GLASS-CUTTING.

GLASS-CUTTING.GLASS-CUTTING.The kind of glass generally used for ornamental cutting is flint-glass. Decanters, wine-glasses, &c., are also made of it; it is very bright, white, and easily cut. Glass is cut by means of wheels of different sizes and materials, turned by a treadle, as in a common lathe; some are made of fine sandstone, some of iron, others of tin or copper; the edges of some are square, some round, and some are sharp. They are used with sand and water, or emery and water, but stone wheels are used with water only. The glass-cutter also uses rods of copper with knobs at their ends, for making round indentations; these turn on their axis, so that the end cuts a round hollow in the glass. The work is at first cut roughly, afterwards smoothed off with the sandstone or tin wheel (the latter has to be smeared with emery and water), and finally polished by a wooden wheel with finely-powdered pumice-stone applied to its edge, and moistened with water. The glasses for spectacles and optical instruments are cut by concave or convex moulds of brass moistened with emery and water, and polished by means of a mould of pitch wetted with crocus and water. Great art and accuracy are required to grind the glasses for optical instruments, especially very large or very small ones, as for microscopes, the various “powers” of which constitute their chief expense—one of the sixteenth of an inch in diameter costing about twelve pounds.

GLASS-CUTTING.

The kind of glass generally used for ornamental cutting is flint-glass. Decanters, wine-glasses, &c., are also made of it; it is very bright, white, and easily cut. Glass is cut by means of wheels of different sizes and materials, turned by a treadle, as in a common lathe; some are made of fine sandstone, some of iron, others of tin or copper; the edges of some are square, some round, and some are sharp. They are used with sand and water, or emery and water, but stone wheels are used with water only. The glass-cutter also uses rods of copper with knobs at their ends, for making round indentations; these turn on their axis, so that the end cuts a round hollow in the glass. The work is at first cut roughly, afterwards smoothed off with the sandstone or tin wheel (the latter has to be smeared with emery and water), and finally polished by a wooden wheel with finely-powdered pumice-stone applied to its edge, and moistened with water. The glasses for spectacles and optical instruments are cut by concave or convex moulds of brass moistened with emery and water, and polished by means of a mould of pitch wetted with crocus and water. Great art and accuracy are required to grind the glasses for optical instruments, especially very large or very small ones, as for microscopes, the various “powers” of which constitute their chief expense—one of the sixteenth of an inch in diameter costing about twelve pounds.

BRICKLAYING.BRICKLAYING.(‡ Unstable Stacking Of Bricks.)FIG.1.(‡ English Bond.)FIG.2.(‡ Flemish Bond.)FIG.3.(‡ Plumb.)FIG.4.(‡ TROWEL.)FIG.5.(‡ Hod.)FIG.6.Nearly all houses are built of bricks, as they are less expensive than stone, and more durable than wood, besides being less liable to be burnt. Walls of brick may be formed of any required thickness, and as the length of a brick is twice its breadth, they admit of being so laid that the wall shall not part in pieces, which would be the case if laid as infig. 1, as the seams of mortar run continuously through the wall, which in bricklaying is always avoided, by different methods. Formerly bricks were laid in what was called “English bond” (fig. 2), but this is not now used, “Flemish bond” (fig. 3) having superseded it. The mortar with which bricks are laid is made of lime and sand, mixed with water to a convenient consistence; it sets quickly, hardens with age, and resists the action of rain and time. The ordinary mode of laying bricks is to stretch a line from end to end of the course on which they are to be laid; the surface of the under course is spread for a short distance with mortar, and the bricks intended to form the outer surface of the wall are laid first, in an exact line with the cord, the “plumb” (fig. 4) being frequently used to ascertain if they are perpendicular. The “plumb” is a piece of board with a notch at the centre of the top, and a hole, also in the centre, near the bottom; a piece of cord is passed through the notch, with a leaden ball attached, which swings in the hole as the plumb is placed at the side of the wall. The ball of lead just falls in the hole if the wall is upright, and in this way a wall may be built to any height, exactly perpendicular. The corner of brickwork where windows occur, is called the “arris,” and has to be made upright both in front and at the side. When very thick walls are to be made (as in railway cuttings), the outer surface and back of the walls are laid in the usual way, the space between is filled with a layer of bricks, and thin liquid mortar is poured on and scraped about with a sort of hoe till the spaces between the bricks are all filled up and the surface left level, when another course is laid in the same manner.Fig. 5is a trowel, or instrument used to take up and spread out the mortar, andfig. 6is the hod, in which the labourer carries supplies of bricks or mortar to the spot where the bricklayer is working.

BRICKLAYING.

(‡ Unstable Stacking Of Bricks.)FIG.1.(‡ English Bond.)FIG.2.(‡ Flemish Bond.)FIG.3.

(‡ Unstable Stacking Of Bricks.)FIG.1.

FIG.1.

(‡ English Bond.)FIG.2.

FIG.2.

(‡ Flemish Bond.)FIG.3.

FIG.3.

(‡ Plumb.)FIG.4.(‡ TROWEL.)FIG.5.(‡ Hod.)FIG.6.

(‡ Plumb.)FIG.4.

FIG.4.

(‡ TROWEL.)FIG.5.

FIG.5.

(‡ Hod.)FIG.6.

FIG.6.

Nearly all houses are built of bricks, as they are less expensive than stone, and more durable than wood, besides being less liable to be burnt. Walls of brick may be formed of any required thickness, and as the length of a brick is twice its breadth, they admit of being so laid that the wall shall not part in pieces, which would be the case if laid as infig. 1, as the seams of mortar run continuously through the wall, which in bricklaying is always avoided, by different methods. Formerly bricks were laid in what was called “English bond” (fig. 2), but this is not now used, “Flemish bond” (fig. 3) having superseded it. The mortar with which bricks are laid is made of lime and sand, mixed with water to a convenient consistence; it sets quickly, hardens with age, and resists the action of rain and time. The ordinary mode of laying bricks is to stretch a line from end to end of the course on which they are to be laid; the surface of the under course is spread for a short distance with mortar, and the bricks intended to form the outer surface of the wall are laid first, in an exact line with the cord, the “plumb” (fig. 4) being frequently used to ascertain if they are perpendicular. The “plumb” is a piece of board with a notch at the centre of the top, and a hole, also in the centre, near the bottom; a piece of cord is passed through the notch, with a leaden ball attached, which swings in the hole as the plumb is placed at the side of the wall. The ball of lead just falls in the hole if the wall is upright, and in this way a wall may be built to any height, exactly perpendicular. The corner of brickwork where windows occur, is called the “arris,” and has to be made upright both in front and at the side. When very thick walls are to be made (as in railway cuttings), the outer surface and back of the walls are laid in the usual way, the space between is filled with a layer of bricks, and thin liquid mortar is poured on and scraped about with a sort of hoe till the spaces between the bricks are all filled up and the surface left level, when another course is laid in the same manner.Fig. 5is a trowel, or instrument used to take up and spread out the mortar, andfig. 6is the hod, in which the labourer carries supplies of bricks or mortar to the spot where the bricklayer is working.

STONE CUTTING.STONE-CUTTING.(‡ Iron Pick.)FIG.1.(‡ Chisel And Scraper.)FIG.2.Some stones, as “Bath stone” can be cut with a common toothed saw, and are but little harder than chalk; others, as marble, Portland stone, &c., require to be cut with a flat blade of iron stretched in a frame and having a supply of sand and water. A man sits in a shed having this heavy saw suspended from two poles, and balanced by a piece of stone swung over a pulley; he alternately pushes and pulls the frame, allowing the water to trickle into the seam as it forms, the sand being rubbed between the edge of the saw and the stone as the saw is moved backwards and forwards, slowly cutting the stone (seeillustration). By this slow and tedious process building stones are cut into squares, slices, slabs, or any other form required. Granite is too hard for even this slow process, and after the pieces are chosen as nearly as can be got of the size and shape required, they are worked with a heavy iron pick (fig. 1), which at each blow strikes off a little piece not bigger than a pea, by which method the stone is shaped into the form required. Smaller cuttings of stone for building purposes, such as carvings, &c., are formed by the mallet and chisel (fig. 2), the work being finished with a rasp or steel scraper.

