Bellows, an instrument contrived for propelling air through a pipe, employed for blowing fires, supplying air to ventilate mines, filling the pipes of an organ with wind, and other purposes. The use of this apparatus may be traced back to a very early period. It is spoken of by Jeremiah (vi. 29), and alluded to by Eze-kiel (xxii. 20). When Homer describes the forging of the iron shield of Achilles, he speaks of the furnace into which the materials were thrown being blown by 20 pairs of bellows From the remarks of Plautus in his Frarjmenta, and of Virgil in the Georgics, it would appear that the bellows of the ancients were made wholly of leather. The first account we have of wooden bellows is by Henry bishop of Bamberg, in 1620, when one named Pfannenschmidt (bellows smith) commenced the manufacture of them in the Hartz forest, and by his success excited the jealousy of those of the same trade in the place. His art was disclosed only to his son, and the monopoly of the forest remained in the hands of his descendants to this century. Hans Losinger, an organist of Nuremberg, is by some supposed to have invented the wooden bellows in 1550. Among many primitive nations of Asia and Africa this machine is still employed in its simplest form for blowing by hand the fires of rudely constructed furnaces, probably of the same form as those in use in the times of Homer and of the Jewish prophets. - As ordinarily constructed, the instrument consists of two similar plates of wood connected by a strip of leather fastened around their edges, which with the plates completely encloses a chamber for air, and is so made that the plates may be made to approach and recede by folding and unfolding the leather.
In the lower plate is fixed a valve opening inward, through which the air enters as the plates are separated, and which closes as they are brought together, forcing the air to seek some other outlet. This is provided in a tube of small area compared to that of the valve, so that the air is made to rush outward with great velocity. As the action of this machine is to give an intermittent blast, it has been improved by introducing a third plate, attached to the lower one as this was to the upper, thus making a double bellows.. The two lower plates have valves opening upward, and the pipe or nozzle for the exit of the air is in the upper of the two chambers. The middle plate is worked up and down by a lever arm, and weights are placed upon the top of the bellows to force out the air continuously, and others are suspended from the bottom board to keep the lower chamber distended with air. A circular form is sometimes given to the plates or boards, and the air chamber surrounded by the leather is cylindrical. When shut together it is very compact and portable, which renders it a convenient form for portable forges. The inhabitants of Hindostan make use of such bellows for blowing their small iron furnaces.
A man sits down between two of them, and with one hand upon each works them alternately up and down, producing a tolerably continuous blast, but of small capacity and force. - The bellows used by the Chinese is a simple contrivance for forcing air with any desired pressure, and is upon the same principle with the large blowing machines now in general use. It is a square wooden box or pipe, with a piston rod working in one end, and carrying a closely fitting piston, by the movement of which the air is pushed through a smaller pipe in the other end. On the reverse motion the air enters through valves and refills the box. - Bellows are used for obtaining a very hot flame with illuminating gas. The blast of air is directed through the centre of the yellow gas flame, which immediately assumes a pale blue color and a long pointed form. By losing its illuminating power the available heat is very much increased. Such a flame is made use of by the chemist in trying experiments which require an intense heat on a small scale, and by the glass blower in making the melted glass assume the desired form. A very good form of .bellows for the glass blower, which until recently was only made in Paris, is now manufactured in this country.
It consists essentially of a cylinder 8 inches in diameter and 14 inches high, made of leather or india rubber, which has three horizontal wooden disks or diaphragms, one at the top, one a little below the middle, and one at the bottom; thus dividing the cylinder into two compartments, of which the lower one is the force pump, while the upper is the reservoir which retains the air and equalizes the blast. The details are as follows: The middle disk alone is fixed permanently to the glass Mower's table. In the lower disk a check valve is placed, which allows the air to enter but Dot to leave the lower compartment.
The centre disk has a valve similarly arranged, with reference to the upper compartment. The lower disk can be forced upward by means of a lever connected with a treadle, thereby forcing the contained air into the upper compartment. The upper disk is continually pressed downward by a spiral spring which compresses the enclosed air, and yields in consequence a steady and powerful blast through a tube which for convenience is placed on the upper surface of the middle disk. - The useful effect of the bellows is in exciting combustion, by furnishing a continuous stream of oxygen in the fresh supplies of air, and in removing by the force of the blast those products of combustion which ordinarily exclude the approach of the air and impede the continuation of the process. Its power of rapidly exciting vivid combustion and intense heat is well seen in the action of the smith's bellows in common use. Excepting for some small operations for metallurgic purposes, and for other objects not requiring either a large volume or great pressure of air, the ancient bellows is now for the most part replaced by more efficient apparatus, as the so-called blowing machines and fan-blowers, descriptions of which will be found under Blowing Ma-chinks.