BLOWING MACHINES 



779 



BLUBBER 



quickly into maggots, which destroy the meat. 

 In some places these flies and maggots play an 

 important and useful part in quickly disposing 

 of carrion, but in the house they are a menace, 

 carrying germs of disease and spreading infec- 

 tion. Great care should be taken to keep all 

 food beyond their reach, and garbage cans, 

 their favorite breeding places, should be se- 

 curely covered. The blowfly breeds so quickly 

 that the offspring of one fly may number many 

 thousands in a few days. 



BLOWING MACHINES, a name given to 

 various devices which are used to produce, 

 supply and direct a strong artificial current of 

 air under pressure. One of the oldest, simplest 

 and most common of blowing machines is the 

 bellows (which see), which has been used by 

 blacksmiths and workers of metals since time 

 immemorial. Blowing machines are of several 

 kinds, according to the uses to which they are 

 put. Some are used to produce a forced 

 draught in order to assist the burning of fire 

 in boilers and furnaces; others for ventilating 

 purposes, that is, for extracting the foul air 

 from buildings, mines or ships and forcing in 

 pure air; while other big special machines are 

 employed for supplying air to blast furnaces 

 and in the Bessemer process for manufacturing 

 steel. The chief varieties of blowing machines 

 are known as disk blowers, fan blowers and jet 

 blowers. 



Disk Blower. This consists of an axle which 

 has attached to it several blades so arranged 

 together as to form a rimless wheel, which is 

 enclosed and moves within a cylindrical casing 

 open at both ends. The ordinary electric fan 

 used in offices and homes, which is a form 

 of disk blower, gives a good idea of the form 

 of this wheel and the way it rotates. As this 

 machine is used for ventilating purposes, it is 

 usually set in the wall of the building, with 

 one opening of the cylindrical casing towards 

 the building and the other to the outside air. 

 The axle and blades are rotated by means of 

 an electric motor, and according to the way 

 the machine is set it either sucks the foul air 

 from the building or forces fresh air into it. 



Fan Blower. The fan blower is the most 

 common of modern blowing machines. It is 

 like the disk blower, except that the axle of 

 the fan blowers is provided with radial spokes, 

 as in a rimless wheel, to the ends of which are 

 fastened blades arranged parallel with the axis. 

 This wheel is situated inside of a circular casing 

 of steel or cast iron, within which it is made 

 to revolve rapidly. When this wheel revolves 



it causes the air within the casing to revolve 

 also. In this way a centrifugal action is set up 

 by which there is a diminution of pressure at 

 the center of the machine and an increase of 

 pressure against the sides of the casing. The 

 air is then sucked in through circular orifices 

 at the central side of the casing and is forced 

 out through an outlet in the side called the 

 delivery tube. 



Jet Blower. Another kind of blower in 

 common use is the jet blower, in which a jet 

 of steam is used to produce a current of air. 

 The principle upon which it is based is the 

 following: When a jet of steam is allowed to 

 escape through a small opening or through a 

 tube of small diameter which is inserted into 

 a larger tube open at both ends, it creates a 

 current of air. The air is pushed in the direc- 

 tion of the escaping jet and a fresh supply is 

 drawn in through the other opening, so that 

 a continuous stream of air passes along the 

 tube. The exhaust nozzles used in the smoke- 

 stacks of locomotives and fire engines are ex- 

 amples of jet blowers. os. 



BLOWPIPE, a small tapering tube used to 

 direct a current of air upon the flame of a 

 lamp, candle or gas jet, forcing it in any desired 

 direction and causing it to burn very rapidly, 

 thus intensifying its heat. In its simplest form 

 the blowpipe consists of a funnel-shaped tube 

 of brass or glass, usually seven inches long and 

 one-half inch in diameter at the larger end 

 and tapering so as to have a very small open- 

 ing at the lower end. Within about two inches 

 of the smaller end the pipe is bent nearly to 

 a right angle, so that the fine current of air 

 may be directed sidewise to the operator. 



The current of air may be produced by a 

 bellows instead of the breath. The blowpipe 

 is used by jewelers for soldering, and by glass- 

 blowers in making thermometers. See BLOW- 

 ING MACHINES. 



BLUBBER, blub' er, the fatty strip which 

 lies just beneath the skin of whales and other 

 warm-blooded sea animals, furnishing a protec- 

 tion against the cold. When refined it yields 

 oils for lubrication, fuel and soapmaking. 

 Whale oil was extensively used in lamps until 

 petroleum was discovered, but it is now em- 

 ployed in such a manner only by the Eskimos. 

 Blubber is an important part of Eskimo diet, 

 and is also eaten by the Ainos and other inhabi- 

 tants of northern Japanese territory. Whalers 

 remove blubber from the body of the animal 

 in large strips by means of spades and shovels, 

 and secure two or three tons from every catch. 