STONE-CUTTING.

(‡ Iron Pick.)FIG.1.

FIG.1.

(‡ Chisel And Scraper.)FIG.2.

FIG.2.

Some stones, as “Bath stone” can be cut with a common toothed saw, and are but little harder than chalk; others, as marble, Portland stone, &c., require to be cut with a flat blade of iron stretched in a frame and having a supply of sand and water. A man sits in a shed having this heavy saw suspended from two poles, and balanced by a piece of stone swung over a pulley; he alternately pushes and pulls the frame, allowing the water to trickle into the seam as it forms, the sand being rubbed between the edge of the saw and the stone as the saw is moved backwards and forwards, slowly cutting the stone (seeillustration). By this slow and tedious process building stones are cut into squares, slices, slabs, or any other form required. Granite is too hard for even this slow process, and after the pieces are chosen as nearly as can be got of the size and shape required, they are worked with a heavy iron pick (fig. 1), which at each blow strikes off a little piece not bigger than a pea, by which method the stone is shaped into the form required. Smaller cuttings of stone for building purposes, such as carvings, &c., are formed by the mallet and chisel (fig. 2), the work being finished with a rasp or steel scraper.

APPARATUS AND MACHINERY.STEAM-ENGINES.BEAM OF STEAM ENGINE, WOOLWICH ARSENAL.The great improvements in machinery—whether for looms, locomotive engines, or steam-ships, for forging anchors, boring cannon, rolling out and rivetting iron plates together for tubular bridges and boilers, or any other kind of work—are chiefly owing to the wonderful ease with which these machines can be driven by the power of steam. It matters not whether the object to be wrought is the head of a pin, or the crank of a steam-ship, it is done with both delicacy of touch and power of arm, a hundredfold beyond what could be effected by hand in the same time. The motive power of steam is derived from the property which water has of being expanded into vapour when heated to a certain degree, and of again resuming the form of water when cooled; this moreover takes place in the most easily manageable manner, and either by degrees or suddenly, according as the heat and pressure balance each other; moreover water, being easily obtained, and in sufficient quantity for the purpose, in all places where machinery is required, can always be applied. Before the use of steam, wind, water, horse, and hand power were chiefly in use; water-mills were, of course, only erected in those situations where a good supply of water could be obtained, and this even often failed in dry weather; windmills also depended on that uncertain element. Horse and hand powers are limited in their extent, and are moreover very expensive. The first attempts at a steam-engine were those in which the steam was only used that by its condensation a vacuum might be formed in a cylinder under a piston, so that the weight of the air should cause this to descend with considerable force—15 lbs. on the square inch. The piston was balanced by a weight, so that the steam might raise it with scarcely any pressure; the steam beneath the piston being condensed by a stream of cold water, the weight of the air again forced down the piston into the vacuum. This therefore was not a steam but an air-engine, as all the power exerted was derived from the weight of the air, and the steam merely used to procure a vacuum. After this came the low-pressure or condensing engine, and then the high-pressure or non-condensing engine, both of which are now used, the former in marine engines and the latter in locomotives.FIG.2. BOILERS, WOOLWICH ARSENAL.FLY-WHEEL, WOOLWICH ARSENAL.FIG.1. BOILERS, WOOLWICH ARSENAL.The steam-engine consists essentially of a boiler or steam-generator, with a furnace adapted to it, connected by a steam-pipe to a cylinder having a piston working accurately in it, and valves so contrived that the steam shall enter alternately above and below the piston. In the condensing engine, each compartment, above and below the piston, communicates with the condenser—the vessel in which the steam is suddenly condensed by cold water—and the valves are so arranged that when the steam enters above the piston, the space below is opened to the condenser, and is therefore a partial vacuum; by the time the piston is driven down by the force of the steam above it, the space is shut off from the condenser and opened to the steam-pipe, while the space above is shut off from the steam-pipe and opened to the condenser. In this way one side of the piston is alternately pressed by the steam while there is a vacuum on the other side. In the non-condensing engine the space above and below the piston is alternately pressed by steam at a great degree of tension; while at the opposite side of the piston, the space is opened to the air by a valve. These valves are what are called “sliding valves,” being both in connection with the same action, which shuts one while it opens the other; that is, when the piston has nearly descended, it slides the valve which shuts off the steam from the space above and opens it to the air, the same action opening the steam-valve below the piston and shutting it from the air. In this kind of engine the piston is moved simply by the power of the steam, which first presses it down and then presses it up again, and as the steam escapes at each stroke of the piston, and has to be at a great tension or pressure, a large and rapidly-formed supply of steam is required. In the locomotive and other high-pressure engines this is effected by having a great number of tubes passing through the boiler leading from the fire-place to the flue, so that the fire and heated air shall pass through them before reaching the flue, and consequently, as these all pass through the water in the boiler, producing a very rapid generation of steam. Of the various forms of boilers, the most simple was that in which the heat was merely applied to the lower part (fig. 1); next may be named the wagon-head boiler, in which the flue passed all round; some were made with a cylindrical flue passing though the whole length, and some with two (fig. 2). Of whatever form the boiler may be, it should be strong enough to well resist the pressure of the steam, but to make this sure, a contrivance called a safety-valve is always used; this consists of a valve held down by a weight, which would be raised by the steam if it should press so hard as to endanger the boiler in the least degree; when the safety-valve is forced up, the steam escapes and the pressure is taken off. Most steam engines require the up-and-down motion of the piston to be converted into a circular motion, and this is effected by means of a “crank,” (see “Cranks”); but this circular motion needs in most cases to be regulated by a fly-wheel which is so heavy, that upon being set in motion it continues to revolve for a time by its own weight, so that the intermitting pulls exerted by the piston-rod on the crank are blended into one continuous action (seecut); but in steam-ships, and locomotive engines, fly-wheels cannot be used. In these cases there are two cylinders and pistons, each fixed to a crank formed in one axle united to the two wheels, and these cranks are so arranged that the greatest power is exerted on one when the least is exerted on the other, and for this purpose they are placed so that when one crank is upright the other is horizontal. The stroke of the piston-rod is not always made to act directly on the crank, but has a “beam” interposed working on bearings in its centre, hence the term beam-engine (seecut). This beam moves the crank at the opposite end to that which is moved by the piston and at the same time works the air-pump, feed-pump, and cold-water-pump, by means of jointed rods.(‡ Governor.)FIG.3.In those engines which have to perform unequal work, and in which sometimes a great drag is suddenly removed from the engine, some contrivance is necessary to prevent the too rapid motion which would ensue, to the great risk of damaging the engine; this is effected by what is called the “governor;” a contrivance by which a part of the steam is struck off when the action is too rapid, and again let on when it has diminished. This arrangement is shown infig. 3; the two heavy iron balls swing round as the engine works, and the faster they revolve the more they tend to separate, from the natural tendency to fly off called “centrifugal force,” and in separating they bring the other ends of the rods to which they are attached nearer together, and so push up a collar,A, attached to the levers which turn off the steam-tap; and as the action subsides the balls sink down together and the collar also, the steam being thus turned on again. In order that the pressure of the steam in the boiler may be known, a “gauge” is used, which acts on the principle of the barometer, consisting of a column of mercury which is pressed up by the force of the steam, the height to which it rises indicating the pressure. With respect to the details of the steam-engine, they are too various and complicated to be enumerated or described here; but the motion—being regular, continuous, and powerful—can be applied to almost any sort of work by being adapted to the machine suitable for such work, and which receives its motion from the steam-engine, the same as though it were worked by water or by hand.

BEAM OF STEAM ENGINE, WOOLWICH ARSENAL.

