| Fig. 9.—Steam-jet Blower. |
In the jet blower (fig. 9) a jet of steam is used to induce a current of air. Into one end of a trumpet-shaped pipe B projects a steam pipe A. This steam pipe terminates in a small opening, say, one-eighth of an inch, through which the steam is allowed to flow freely. The effect is to cause a movement of the air in the pipe, with the result that a fresh supply is drawn in through the annular opening at C, C, and a continuous stream of air passes along the pipe. This is the form of blower made by Messrs Meldrum Bros. of Manchester, and is largely used for delivering air under the fire bars of boiler and other furnaces. In some cases the jets of steam are allowed to enter a boiler furnace above the fire, thus inducing a current of air which helps the chimney draught and is often used to do away with the production of smoke; they are also used for producing currents of air for purposes other than those of boiler fires, and are very convenient where considerable quantities of air are wanted at very low pressures and where the presence of the moisture of the steam does not matter.
Sometimes jets of high-pressure air flowing at great velocities are used to induce more slowly-moving currents of larger volumes of air at low pressures.
(W. C. P.)
[1] The Old English word for this appliance was blástbaelig, i.e. “blow-bag,” cf. German Blasebalg. By the 11th century the first part of the word apparently dropped out of use, and baelig, bylig, bag, is found in early glossaries as the equivalent of the Latin follis. Baelig became in Middle English bely, i.e. “belly,” a sack or bag, and so the general word for the lower part of the trunk in man and animals, the stomach, and another form, probably northern in origin, belu, belw, became the regular word for the appliance, the plural “bellies” being still used till the 16th century, when “bellows” appears, and the word in the singular ceases to be used. The verb “to bellow” of the roar of a bull, or the low of a cow, is from Old English bellan, to bell, roar.
BELLOY, DORMONT DE, the name assumed by Pierre Laurext Buireite (1727-1775), French dramatist, was born at Saint-Flour, in Auvergne, on the 17th of November 1727. He was educated by his uncle, a distinguished advocate in Paris, for the bar. To escape from a profession he disliked he joined a troupe of comedians playing in the courts of the northern sovereigns. In 1758 the performance of his Titus, which had already been produced in St Petersburg, was postponed through his uncle’s exertions; and when it did appear, a hostile cabal procured its failure, and it was not until after his guardian’s death that de Belloy returned to Paris with Zelmire (1762), a fantastic drama which met with great success. This was followed in 1765 by the patriotic play, Le Siège de Calais. The moment was opportune. The humiliations undergone by France in the Seven Years’ War assured a good reception for a play in which the devotion of Frenchmen redeemed disaster. The popular enthusiasm was unaffected by the judgment of calmer critics such as Diderot and Voltaire, who pointed out that the glorification of France was not best effected by a picture of defeat. De Belloy was admitted to the Academy in 1772. His attempt to introduce national subjects into French drama deserves honour, but it must be confessed that his resources proved unequal to the task. The Siège de Calais was followed by Gaston et Bayard (1771), Pedro le cruel (1772) and Gabrielle de Vergy (1777). None of these attained the success of the earlier play, and de Belloy’s death, which took place on the 5th of March 1775, is said to have been hastened by disappointment.
BELL or INCHCAPE ROCK, a sandstone reef in the North Sea, 11 m. S.E. of Arbroath, belonging to Forfarshire, Scotland. It measures 2000 ft. in length, is under water at high tide, but at low tide is exposed for a few feet, the sea for a distance of 100 yds. around being then only three fathoms deep. Lying in the fairway of vessels making or leaving the Tay and Forth, besides ports farther north, it was a constant menace to navigation. In the great gale of 1799 seventy sail, including the “York,” 74 guns, were wrecked off the reef, and this disaster compelled the authorities to take steps to protect shipping. Next year Robert Stevenson modelled a tower and reported that its erection was feasible, but it was only in 1806 that parliamentary powers were obtained, and operations began in August 1807. Though John Rennie had meanwhile been associated with Stevenson as consulting engineer, the structure in design and details is wholly Stevenson’s work. The tower is 100 ft. high; its diameter at the base is 42 ft., decreasing to 15 ft. at the top. It is solid for 30 ft. at which height the doorway is placed. The interior is divided into six storeys. After five years the building was finished at a cost of £61,300. Since the lighting no wrecks have occurred on the reef. A bust of Stevenson by Samuel Joseph (d. 1850) was placed in the tower.