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J. Shury Sc.

London Published by Thomas Tegg,73, Cheapside Feb 11828.

in the Russian church. The priest who administers baptism, is enjoined to blow thrice on the child's face, making the sign of the cross and pronouncing the words, exi ab eo Satan.

BLOWING, in gardening, the action of flowers, whereby they open and display their leaves. The regular blowing season is in the spring; though some plants have other extraordinary times and manners of blowing, as the Glastonbury thorn. Some flowers also, as the tulip, close every evening, and blow again in the morning. Annual plants blow sooner or later, as their seeds are put into the ground; whence the curious in gardening sow some every month in summer, and have a constant succession of flowers. The blowing of roses may be retarded by shearing of the buds as they expand.

BLOWING OF FIRE-ARMS, is when the vent er touch-hole is run or gullied, and becomes wide, so that the powder will flame out.

BLOWING OF GLASS, one of the methods of forming various kinds of works in the glass manufacture. It is performed by dipping the point of an iron blowing-pipe into melted glass, and blowing through it with the mouth, according to the circumstances of the glass to be blown. See GLASS.

BLOWING OF TIN, denotes the melting of its ore, after being first burnt, to destroy its mundic.

BLOWING MACHINES, in the arts and manufactures, are improved bellows or instruments for producing the strongest continued current of air, for a given purpose, or for facilitating the combustion of fuel, and the production of heat. For the common bellows which bears the greatest resemblance to lungs, see BELLOWS. It was a very early contrivance for artificial blowing. The blast, however, in this machine, is not continuous, but in puffs; or at intervals of time required for the air to enter through the valve; the blowing interval being as the areas of the apertures to the filling interval. This was for some time attempted to be remedied by employing two bellows which blew alternately, the blowing of one taking place while the other was filling. To this succeeded the invention of what are called double bellows, which was a valuable acquisition in the art of blowing. We have only to take a third board exactly of the shape of the two belonging to the single bellows, and connect it with the lower board by a piece of leather similar to that of the single bellows, making two cavities exactly similar, and separated by the lower board of the single bellows, which now becomes the middle board of the double. The third board we shall now call the lower board. This latter has a valve in it exactly similar to the first, which still retains its place in the new construction. The middle board is now fixed in a horizontal position, the pipe being placed to the fire to be blown. The lower board is held down by a weight, which keeps the lower cavity constantly full of air, and the top board has a weight laid upon it which presses all the air out of the upper cavity through the pipe. The requisite action by which the blowing is performed, is, first, to lift up the lower board. This forces the air from the lower into the upper cavity, the valve in the middle

board preventing its return. The weight on the upper board now presses the air with a uniform blast through the pipe. During this time the lower board descends, which fills the lower cavity with air from the atmosphere. This again rises, and gives its contents to the upper cavity, and thence through the nose-pipe. Hence we see that irregular puffing blast, which belongs to the single bellows, is here confined to the lower board only, which supplies air to the upper cavity, while the upper board is constantly pressing uniformly upon the air in it. But this does not completely obviate the irregularity of the blast. So long as the lower board is not in action, the pressure of the upper board being uniform, the blast is the same. Every time, however, the bottom board rises to force the air into the upper cavity, an extra pressure is given to the air in the upper cavity, and a temporary puff is produced. In the application of bellows to the smith's forge, the continued blast was of less importance than in the blast-furnaces applied to the smelting or refining of ores. The single bellows are at present almost exclusively employed by anchor-smiths and cutlers, while the blacksmith and most others use double bellows, which are doubtless better.

In France and on the Continent, where bellows have been wholly formed of wood, instead of the flexible sides of leather, they consist of two boxes, each open on one side, and the one being just capable of containing the other. The outer box being placed with the mouth upwards, the other is made to descend into it, with the mouth downwards; the latter being capable of moving up and down, while the other remained fixed. In the bottom of the fixed box is a valve like the common bellows, and a pipe on the same level, to let out the blast. The change of capacity, by the motion of this box, causes the blast, and with less waste of power than that occasioned by the bending of the leather in the common bellows.

A machine of this kind appears in our plate BLOWING MACHINES, figs. 1, 2, 3. ABC PEF, fig. 1, is a wooden box, which has its top and two sides flat or straight, and the end, BA E, formed into an arched or cylindrical surface, of which the line F P at the other end is the axis. This box is open below, and receives within it the shallow box K HG M, &c. fig. 2, which exactly fills it. The line F P of the one coincides with FP of the other, and along these lines is a set of hinges, on which the upper box turns as it rises and sinks; the lower box is made fast to a frame sunk in the ground. A pipe or tube, QQ, proceeds from the end of it and terminates at the furnace, where it ends in a small pipe called a tuyere. This lower box is open above, and has in its bottom two large valves, VV, opening inwards. The conducting pipe is also sometimes furnished with a valve opening outwards, to prevent burning coals from being sucked into the bellows when the upper box is drawn up. The joint along PF is made tight by thin leather nailed along it. The sides and ends of the fixed box are made to fit the sides and curved end of the upper box, so that this last can be raised and lowered round the joint