The great improvements in machinery—whether for looms, locomotive engines, or steam-ships, for forging anchors, boring cannon, rolling out and rivetting iron plates together for tubular bridges and boilers, or any other kind of work—are chiefly owing to the wonderful ease with which these machines can be driven by the power of steam. It matters not whether the object to be wrought is the head of a pin, or the crank of a steam-ship, it is done with both delicacy of touch and power of arm, a hundredfold beyond what could be effected by hand in the same time. The motive power of steam is derived from the property which water has of being expanded into vapour when heated to a certain degree, and of again resuming the form of water when cooled; this moreover takes place in the most easily manageable manner, and either by degrees or suddenly, according as the heat and pressure balance each other; moreover water, being easily obtained, and in sufficient quantity for the purpose, in all places where machinery is required, can always be applied. Before the use of steam, wind, water, horse, and hand power were chiefly in use; water-mills were, of course, only erected in those situations where a good supply of water could be obtained, and this even often failed in dry weather; windmills also depended on that uncertain element. Horse and hand powers are limited in their extent, and are moreover very expensive. The first attempts at a steam-engine were those in which the steam was only used that by its condensation a vacuum might be formed in a cylinder under a piston, so that the weight of the air should cause this to descend with considerable force—15 lbs. on the square inch. The piston was balanced by a weight, so that the steam might raise it with scarcely any pressure; the steam beneath the piston being condensed by a stream of cold water, the weight of the air again forced down the piston into the vacuum. This therefore was not a steam but an air-engine, as all the power exerted was derived from the weight of the air, and the steam merely used to procure a vacuum. After this came the low-pressure or condensing engine, and then the high-pressure or non-condensing engine, both of which are now used, the former in marine engines and the latter in locomotives.

FIG.2. BOILERS, WOOLWICH ARSENAL.

FLY-WHEEL, WOOLWICH ARSENAL.

FIG.1. BOILERS, WOOLWICH ARSENAL.

The steam-engine consists essentially of a boiler or steam-generator, with a furnace adapted to it, connected by a steam-pipe to a cylinder having a piston working accurately in it, and valves so contrived that the steam shall enter alternately above and below the piston. In the condensing engine, each compartment, above and below the piston, communicates with the condenser—the vessel in which the steam is suddenly condensed by cold water—and the valves are so arranged that when the steam enters above the piston, the space below is opened to the condenser, and is therefore a partial vacuum; by the time the piston is driven down by the force of the steam above it, the space is shut off from the condenser and opened to the steam-pipe, while the space above is shut off from the steam-pipe and opened to the condenser. In this way one side of the piston is alternately pressed by the steam while there is a vacuum on the other side. In the non-condensing engine the space above and below the piston is alternately pressed by steam at a great degree of tension; while at the opposite side of the piston, the space is opened to the air by a valve. These valves are what are called “sliding valves,” being both in connection with the same action, which shuts one while it opens the other; that is, when the piston has nearly descended, it slides the valve which shuts off the steam from the space above and opens it to the air, the same action opening the steam-valve below the piston and shutting it from the air. In this kind of engine the piston is moved simply by the power of the steam, which first presses it down and then presses it up again, and as the steam escapes at each stroke of the piston, and has to be at a great tension or pressure, a large and rapidly-formed supply of steam is required. In the locomotive and other high-pressure engines this is effected by having a great number of tubes passing through the boiler leading from the fire-place to the flue, so that the fire and heated air shall pass through them before reaching the flue, and consequently, as these all pass through the water in the boiler, producing a very rapid generation of steam. Of the various forms of boilers, the most simple was that in which the heat was merely applied to the lower part (fig. 1); next may be named the wagon-head boiler, in which the flue passed all round; some were made with a cylindrical flue passing though the whole length, and some with two (fig. 2). Of whatever form the boiler may be, it should be strong enough to well resist the pressure of the steam, but to make this sure, a contrivance called a safety-valve is always used; this consists of a valve held down by a weight, which would be raised by the steam if it should press so hard as to endanger the boiler in the least degree; when the safety-valve is forced up, the steam escapes and the pressure is taken off. Most steam engines require the up-and-down motion of the piston to be converted into a circular motion, and this is effected by means of a “crank,” (see “Cranks”); but this circular motion needs in most cases to be regulated by a fly-wheel which is so heavy, that upon being set in motion it continues to revolve for a time by its own weight, so that the intermitting pulls exerted by the piston-rod on the crank are blended into one continuous action (seecut); but in steam-ships, and locomotive engines, fly-wheels cannot be used. In these cases there are two cylinders and pistons, each fixed to a crank formed in one axle united to the two wheels, and these cranks are so arranged that the greatest power is exerted on one when the least is exerted on the other, and for this purpose they are placed so that when one crank is upright the other is horizontal. The stroke of the piston-rod is not always made to act directly on the crank, but has a “beam” interposed working on bearings in its centre, hence the term beam-engine (seecut). This beam moves the crank at the opposite end to that which is moved by the piston and at the same time works the air-pump, feed-pump, and cold-water-pump, by means of jointed rods.

(‡ Governor.)FIG.3.

FIG.3.

In those engines which have to perform unequal work, and in which sometimes a great drag is suddenly removed from the engine, some contrivance is necessary to prevent the too rapid motion which would ensue, to the great risk of damaging the engine; this is effected by what is called the “governor;” a contrivance by which a part of the steam is struck off when the action is too rapid, and again let on when it has diminished. This arrangement is shown infig. 3; the two heavy iron balls swing round as the engine works, and the faster they revolve the more they tend to separate, from the natural tendency to fly off called “centrifugal force,” and in separating they bring the other ends of the rods to which they are attached nearer together, and so push up a collar,A, attached to the levers which turn off the steam-tap; and as the action subsides the balls sink down together and the collar also, the steam being thus turned on again. In order that the pressure of the steam in the boiler may be known, a “gauge” is used, which acts on the principle of the barometer, consisting of a column of mercury which is pressed up by the force of the steam, the height to which it rises indicating the pressure. With respect to the details of the steam-engine, they are too various and complicated to be enumerated or described here; but the motion—being regular, continuous, and powerful—can be applied to almost any sort of work by being adapted to the machine suitable for such work, and which receives its motion from the steam-engine, the same as though it were worked by water or by hand.

BOILERS.Boilers are vessels in which fluids are boiled or heated, and are almost of every form and size. Some boilers, such as those attached to steam-engines, are more strictly called “steam generators,” as they are constructed solely for the production of steam at the lowest possible expense of time and fuel, and also to resist the pressure which the steam exerts at high temperatures; these boilers are not only used to produce the steam for the motion of engines, but are extensively used in its production for heating evaporating-pans and boilers (in the strict sense of the word), and also for warming and ventilating buildings. They are more particularly noticed under the head “Steam Engines.”Boilers for all purposes were formerly made of metal (usually copper or iron), and were exposed directly to the fire intended to heat their contents, but since the properties of steam have been more fully recognised, it is now very frequently employed for heating boilers—especially where a heat at or below the boiling point of water is required. There are great advantages arising from this plan, one of which consists in doing away with the risk of the materials in the boiler being burnt. Some boilers are now made of wood, having steam-pipes running through them, and in those cases in which the admixture of water is no detriment steam—in the form of jets—is thrown directly into the fluid to be heated, which very quickly raises it to the boiling point. Boilers of cast-iron, lined with platinum or enamel, are also used for various purposes, as the condensation of acid substances, &c., which would act on most metals. Glass and glazed pans, too, can be used with a steam apparatus, without any danger arising from breakage, which would frequently occur if they were directly applied to the fire.

Boilers are vessels in which fluids are boiled or heated, and are almost of every form and size. Some boilers, such as those attached to steam-engines, are more strictly called “steam generators,” as they are constructed solely for the production of steam at the lowest possible expense of time and fuel, and also to resist the pressure which the steam exerts at high temperatures; these boilers are not only used to produce the steam for the motion of engines, but are extensively used in its production for heating evaporating-pans and boilers (in the strict sense of the word), and also for warming and ventilating buildings. They are more particularly noticed under the head “Steam Engines.”

Boilers for all purposes were formerly made of metal (usually copper or iron), and were exposed directly to the fire intended to heat their contents, but since the properties of steam have been more fully recognised, it is now very frequently employed for heating boilers—especially where a heat at or below the boiling point of water is required. There are great advantages arising from this plan, one of which consists in doing away with the risk of the materials in the boiler being burnt. Some boilers are now made of wood, having steam-pipes running through them, and in those cases in which the admixture of water is no detriment steam—in the form of jets—is thrown directly into the fluid to be heated, which very quickly raises it to the boiling point. Boilers of cast-iron, lined with platinum or enamel, are also used for various purposes, as the condensation of acid substances, &c., which would act on most metals. Glass and glazed pans, too, can be used with a steam apparatus, without any danger arising from breakage, which would frequently occur if they were directly applied to the fire.

