10 dipped | 4 36 | 672 | 150 | 13 | 65½ | 5.25
8 mould | 6 31 | 856 | 132 | 10½ | 59½ | 6.6
6 do. | 7 2½ | 1160 | 163 | 14⅔ | 66 | 5.0
4 do. | 9 36 | 1787 | 186 | 20¼ | 80 | 3.5
Argand | | | | | |
Oil Flame | | | 512 | 69.4 | 100 |
----------+----------+---------+----------+---------+---------+---------
The doctor remarks, that 1/8th of a gallon of good seal-oil, weighs
6010 gr. or 13 and 1/10th oz. avoirdupois, and lasts, in a bright
argand lamp, 11 hours 44 minutes. The weight of oil it consumes per
hour, is equal to four times the weight of tallow in candles, 8 to
the pound, and three and one-seventh times the weight of tallow in
candles, 6 to the pound. But its light being equal to that of 5 of
the latter candles, it appears, from the above table, that 2 lbs.
weight of oil, in an argand, are equivalent, in illuminating power,
to three pounds of tallow candles. The larger the flames in the above
candles the greater the economy of light.[28]
_Sec. XXIX. Of Imitative Fire-Works._
Imitative fire-works are nearly of the same character as the
transparencies and illuminations mentioned in the last section; but,
as this subject may be interesting to some of our readers, we thought
proper for that reason to appropriate a section to its consideration.
Imitative fire-works are formed in the following manner: Take a
paper that is blacked on both sides, or instead of black, let it be
coloured on each side with a deep blue, which will be still better
for such as are to be seen through transparent papers. It must be of
a proper size for the figure intended to be exhibited. In this paper,
cut with a pen-knife several spaces, and with a piercer make a great
number of holes, rather long than round, and at no regular distance
from each other.
To represent revolving pyramids and globes, the paper must be cut
through with a pen-knife, and the space cut out between each spiral
should be three or four times as wide as the spirals themselves. They
must be so cut, that the pyramid or globe may appear to turn on its
axis. The columns that are represented in pieces of architecture, or
in jets of fire, must be cut in the same manner as if they are to be
represented as turning on their axis.
In like manner may be exhibited a great variety of ornaments,
cyphers, and medallions, which, when properly coloured, cannot fail
of producing a most pleasing effect. There should not be a very great
diversity of colours, as that would not produce the most agreeable
appearance.
When these pieces are drawn upon a large scale, the architecture or
ornaments may be shaded; and to represent different shades, pieces of
coloured paper must be pasted over each other, which will produce an
effect that would not be expected from transparent paintings. Five or
six pieces of paper, pasted over each other, will be sufficient to
represent the strongest shades. To give these pieces the different
motions they require, we must first consider the nature of each
piece: if, for example, we have cut out the figure of the sun, or
of a star, we must construct a wire wheel of the same diameter with
those pieces. Over this wheel a very thin paper is to be pasted,
on which is drawn with black ink the spiral figure. The wheel thus
prepared, is to be placed behind the sun or star, in such a manner
that its axis may be exactly opposite the centre of either of those
figures. This wheel may be turned by any contrivance.
Now, the wheel being placed directly behind the sun, for example,
and very near to it, is to be turned regularly round and strongly
illuminated by candles placed behind it. The lines that form the
spiral will then appear through the spaces cut from the sun, to
proceed from its centre to its circumference; and will resemble
sparks of fire that incessantly succeed each other. The same effect
will be produced by the star, or by any other figure, where the fire
is not to appear as proceeding from the circumference to the centre.
These two pieces, as well as those that follow, may be of any size,
provided we observe the proportion between the parts of the figure
and the spiral, which must be wider in large figures than in small.
If the sun, for example, have from six to twelve inches diameter,
the width of the strokes that form the spiral need not be more than
one-twentieth part of an inch, and the spaces between them that form
the transparent parts, about two-tenths of an inch. If the sun be two
feet in diameter, the strokes should be one-eighth of an inch, and
the space between, one quarter of an inch; and if the figure be six
feet in diameter, the strokes should be one-fourth of an inch, and
the spaces, five-twelfths of an inch. These pieces have a pleasing
effect, when represented of a small size; but the deception is more
striking when they are of larger dimensions.
It will be proper to place these pieces, when of a small size, in a
box quite close on every side, that none of the light may be diffused
in the chamber; for which purpose it will be convenient to have a tin
door behind the box, to which the candlesticks may be soldered, and
the candles more easily lighted.
The several figures cut out should be placed in frames, that they may
be put alternately in a groove in the forepart of the box, or there
may be two grooves, that the second piece may be put in before the
first is taken out.
The wheel must be carefully concealed from the eye of the spectator.
Where there is an opportunity of representing these artificial fires
by a hole in the partition, they will doubtless have a much more
striking effect, as the spectator cannot then conjecture by what
means they are produced.
It is easy to conceive, that, by extending this method, wheels may
be constructed with three or four spirals, to which may be given
different directions. It is manifest, also, that, on the same
principle, a great variety of transparent figures may be contrived,
which may be all placed before the same spiral lines.
In representing cascades of fire, it is necessary to observe, that,
in cutting out the cascades, care must be taken to preserve a natural
inequality in the parts cut out; for if to save time, all the holes
are made with the same pointed tool, the uniformity of the parts will
produce a disagreeable effect.
To produce the apparent motion of these cascades, instead of drawing
a spiral, a slip of strong paper is to be provided, in which there
must be made a great number of holes near each other, and made with
pointed tools of different dimensions.
At each end of the paper, a part, of the same size with the cascade,
must be left uncut; and towards those parts the holes must be made a
greater distance from each other.
When the cascade that is cut out is placed before the scroll of paper
just mentioned, and it is entirely wound upon the roller, the part
of the paper that is then between, being quite opaque, no part of
the cascade will be visible; but, as the wheel is turned gently and
regularly round, the transparent part of the paper will give to the
cascade the appearance of fire that descends in the same direction;
and the illusion will be so strong, as to appear as a real cascade of
fire.