FP without sensible friction; and yet without suffering much air to escape; but as this would not be sufficiently air tight, by reason of the shrinking and warping of the wood, a farther contrivance is had recourse to. A slender lath of wood divided into several joints, and covered on the outer edge by soft leather, is laid along the upper edges of the sides and ends of the lower box. This lath is so broad that, when its inner edge is even with the inside of the box, its outer edge projects about an inch. It is kept in this position by a number of steel wires, which are driven into the bottom of the box and stand up touching the sides. By these means the laths are pressed close to the sides, and curved end of the movable box, and the spring wires yield to all their inequalities. A bar of wood, RS, is fixed to the upper board, by which it is either raised by machinery, to sink again by its own weight (having an additional load laid on it), or it is forced down by a crank or wiper of the machinery, and afterwards raised by the same. The operation here is precisely the same as in the common household bellows. When the board is lifted up, the air enters by the valves VV, fig. 3, and is afterwards expelled at the pipe QQ. These machines, used in the larger metallurgic operations of mining countries, and throughout the continent, are sometimes of very great size, and are made capable of expelling ninety cubic feet of air at one stroke, repeated eight times in a minute.

English blowing machines have been chiefly improved by means of a piston and cylinder, the latter commonly of iron, but sometimes composed of wood on the plan of coopers' work. The piston is surrounded with a broad strap of thick soft leather, and stuffed similarly to that of the steam engine. The cylinder is furnished with one or more large valves in the side or bottom, by which the air enters when the piston is drawn upwards, and is expelled of course when it goes down: this action driving it along a large pipe which terminates in a small orifice connected with the furnace, and sometimes with a wind cellar or reservoir of air, which supplies forges, &c. by means of a cock. The piston in these cases is raised by water or other works; and sometimes two or more are working at a time to ensure a uniform blast.

The blowing machine of Chastillion consists of two cylinders, A, B, fig. 4, loaded with weights, which are suspended from the two extremities of a lever, or beam, moving about a central fulcrum E. From the top of each there is a large flexible pipe, which are both united in H, whence a pipe HT leads to the tuyere. There are valves at G and H opening upwards, into the flexible pipes; and other valves, L, M, adjoining to them, in the top of each cylinder, opening inwards, but kept shut by a slight spring. Motion is given to the lever by a machine, which may of course have water, wind, or steam, for its impelling agent. The operation of this engine is evident: when the cylinder A is descending, the water entering at its bottom compresses the air, and forces it along the pipe FH KT. In the mean time the cylinder B is rising, the air finding an entrance through the valve M having reached the top, it begins to descend, and the other to ascend, and thus the

An

blast is rendered nearly continuous, but certainly not so equable as is desirable in most cases. improvement upon this construction has been introduced at the Patent Iron Cable Manufactory of Messrs. Brunton and Co. Commercial Road; where, instead of the flexible pipe KHT, a pipe is standing up a little above the surface of the water under each cylinder; through which the air is made to pass by the compression caused by the descent of each cylinder; the air also passing into a general reservoir or wind chest, is kept constantly under a given pressure and led to any required point. The lever to which the cylinders are suspended, is attached immediately to the beam of a small steam engine applied wholly to this purpose, and thus the utmost uniformity of action is secured. Each of these is, in fact, a species of hydraulic bellows. The extensive use of coal in smelting iron, first rendered it necessary in this country to construct durable machines, capable of affording a powerful and constant blast. The first cylinders of magnitude used as blowing machines were erected by Mr. John Smeaton, in 1760, at the Carron Iron Works. The pumps were wrought alternately by a water wheel, having four cranks upon its axis, each of which moved the piston of a cylinder, which had a stroke of four feet six inches; the diameter of each cylinder being also four feet six inches. Where a fall of water could not be obtained, steam engines were employed to work the pumps. A water regulator has been introduced of late years, connected with a double acting blowing cylinder, wrought by a steam engine.

A machine of this kind, of large dimensions, is represented in fig. 5. It is wrought by a steam engine of thirty-five horse power, with a steam cylinder of thirty-three inches diameter, acting with a seven feet stroke. On the opposite end of the beam from the steam cylinder is jointed the rod D, which is turned exceedingly true, so as to move through the stuffing box without allowing any air to escape, and without any unnecessary friction. A quantity of hemp is placed round the rod in the box a a, which forms part of the lid of the cylinder, and is held tight by the iron nuts b, b. The piston is fitted to the lower end of the rod D, and is packed with leather so as to fill exactly the internal diameter of the cylinder A A. To this cylinder are fixed four necks, B, F, G, H; two of which, B, F, contain the suction valves, by which the air enters the cylinder, while the other two contain the forcing valves, through which the air is expelled at every elevation and depression of the piston into the chambers I, K, and through the pipes L, M, into the regulating receiver OP, which is of the form of a parallelopipedon, or an inverted box without the lid, and is immersed in a cistern RS, filled with water. Let us suppose that the piston is at the bottom of the cylinder AA, and begins to be raised by the engine. The air above the piston will obviously be condensed, and forcing open the hanging valves in the neck G, will rush through them into the pipe L, and thence into the receiver OP. While the piston thus rises and condenses the air above it, there is a vacuum below the piston, and the external air rushes through the valves in the neck F, and fills the space below the piston. When the piston descends

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