FURNACES.(‡ Reverberatory Furnace.)FIG.1.(‡ Blast Furnace.)FIG.2.(‡ Cutaway Diagram Of Blast Furnace.)FIG.3.Furnaces are fire-places constructed to serve particular purposes, and are chiefly of two kinds, “Wind furnaces” and “Blast furnaces.” Of the first kind the common house grate is an instance, of the second the blacksmith’s forge. The fire in a wind furnace is more or less shut up, so that the draught of air entering it shall pass from the ash-pit right up into the fire, and through it into the flue or chimney—the latter being tall, and of certain proportions, so as to ensure the requisite draught. These furnaces are used where heat of the very highest degree is not required, as in glass-houses, pottery-kilns, &c. The “Reverberatory furnace” is a modification of the wind furnace, and is used to throw heat on to the surface of substances, as in roasting ores of metals, to drive off the sulphur, arsenic, &c., or in the making of soda, litharge, and other processes where the admission of hot air with the flame is either beneficial, or at least not detrimental;fig. 1shows the construction of this kind of furnace. Blast furnaces are for the production of the very highest degrees of temperature, and in these the air is forced into the fire by blowing machines or bellows, often worked by steam-engines; such furnaces are used for the smelting and casting of iron, &c. (fig. 2). A good blast furnace for small purposes may be made by two crucibles—those made of coarse blacklead and clay, and called “Blue pots,” are the best—one placed inside the other, the outer one having a hole at the lower part for the nose of the bellows, the inner one having the bottom cut off and a grating of iron put in to lodge just above the lowest part; the space between the two should be filled with powdered fire-brick or broken-up crucibles (fig. 3).

(‡ Reverberatory Furnace.)FIG.1.

FIG.1.

(‡ Blast Furnace.)FIG.2.(‡ Cutaway Diagram Of Blast Furnace.)FIG.3.

(‡ Blast Furnace.)FIG.2.

FIG.2.

(‡ Cutaway Diagram Of Blast Furnace.)FIG.3.

FIG.3.

Furnaces are fire-places constructed to serve particular purposes, and are chiefly of two kinds, “Wind furnaces” and “Blast furnaces.” Of the first kind the common house grate is an instance, of the second the blacksmith’s forge. The fire in a wind furnace is more or less shut up, so that the draught of air entering it shall pass from the ash-pit right up into the fire, and through it into the flue or chimney—the latter being tall, and of certain proportions, so as to ensure the requisite draught. These furnaces are used where heat of the very highest degree is not required, as in glass-houses, pottery-kilns, &c. The “Reverberatory furnace” is a modification of the wind furnace, and is used to throw heat on to the surface of substances, as in roasting ores of metals, to drive off the sulphur, arsenic, &c., or in the making of soda, litharge, and other processes where the admission of hot air with the flame is either beneficial, or at least not detrimental;fig. 1shows the construction of this kind of furnace. Blast furnaces are for the production of the very highest degrees of temperature, and in these the air is forced into the fire by blowing machines or bellows, often worked by steam-engines; such furnaces are used for the smelting and casting of iron, &c. (fig. 2). A good blast furnace for small purposes may be made by two crucibles—those made of coarse blacklead and clay, and called “Blue pots,” are the best—one placed inside the other, the outer one having a hole at the lower part for the nose of the bellows, the inner one having the bottom cut off and a grating of iron put in to lodge just above the lowest part; the space between the two should be filled with powdered fire-brick or broken-up crucibles (fig. 3).

BELLOWS AND BLOWING MACHINES.(‡ Blacksmith Bellow.)FIG.1.(‡ Double-Bellow.)FIG.2.(‡ Fan Wheel.)FIG.3.(‡ Fan Wheel Housing.)FIG.4.The common bellows is the most familiar form of blowing machine. It consists of two boards bound together with leather, having folds so arranged that the upper board may be raised or depressed, and the whole is made air-tight; in the lower board is a hole with a leather flap-valve opening inwards. When the upper board is raised, the air rushes in at the hole, pushing up the valve, and when the board is lowered the air presses the valve down, and so shuts it close, it has therefore no exit but at the nose of the bellows, from which it passes out. Blacksmiths’ bellows (fig. 1) are made double, for the purpose of keeping up a continuous stream of air, instead of the separate puffs produced by the common single bellows. The arrangement of the double bellows is as follows:—There are three boards bound together with leather folded as in the common house bellows; the board in the middle is fixed, and to this the nose is fastened, but it opens only into the space above; the upper and lower boards are united to the middle one by a hinge, and are capable of being moved up and down; the middle and lower ones have each holes and valves opening upwards as in the common bellows, and when the lower board is raised it presses the air in the space between it and the middle board through the hole in the latter, into the space between it and the upper one, and so raises it; this has a heavy iron weight placed on it which makes it sink down and force the air out through the nose. While this weight is sinking the lower board is pushed down, and is ready to force a fresh quantity of air into the upper space, so that one continuous stream of air issues at the nose of the bellows. The handle is fixed to the lower board, and generally has a cord uniting it to a wooden handle, which is worked like a pump-handle (fig. 2). For large furnaces, blowing machines of various kinds are used, generally consisting of a pair of large cylinders having pistons worked in them by steam power, and pumping air into a large air-chamber, from which it proceeds in three or four pipes to the furnace, or sometimes to numerous furnaces, each having a tube and stop-cock by which the “blast” may be turned on, similarly to gas or water, the air-chamber being always kept filled at a great pressure by the cylinders, and furnished with a safety-valve to prevent the pressure bursting it. There is another kind of blowing-machine, consisting of a fan wheel turning very rapidly in a round box (figs. 3and4), from which a tube proceeds, and having holes in the sides to admit the air, which is thrown forwards by the fans of the wheel.

(‡ Blacksmith Bellow.)FIG.1.(‡ Double-Bellow.)FIG.2.

(‡ Blacksmith Bellow.)FIG.1.

FIG.1.

(‡ Double-Bellow.)FIG.2.

FIG.2.

(‡ Fan Wheel.)FIG.3.(‡ Fan Wheel Housing.)FIG.4.

(‡ Fan Wheel.)FIG.3.

FIG.3.

(‡ Fan Wheel Housing.)FIG.4.

FIG.4.

The common bellows is the most familiar form of blowing machine. It consists of two boards bound together with leather, having folds so arranged that the upper board may be raised or depressed, and the whole is made air-tight; in the lower board is a hole with a leather flap-valve opening inwards. When the upper board is raised, the air rushes in at the hole, pushing up the valve, and when the board is lowered the air presses the valve down, and so shuts it close, it has therefore no exit but at the nose of the bellows, from which it passes out. Blacksmiths’ bellows (fig. 1) are made double, for the purpose of keeping up a continuous stream of air, instead of the separate puffs produced by the common single bellows. The arrangement of the double bellows is as follows:—There are three boards bound together with leather folded as in the common house bellows; the board in the middle is fixed, and to this the nose is fastened, but it opens only into the space above; the upper and lower boards are united to the middle one by a hinge, and are capable of being moved up and down; the middle and lower ones have each holes and valves opening upwards as in the common bellows, and when the lower board is raised it presses the air in the space between it and the middle board through the hole in the latter, into the space between it and the upper one, and so raises it; this has a heavy iron weight placed on it which makes it sink down and force the air out through the nose. While this weight is sinking the lower board is pushed down, and is ready to force a fresh quantity of air into the upper space, so that one continuous stream of air issues at the nose of the bellows. The handle is fixed to the lower board, and generally has a cord uniting it to a wooden handle, which is worked like a pump-handle (fig. 2). For large furnaces, blowing machines of various kinds are used, generally consisting of a pair of large cylinders having pistons worked in them by steam power, and pumping air into a large air-chamber, from which it proceeds in three or four pipes to the furnace, or sometimes to numerous furnaces, each having a tube and stop-cock by which the “blast” may be turned on, similarly to gas or water, the air-chamber being always kept filled at a great pressure by the cylinders, and furnished with a safety-valve to prevent the pressure bursting it. There is another kind of blowing-machine, consisting of a fan wheel turning very rapidly in a round box (figs. 3and4), from which a tube proceeds, and having holes in the sides to admit the air, which is thrown forwards by the fans of the wheel.

