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THE PHOTOGRAPHIC NEWS. 227 much at a logs to if he looked for ... ... ..... .u.. the furnaces of the English works. The Belgians discard the costly brick-built “cones,” and construct their furnaces in barn-like buildings, roofed with tiles, and through the ridge a yard or two of what resembles nothing more than the top of a Thames steam-boat smoke-stack protrudes. This is shown in our sketch with the familiar curl of smoke issuing therefrom. Below this the draught and smoke are confined in sheet iron plates instead of the expensive brick “cone” of the English system. The ground line is gene rally about three feet above the level of the surrounding surface of terra-firma, and thereby reduces the depth necessary for the floor of the “cave.” The cave, there fore, is frequently on a level with the roadway passing the works, so that the ashes and rubbish can easily be wheeled out. The arch of the cave is generally of brick or stone, and the foundations of the furnace rest or abut thereon, as shown. Above the ground-line the work has to be very good, accurate, and substantial; fire-bricks, slabs, blocks, and lumps of various forms enter into the structure of the furnace, the whole being put together with a grout or cement of thin fire-clay, and the utmost care and highest skill in the brick-setter’s art are brought into play so as to form a firm, compact, and durable structure. The turning of the arch or furnace crown especially calls for the great est skill, for it is very much flattened on the top, and is by no means part of a regular circle or sphere, and holes have to be left in the sides opposite each pot, through which the pots are filled, and the molten glass gathered and blown. Had space permitted, we should have shown an elevation and plan of this furnace, and we could then have shown how the pots are set opposite each working hole, also the other openings into the furnace through which the pots are introduced, and through which the fuel is fed ; but our section will give so good an idea of the general arrange ment, that it will suffice for any furnace of four, six, or eight pots, and we have now merely to follow the direction of the draught, to comprehend the functions of the furnace. Cold air enters the “cave” or “tunnel,” thence, through the bars or grid, passing through the fuel, which is dis posed in a certain manner, according to the nature and quality of the coal used ; the fuel enters into vivid com bustion, and volumes of flame dart upwards towards the crown of the furnace : they also lick round the sides of the pots, in between them, and the drawing will now show how the flame is drawn down again across the surface of the pots, and darts out in a thick bundle through the working holes shown where the iron door is figured. Whilst “ founding," these doors are closed, so that the flame and smoke rush off up the conical case above the crown, and thence up the smoke-stack into the air. It will thus be seen that the pots are always in an atmo sphere of flame or intensely heated gas; no cool air should reach them, not even on the surface, for we have seen how simply but beautifully scientifically the heat is reverber ated and drawn down on to the surface of the metal in the pots. It is a grand sight to stand on the platform on which the gatherers and blowers work, shown at the top of the steps in our sketch, and when the metal is nearly fined and the iron doors are opened, and all smoke has gone, and the fuel, and the pots, and the molten glass, and the crown and walls of the interior of the furnace are one vivid white glow, the furnace is being let back a little in order that the metal may become quite fine, and lambent tongues of colourless flame dart out of the “ hole,” through which we can see right across through the heated atmo sphere of the furnace to the hole opposite. One cannot help feeling impressed with the great skill and ingenuity of man, how he tames the greatest forces, and trains the fiercest powers to conform to his will. It is a matter of regret to think that so much skill is brought to bear to produce an article which is not unfrequently sold for the ridiculous sum of one penny per superficial foot! comprehend where the glass-works were, When a furnace is constructed or rebuilt, it remains several weeks unused, so as to dry as thoroughly as it will under the normal conditions of the atmosphere. Then, if the furnace is to be kindled, a small fire is made on the bars where the word “fuel” is seen in our sketch. All openings are left full open, so that a stream of warm air circulates everywhere, and this goes on for a week or so. Simultaneously with the kindling of the furnace, a ready and matured pot is brought out of stock and carried to the pot arch. Now the pot arch is another separate and distinct small furnace, built like a small coal cellar, in one corner of which a fire is made; a pot is brought and wheeled in, and the doorway bricked up ; the heat is raised and continued until the pot becomes red hot, and then white hot, and this process goes on whilst the glass furnace is also being got into heat. At the end of a week or so the heat is increased in both furnaces, so that the rise in temperature is gradual, and the large furnace is ready to receive the pot or pots. The operation of setting pots is a difficult and remarkable one. When all is ready, the opening into the pot arch is pulled out, and the like opera tion is effected at the glass furnace; then a gang of labourers proceed to lift the white hot pot from out ot the pot arch by means of a gigantic iron pitchfork, somewhat appropriately called the “ devil,” which runs on a pair of wheels. The men push the prongs of the fork so as to encircle the pot, and weighing down the cool end they run the pot away to the furnace and thrust it on to its seat, called the “ siege,” just as shown in our sketch. Each pot has to be adjusted opposite its proper working hole, set fair and square, an equal space between each, and the greatest care observed to guard against any accident to the pots or the furnace, either by rough usage or injudicious exposure to cold air. The operation of setting eight or ten pots in a furnace is one demanding a high degree of skill on the part of the manager and his subordinates, and calls for coolness and nerve under circumstances of very trying character, for the temperature of the house becomes very high ; to anyone unaccustomed, the glare and heat are simply unbearable. The men have to be protected with woollen clothes, leather gloves, and face masks, and under stand that they have to obey instantly the commands of the manager or foreman who directs the work. When the pots are “ set,” the openings into the furnace are bricked up and otherwise closed, and the heat got up again for a few hours, for of course the heat must have declined considerably during the setting of the pots. Meanwhile the mixtures to be melted are being wheeled from the mixing room to the furnace, and placed in iron boxes or tanks, or stand in the iron wheelbarrows ready to be shovelled into the pots. INVENTORS AND DISCOVERERS. Inventors and discoverers are well known to be an injured race. Few have their rights properly recognised, and fewer still derive any personal benefit from them. It has been so from the beginning of history, and is likely to be so to the end. The introduction of photography—that is, of practi cal photography—furnishes us with a very good instance. Daguerre was hailed for some time as the one and only in ventor of practical photography. Arago, who stood sponsor for the new invention, and published it to the world in an impassioned harangue which has since become histori cal, never once mentioned the name of Nicephore Niepce, Daguerre’s dead partner, and it was not until some months afterwards that the connection between the two men got bruited abroad. To an Englishman, indeed, Mr. Bauer, the secretary of the Royal Society, was due the first signifi cant protest against ignoring Niepce’s name in connection with the discovery, for it was his impartial testimony, together with the exhibition of some of Niepce’s camera