SCREW PROPELLERS.SCREW STEAM-VESSEL.FIG.1. SCREW STEAM-VESSEL, SHOWING THE FAN.(‡ Propeller.)FIG.2.These are instruments placed at the back part of steam-vessels for the purpose of propelling them through the water.Fig. 1will show the position they occupy, andfig. 2the shape of the propeller. When first used, they had one or two entire turns round the axis, but are now made with two blades, each forming about one-sixth part only of one turn, and this is found to give more power with less friction. The propeller is turned rapidly round in the water, from which it meets with resistance in a direction perpendicular to the surface of its blades, but as this is oblique to the direction of rotation the force is exerted in two directions, one directly opposes this rotation, and is overcome by the power of the steam-engine, the other is in a direction towards the ship, overcoming the inertia of the vessel and the friction and resistance of the water, so that the ship is moved along, and the propeller winds its way through the water in a spiral direction as an ordinary screw does through the hollow screw made to fit it, the vessel travelling at a speed proportionate to the screw’s revolutions.

SCREW STEAM-VESSEL.

FIG.1. SCREW STEAM-VESSEL, SHOWING THE FAN.

(‡ Propeller.)FIG.2.

FIG.2.

These are instruments placed at the back part of steam-vessels for the purpose of propelling them through the water.Fig. 1will show the position they occupy, andfig. 2the shape of the propeller. When first used, they had one or two entire turns round the axis, but are now made with two blades, each forming about one-sixth part only of one turn, and this is found to give more power with less friction. The propeller is turned rapidly round in the water, from which it meets with resistance in a direction perpendicular to the surface of its blades, but as this is oblique to the direction of rotation the force is exerted in two directions, one directly opposes this rotation, and is overcome by the power of the steam-engine, the other is in a direction towards the ship, overcoming the inertia of the vessel and the friction and resistance of the water, so that the ship is moved along, and the propeller winds its way through the water in a spiral direction as an ordinary screw does through the hollow screw made to fit it, the vessel travelling at a speed proportionate to the screw’s revolutions.

ANCHORS.(‡ Anchor With Wood Stock.)FIG.1.(‡ Anchor With Iron Stock.)FIG.2.(‡ Space-Saving Anchor.)FIG.3.(‡ Anchor At Rest.)FIG.4.(‡ “Weighing” Anchor.)FIG.5.These ponderous instruments are used for the purpose of securing ships and other vessels, that they may not be driven onwards by the wind or tide. They are attached to a strong rope or chain, called the “cable,” and when not in use are kept swung at the fore-part or bow of a ship, the cable being wound round an apparatus called the capstan, which serves to let it out or draw it in. Anchors are made of iron, and are of the form delineated infig. 1. The straight part from the ring to the bend is called the “shank,” the curved part is made up of the two “arms,” and the centre where it joins the shank is called the “crown.” At the end of each arm is a plate of iron of triangular form, called a “fluke,” and crossing the shank close to the ring is the “stock,” which is made of two pieces of oak bound together with iron bands; sometimes it is made wholly of iron, as infig. 2, in which case it runs through a hole in the shank, and has one of its ends curved for the purpose of packing more closely and saving space (fig. 3). The anchor, when let fall from the ship, carries the cable with it, and generally falls on the crown, then tilts over so that the stock lies flat on the bottom and one of the flukes sinks in to a considerable depth by its great weight; when the ship drags at the cable it lifts up the stock and throws the whole weight of the anchor on the fluke, and makes it sink completely; any further pull must bring up a large piece of the earth before it can be moved. In “weighing” anchor, that is in pulling it up from the bottom to bring it on board again, the cable is slowly wound up by the capstan, and as the cable is shortened the ship is drawn along to a point nearly over where the anchor rests, when—the pull at the cable continuing—the shank is raised into an upright position, and the fluke and arm, instead of dragging up a great piece of earth, remove but a small portion, as may be seen by the dotted lines infigs. 4and5, which show the earth to be removed before the anchor can be drawn from its hold.Large vessels carry four anchors, the “best bower,” the “small bower,” the “sheet,” and the “spare” anchors, their size depending on the size of the ship, the rule in the Royal Navy being a hundred-weight for each gun; so that an eighty-gun ship carries anchors of four tons each, or eighty hundredweight. Anchors are made of the best and toughest wrought iron, and the greatest care is necessary in forging them in order that there may be no flaw in the welding, for a ship may be lost by an anchor breaking.

(‡ Anchor With Wood Stock.)FIG.1.(‡ Anchor With Iron Stock.)FIG.2.(‡ Space-Saving Anchor.)FIG.3.

(‡ Anchor With Wood Stock.)FIG.1.

FIG.1.

(‡ Anchor With Iron Stock.)FIG.2.

FIG.2.

(‡ Space-Saving Anchor.)FIG.3.

FIG.3.

(‡ Anchor At Rest.)FIG.4.(‡ “Weighing” Anchor.)FIG.5.

(‡ Anchor At Rest.)FIG.4.

FIG.4.

(‡ “Weighing” Anchor.)FIG.5.

FIG.5.

These ponderous instruments are used for the purpose of securing ships and other vessels, that they may not be driven onwards by the wind or tide. They are attached to a strong rope or chain, called the “cable,” and when not in use are kept swung at the fore-part or bow of a ship, the cable being wound round an apparatus called the capstan, which serves to let it out or draw it in. Anchors are made of iron, and are of the form delineated infig. 1. The straight part from the ring to the bend is called the “shank,” the curved part is made up of the two “arms,” and the centre where it joins the shank is called the “crown.” At the end of each arm is a plate of iron of triangular form, called a “fluke,” and crossing the shank close to the ring is the “stock,” which is made of two pieces of oak bound together with iron bands; sometimes it is made wholly of iron, as infig. 2, in which case it runs through a hole in the shank, and has one of its ends curved for the purpose of packing more closely and saving space (fig. 3). The anchor, when let fall from the ship, carries the cable with it, and generally falls on the crown, then tilts over so that the stock lies flat on the bottom and one of the flukes sinks in to a considerable depth by its great weight; when the ship drags at the cable it lifts up the stock and throws the whole weight of the anchor on the fluke, and makes it sink completely; any further pull must bring up a large piece of the earth before it can be moved. In “weighing” anchor, that is in pulling it up from the bottom to bring it on board again, the cable is slowly wound up by the capstan, and as the cable is shortened the ship is drawn along to a point nearly over where the anchor rests, when—the pull at the cable continuing—the shank is raised into an upright position, and the fluke and arm, instead of dragging up a great piece of earth, remove but a small portion, as may be seen by the dotted lines infigs. 4and5, which show the earth to be removed before the anchor can be drawn from its hold.

Large vessels carry four anchors, the “best bower,” the “small bower,” the “sheet,” and the “spare” anchors, their size depending on the size of the ship, the rule in the Royal Navy being a hundred-weight for each gun; so that an eighty-gun ship carries anchors of four tons each, or eighty hundredweight. Anchors are made of the best and toughest wrought iron, and the greatest care is necessary in forging them in order that there may be no flaw in the welding, for a ship may be lost by an anchor breaking.

CHAINS.(‡ Link Chain.)FIG.1.(‡ Wheel Chain.)FIG.2.(‡ Chain With Stay.)FIG.3.(‡ Chain With Extended Stay.)FIG.4.Chains are made up of separate links of rigid metal which having no flexibility in themselves are yet so united that each shall move freely on the next links to it, and thus produce a flexible whole. For ornamental purposes there is almost an endless variety of patterns, as may be seen in jewellery-work—but for the purposes of business and machinery there are chiefly but two, the ordinary, asfig. 1, and that which will only bend in one plane, as infig. 2—this is chiefly made use of in passing round wheels, as in clocks. Chains are used where rough wear is required, in which case rope would be rapidly worn through. Cables of chain are now much more generally used than hempen ones, as they are more to be depended on, take up less room, and are not so liable to be cut or worn by rough rocks at the bottom. In chain cables a “stay” is placed in every link (fig. 3), which greatly increases its strength, but the best form of chain cable is shown atfig. 4; in this the links are somewhat angular, and the stays longer. Chains are chiefly made by machinery; the rods are first drawn out of the proper size, pieces of the required length are then cut off and bent to the right form, and the stay and this link are then both made white hot, placed in their right position, and welded together by pressure.

(‡ Link Chain.)FIG.1.(‡ Wheel Chain.)FIG.2.(‡ Chain With Stay.)FIG.3.(‡ Chain With Extended Stay.)FIG.4.

(‡ Link Chain.)FIG.1.

FIG.1.

(‡ Wheel Chain.)FIG.2.

FIG.2.

(‡ Chain With Stay.)FIG.3.

FIG.3.

(‡ Chain With Extended Stay.)FIG.4.

FIG.4.

Chains are made up of separate links of rigid metal which having no flexibility in themselves are yet so united that each shall move freely on the next links to it, and thus produce a flexible whole. For ornamental purposes there is almost an endless variety of patterns, as may be seen in jewellery-work—but for the purposes of business and machinery there are chiefly but two, the ordinary, asfig. 1, and that which will only bend in one plane, as infig. 2—this is chiefly made use of in passing round wheels, as in clocks. Chains are used where rough wear is required, in which case rope would be rapidly worn through. Cables of chain are now much more generally used than hempen ones, as they are more to be depended on, take up less room, and are not so liable to be cut or worn by rough rocks at the bottom. In chain cables a “stay” is placed in every link (fig. 3), which greatly increases its strength, but the best form of chain cable is shown atfig. 4; in this the links are somewhat angular, and the stays longer. Chains are chiefly made by machinery; the rods are first drawn out of the proper size, pieces of the required length are then cut off and bent to the right form, and the stay and this link are then both made white hot, placed in their right position, and welded together by pressure.

CRANES.(‡ Yard Crane.)(‡ Wheel Assembly.)FIG.1.(‡ Floor Crane.)FIG.2.(‡ Landing Crane.)FIG.4.(‡ Landing Crane.)FIG.3.(‡ Jib Crane.)FIG.5.(‡ Swing Crane.)FIG.6.These machines are used for raising heavy bodies in a perpendicular direction. They are of various forms suitable for almost every purpose, and to most of them are adapted two or more wheels with teeth, one small and one large, for the purpose of obtaining power at the expense of time (fig. 1); the small wheel is turned by a windlass, and turns the larger one very slowly but with great power. The common warehouse or cellar crane is generally an iron frame with two pulleys, and the arrangement shown atfig. 1. which is usually inside the warehouse, while the crane is outside to raise goods from carts, &c., into the floors above (fig. 2). Cranes at the sides of canals or rivers for landing goods are sometimes made asfigs. 3and4; in the last there is a heavy stone placed to balance the weight at the end of the crane. What is called the “jib crane” is often “rigged” up on shipboard for shipping and unshipping goods (fig. 5). Cranes for very heavy purposes have been made upon the tubular principle and consist of iron plates rivetted together so as to form a hollow curved crane, similar to the hollow girders used in bridges. Where goods have to be brought from one particular spot to another, as infig. 6, the swing crane is used. Amongst cranes may be named the hydraulic lift; this is exactly similar to the hydraulic press, only applied in a different manner, and is used to lift very heavy weights but short distances, as for raising heavy goods on to railway trucks, &c.

(‡ Yard Crane.)

(‡ Wheel Assembly.)FIG.1.(‡ Floor Crane.)FIG.2.(‡ Landing Crane.)FIG.4.

(‡ Wheel Assembly.)FIG.1.

FIG.1.

(‡ Floor Crane.)FIG.2.

FIG.2.

(‡ Landing Crane.)FIG.4.

FIG.4.

(‡ Landing Crane.)FIG.3.(‡ Jib Crane.)FIG.5.(‡ Swing Crane.)FIG.6.

(‡ Landing Crane.)FIG.3.

FIG.3.

(‡ Jib Crane.)FIG.5.

FIG.5.

(‡ Swing Crane.)FIG.6.

FIG.6.

These machines are used for raising heavy bodies in a perpendicular direction. They are of various forms suitable for almost every purpose, and to most of them are adapted two or more wheels with teeth, one small and one large, for the purpose of obtaining power at the expense of time (fig. 1); the small wheel is turned by a windlass, and turns the larger one very slowly but with great power. The common warehouse or cellar crane is generally an iron frame with two pulleys, and the arrangement shown atfig. 1. which is usually inside the warehouse, while the crane is outside to raise goods from carts, &c., into the floors above (fig. 2). Cranes at the sides of canals or rivers for landing goods are sometimes made asfigs. 3and4; in the last there is a heavy stone placed to balance the weight at the end of the crane. What is called the “jib crane” is often “rigged” up on shipboard for shipping and unshipping goods (fig. 5). Cranes for very heavy purposes have been made upon the tubular principle and consist of iron plates rivetted together so as to form a hollow curved crane, similar to the hollow girders used in bridges. Where goods have to be brought from one particular spot to another, as infig. 6, the swing crane is used. Amongst cranes may be named the hydraulic lift; this is exactly similar to the hydraulic press, only applied in a different manner, and is used to lift very heavy weights but short distances, as for raising heavy goods on to railway trucks, &c.

CRANKS.(‡ Knife-Grinder.)(‡ Piston Crank.)Cranks are bends in the axle of any part of a machine by which an up-and-down motion is converted into a circular or rotatory one, as in the common knife grinder’s machine; in this arrangement a fly-wheel is necessary to continue by its momentum (tendency to go on) the motion begun by the upward and downward action of the treadle, piston-rod, &c., as the case may be. The cranks of steam-vessels are among the heaviest pieces of forging that are wrought by Nasmyth’s steam hammer, cast-iron being too brittle to be used for the purpose.

(‡ Knife-Grinder.)

(‡ Piston Crank.)

Cranks are bends in the axle of any part of a machine by which an up-and-down motion is converted into a circular or rotatory one, as in the common knife grinder’s machine; in this arrangement a fly-wheel is necessary to continue by its momentum (tendency to go on) the motion begun by the upward and downward action of the treadle, piston-rod, &c., as the case may be. The cranks of steam-vessels are among the heaviest pieces of forging that are wrought by Nasmyth’s steam hammer, cast-iron being too brittle to be used for the purpose.

FIRE-ARMS AND PROJECTILES.FIG.11. MACHINE FOR MAKING MINIÉ RIFLE BULLETS.FIG.1. MUSKET BORING.FIG.2. RIFLING PROCESS.(‡ Rifle With Bayonet.)FIG.5.In the manufacture of fire-arms the chief parts consist of the metal tube from which the projectiles are to be expelled, the stock of the musket and the carriages of great guns or cannon being only varieties of the same thing, namely a convenient platform from which to fire the tube, which is the real instrument. In the manufacture of muskets, pistols, and cheap fowling-pieces, the barrel is made from a sheet of soft iron rolled up lengthwise round a rod or “mandril,” the edges overlapping each other, which are then welded together; but in the best guns the barrels are twisted, that is, a slip or fillet of iron half-an-inch broad and of sufficient length is twisted in a spiral round the mandril, and then the whole is welded together. The barrel is “bored” by means of a square-headed drill of steel turned in a kind of lathe (fig. 1), and the interior afterwards polished with oil and emery-powder until it is perfectly bright and even; the breech is then made separately, and screwed in. The best iron for gun-barrels is called “stubb iron,” consisting of old horse-shoe nails welded together, and is very soft and even in its grain. The barrel is made red-hot and suffered to cool very slowly; this is called “annealing,” and it prevents any part being brittle, and therefore liable to burst with the charge in firing. Rifled barrels are those which have one or more grooves cut in the inside of the barrel from the muzzle to the breech in a spiral direction, each making one turn before it completes the length of the barrel (fig. 2).(‡ Percussion Cap Breech.)FIG.3.(‡ Hammer Mechanism.)FIG.4.The old “flint” lock has now quite gone out of use, having been superseded by the “percussion.” This is a contrivance to cause that part of the lock called the cock or hammer to strike the percussion cap with great force, and so discharge it (figs. 3and4). The cap is put on to a small projection called the “nipple,” which has a hole at the top communicating with the barrel, and down which the spark from the percussion cap passes.In rifled guns, of late, the use of conical balls has been introduced, for the effect of the charge in propelling a ball rapidly out of a barrel with spiral grooves is to turn it as it passes out of the barrel, and consequently to “spin” it with great velocity in one direction, like a top; the effect of this is to balance every part of the ball in the air and so cause it to take a true direction, for if the merest notch or hollow existed in a spherical ball, that part being lightest and having the least momentum would not maintain its rate so long, and by lagging behind cause the ball to describe a part of a circle in its course. It is thus that the balls from common muskets, although rightly directed, often fall extremely wide of the mark. Military muskets and rifles are fitted with bayonets, that they may act both as lances and fire-arms (fig. 5).GUN-BORING MACHINE.GUN-MOULD.“Ordnance,” or great guns are made of cast-iron or of gun-metal (a mixture of copper and tin), but experiments have lately been made with wrought-iron and cast-steel, with the view of obtaining a tougher and more durable material. They are cast solid, and afterwards bored with a machine. The following account of gun-casting at Woolwich Arsenal appeared in the “Times” of January 22, 1858:—“As the plug was drawn the glowing mass leapt out like a stream of silver, filling up the moulds for two twelve-pounder howitzers that were to be cast, and leaving a bright, hungry-looking flame playing over them, making everything red-hot which it approached. In this workshop about twenty men and boys produce twelve brass guns per week, as well as tangent-scales for ships’ guns, lock-covers, brass fittings for machinery, &c., and iron castings. Each gun cast requires two days to cool, when it is removed to the turnery to be bored; and it was to this workshop that the royal party next proceeded, and saw the guns in all their stages of trimming, finishing, and boring. Three-quarters of an hour suffice to cut a gun to its proper length and remove the rough sand which adheres to it after casting. It is then turned over to another man and another machine, and the whole of its outside shaping and marking is completely finished in two days, when it is again turned over to a fresh machine, and bored and drilled ready for service in a day-and-a-half more. With the present machinery the turnery at Woolwich could finish thirty brass guns in a week, though at this time it never completes more than ten or twelve.”(‡ Field Gun.)FIG.6.The ordinary form of “gun” is shown byfig. 6. The knob at the right-hand side of the cut is called the “button,” the next division the “vent field,” beyond this to the rim the “first reinforce,” further on, the “second reinforce,” from which a cylindrical bar projects on each side for attaching the gun to the carriage, called “trunnions.” Beyond this to the next rim is called the “chace,” and beyond this again to the end the “muzzle.” Guns are chiefly used to throw solid round shot of cast-iron, accurately turned to a sphere, and the weight of these determines the character of the gun, as a thirty-two pounder, &c., the words “heavy” and “light” designating the thickness and consequent weight of the metal composing it. There is a smaller and shorter kind of gun, called a “carronade,” which is held to the carriage by a projection underneath, having a hole for a bolt to secure it, instead of trunnions. Another kind of gun, called a “howitzer,” is of shorter proportions than the ordinary gun and larger in the bore; it is chiefly intended to throw shells at a slight elevation. The mortar is still shorter, and of much thicker metal; it is held to a sort of platform by trunnions at its extreme end, and is intended to throw shells to great distances, and at a great elevation.BULLET-CASTING, WOOLWICH ARSENAL.FIG.7. SHELL CASTING.(‡ Nippers.)FIG.10.PREPARING LEAD FOR BULLETS.(‡ Bullet Mould.)FIG.8.(‡ Bullets.)FIG.9.The sizes of howitzers and mortars are expressed by the diameter of the shell they are intended to throw; the largest of which at present in general use is the “thirteen-inch.” This immense shell when charged weighs nearly 200 pounds. These shells or “bombs” as they were formerly called, are cast hollow (fig. 7), with a small opening into which a “fuze” or wooden tube filled with combustible matter is inserted; they are charged with gunpowder, which on being ignited by the fuze burning down to it, explodes and bursts the shell into fragments, which fly about with terrible force. What are called “shrapnel-shells,” are those shells which are filled with both gunpowder and leaden bullets, to be scattered about by the explosion. Case-shot is a name given to a packet of bullets inclosed in a tin canister and used as a projectile, the case bursts and the bullets are scattered. Grape-shot is the name given to a collection of nine iron balls packed up so as to be used as one. Hand-grenades are small shells of about three pounds’ weight, to be cast by hand. Bullets for the ordinary musket are simple balls of lead, in some cases cast six at a time in moulds (fig. 8), and coming out in one piece as seen atfig. 9, which are afterwards separated and finished off by a sort of nippers as seen infig. 10; but for the most part musket and rifle bullets are formed by compression. The bullets for the Minié rifle are made by machinery; they are of a conical form, with a hollow at the base into which a small plug of box wood is fitted, this end being towards the powder receives the whole force of the explosion, the effect of which is to drive in the plug and open out the bullet, thus fitting it tightly into the grooves of the rifle and preventing any loss of power by the escape of the gases resulting from the combustion of the powder. The machine for making these bullets is shown atfig. 11. The following is an account of it, taken from the “Times”:—“Like all the machines here, these are perfectly automatic. Coils of solid leaden piping are hung in it, which it unwinds, cuts to the required length, stamps with steel dies into the form of a Minié bullet, and then conveys away into boxes. Each machine has four dies, which cut, stamp, and pass into boxes thirty-six bullets per minute, giving for each machine an average of 7,000 per hour. There are four of such machines, which thus each day turn out 300,000 Minié bullets; but, of course, as they never tire, the number produced can at any time be doubled by leaving them to work all night. They are so simple in their construction that one man could easily attend to them all. It was a curious contrast to the silent rapidity with which these deadly messengers were formed, to watch a number of men and boys working near them casting round musket-balls for Shrapnel shells, in the old style of hand work. By this method two persons can only rough-cast seven cwt. of bullets per day, or about 12,500, which it takes two persons another day to trim. Thus, four hands, with a great consumption of fuel to keep the lead always melted can only produce 6,000 bullets per day or 1,000 less than each machine produces in one hour.”The machines for making the box wood plugs are also described:—“Each of these was managed by a child, who kept it properly fed with small sticks of box, which the machine converted into plugs at the rate of 15,000 in nine hours, or nearly 300,000 per day for them all.”Rockets, as used for projectiles, are similar to those in ordinary use, but that they have iron cases and are made to start from an iron tube, down which the stick passes, and which directs the course of their flight. They are made of various weights, the largest being thirty-two pounds. These enormous rockets pass to a very great distance and are made either to explode like shells, or burn fiercely for several minutes, like what are called “carcases,” thus setting fire to houses, &c., against which they may be directed; but hitherto their course has been but little under control, and therefore not much to be depended on. They cause great confusion in masses of troops, when directed against them.

FIG.11. MACHINE FOR MAKING MINIÉ RIFLE BULLETS.

FIG.1. MUSKET BORING.FIG.2. RIFLING PROCESS.

FIG.1. MUSKET BORING.

FIG.2. RIFLING PROCESS.

(‡ Rifle With Bayonet.)FIG.5.

FIG.5.

In the manufacture of fire-arms the chief parts consist of the metal tube from which the projectiles are to be expelled, the stock of the musket and the carriages of great guns or cannon being only varieties of the same thing, namely a convenient platform from which to fire the tube, which is the real instrument. In the manufacture of muskets, pistols, and cheap fowling-pieces, the barrel is made from a sheet of soft iron rolled up lengthwise round a rod or “mandril,” the edges overlapping each other, which are then welded together; but in the best guns the barrels are twisted, that is, a slip or fillet of iron half-an-inch broad and of sufficient length is twisted in a spiral round the mandril, and then the whole is welded together. The barrel is “bored” by means of a square-headed drill of steel turned in a kind of lathe (fig. 1), and the interior afterwards polished with oil and emery-powder until it is perfectly bright and even; the breech is then made separately, and screwed in. The best iron for gun-barrels is called “stubb iron,” consisting of old horse-shoe nails welded together, and is very soft and even in its grain. The barrel is made red-hot and suffered to cool very slowly; this is called “annealing,” and it prevents any part being brittle, and therefore liable to burst with the charge in firing. Rifled barrels are those which have one or more grooves cut in the inside of the barrel from the muzzle to the breech in a spiral direction, each making one turn before it completes the length of the barrel (fig. 2).

(‡ Percussion Cap Breech.)FIG.3.(‡ Hammer Mechanism.)FIG.4.

(‡ Percussion Cap Breech.)FIG.3.

FIG.3.

(‡ Hammer Mechanism.)FIG.4.

FIG.4.

The old “flint” lock has now quite gone out of use, having been superseded by the “percussion.” This is a contrivance to cause that part of the lock called the cock or hammer to strike the percussion cap with great force, and so discharge it (figs. 3and4). The cap is put on to a small projection called the “nipple,” which has a hole at the top communicating with the barrel, and down which the spark from the percussion cap passes.

In rifled guns, of late, the use of conical balls has been introduced, for the effect of the charge in propelling a ball rapidly out of a barrel with spiral grooves is to turn it as it passes out of the barrel, and consequently to “spin” it with great velocity in one direction, like a top; the effect of this is to balance every part of the ball in the air and so cause it to take a true direction, for if the merest notch or hollow existed in a spherical ball, that part being lightest and having the least momentum would not maintain its rate so long, and by lagging behind cause the ball to describe a part of a circle in its course. It is thus that the balls from common muskets, although rightly directed, often fall extremely wide of the mark. Military muskets and rifles are fitted with bayonets, that they may act both as lances and fire-arms (fig. 5).

GUN-BORING MACHINE.

GUN-MOULD.

“Ordnance,” or great guns are made of cast-iron or of gun-metal (a mixture of copper and tin), but experiments have lately been made with wrought-iron and cast-steel, with the view of obtaining a tougher and more durable material. They are cast solid, and afterwards bored with a machine. The following account of gun-casting at Woolwich Arsenal appeared in the “Times” of January 22, 1858:—“As the plug was drawn the glowing mass leapt out like a stream of silver, filling up the moulds for two twelve-pounder howitzers that were to be cast, and leaving a bright, hungry-looking flame playing over them, making everything red-hot which it approached. In this workshop about twenty men and boys produce twelve brass guns per week, as well as tangent-scales for ships’ guns, lock-covers, brass fittings for machinery, &c., and iron castings. Each gun cast requires two days to cool, when it is removed to the turnery to be bored; and it was to this workshop that the royal party next proceeded, and saw the guns in all their stages of trimming, finishing, and boring. Three-quarters of an hour suffice to cut a gun to its proper length and remove the rough sand which adheres to it after casting. It is then turned over to another man and another machine, and the whole of its outside shaping and marking is completely finished in two days, when it is again turned over to a fresh machine, and bored and drilled ready for service in a day-and-a-half more. With the present machinery the turnery at Woolwich could finish thirty brass guns in a week, though at this time it never completes more than ten or twelve.”

(‡ Field Gun.)FIG.6.

FIG.6.

The ordinary form of “gun” is shown byfig. 6. The knob at the right-hand side of the cut is called the “button,” the next division the “vent field,” beyond this to the rim the “first reinforce,” further on, the “second reinforce,” from which a cylindrical bar projects on each side for attaching the gun to the carriage, called “trunnions.” Beyond this to the next rim is called the “chace,” and beyond this again to the end the “muzzle.” Guns are chiefly used to throw solid round shot of cast-iron, accurately turned to a sphere, and the weight of these determines the character of the gun, as a thirty-two pounder, &c., the words “heavy” and “light” designating the thickness and consequent weight of the metal composing it. There is a smaller and shorter kind of gun, called a “carronade,” which is held to the carriage by a projection underneath, having a hole for a bolt to secure it, instead of trunnions. Another kind of gun, called a “howitzer,” is of shorter proportions than the ordinary gun and larger in the bore; it is chiefly intended to throw shells at a slight elevation. The mortar is still shorter, and of much thicker metal; it is held to a sort of platform by trunnions at its extreme end, and is intended to throw shells to great distances, and at a great elevation.

BULLET-CASTING, WOOLWICH ARSENAL.FIG.7. SHELL CASTING.(‡ Nippers.)FIG.10.PREPARING LEAD FOR BULLETS.

BULLET-CASTING, WOOLWICH ARSENAL.

FIG.7. SHELL CASTING.

(‡ Nippers.)FIG.10.

FIG.10.

PREPARING LEAD FOR BULLETS.

(‡ Bullet Mould.)FIG.8.(‡ Bullets.)FIG.9.

(‡ Bullet Mould.)FIG.8.

FIG.8.

(‡ Bullets.)FIG.9.

FIG.9.

The sizes of howitzers and mortars are expressed by the diameter of the shell they are intended to throw; the largest of which at present in general use is the “thirteen-inch.” This immense shell when charged weighs nearly 200 pounds. These shells or “bombs” as they were formerly called, are cast hollow (fig. 7), with a small opening into which a “fuze” or wooden tube filled with combustible matter is inserted; they are charged with gunpowder, which on being ignited by the fuze burning down to it, explodes and bursts the shell into fragments, which fly about with terrible force. What are called “shrapnel-shells,” are those shells which are filled with both gunpowder and leaden bullets, to be scattered about by the explosion. Case-shot is a name given to a packet of bullets inclosed in a tin canister and used as a projectile, the case bursts and the bullets are scattered. Grape-shot is the name given to a collection of nine iron balls packed up so as to be used as one. Hand-grenades are small shells of about three pounds’ weight, to be cast by hand. Bullets for the ordinary musket are simple balls of lead, in some cases cast six at a time in moulds (fig. 8), and coming out in one piece as seen atfig. 9, which are afterwards separated and finished off by a sort of nippers as seen infig. 10; but for the most part musket and rifle bullets are formed by compression. The bullets for the Minié rifle are made by machinery; they are of a conical form, with a hollow at the base into which a small plug of box wood is fitted, this end being towards the powder receives the whole force of the explosion, the effect of which is to drive in the plug and open out the bullet, thus fitting it tightly into the grooves of the rifle and preventing any loss of power by the escape of the gases resulting from the combustion of the powder. The machine for making these bullets is shown atfig. 11. The following is an account of it, taken from the “Times”:—

“Like all the machines here, these are perfectly automatic. Coils of solid leaden piping are hung in it, which it unwinds, cuts to the required length, stamps with steel dies into the form of a Minié bullet, and then conveys away into boxes. Each machine has four dies, which cut, stamp, and pass into boxes thirty-six bullets per minute, giving for each machine an average of 7,000 per hour. There are four of such machines, which thus each day turn out 300,000 Minié bullets; but, of course, as they never tire, the number produced can at any time be doubled by leaving them to work all night. They are so simple in their construction that one man could easily attend to them all. It was a curious contrast to the silent rapidity with which these deadly messengers were formed, to watch a number of men and boys working near them casting round musket-balls for Shrapnel shells, in the old style of hand work. By this method two persons can only rough-cast seven cwt. of bullets per day, or about 12,500, which it takes two persons another day to trim. Thus, four hands, with a great consumption of fuel to keep the lead always melted can only produce 6,000 bullets per day or 1,000 less than each machine produces in one hour.”

The machines for making the box wood plugs are also described:—

“Each of these was managed by a child, who kept it properly fed with small sticks of box, which the machine converted into plugs at the rate of 15,000 in nine hours, or nearly 300,000 per day for them all.”

Rockets, as used for projectiles, are similar to those in ordinary use, but that they have iron cases and are made to start from an iron tube, down which the stick passes, and which directs the course of their flight. They are made of various weights, the largest being thirty-two pounds. These enormous rockets pass to a very great distance and are made either to explode like shells, or burn fiercely for several minutes, like what are called “carcases,” thus setting fire to houses, &c., against which they may be directed; but hitherto their course has been but little under control, and therefore not much to be depended on. They cause great confusion in masses of troops, when directed against them.

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