COMPOUND MOTION. 



81 



Fig. 54, 



the hydro-extractor (water-extractor), Fig. 53. The machine consists of a 

 large hollow wheel, or cylinder, A A, turning upon an axis, B. The eidca 

 and bottom of the wheel are pierced with holes like a 

 sieve. The wet cloths being in and around the sides, 

 A, the wheel is caused to revolve with great rapidity, and 

 the water contained in the material, by the action of tho 

 Centrifugal Force^ flies out, and escapes through tho 

 apertures left in the sides of the wheel A rotation 

 of 1500 times per minute, is sufficient to almost en- 

 tirely dry the cloth, no matter how wet it may have been 

 originally. 



When a bucket of water, attached to a string, is 

 whirled rapidly round, the water does not fall out when 

 the mouth is presented downward, since the Centrifugal 

 Force imparted to the water by rotation, tends to causo 

 it to fly oflF from the center, and this overcomes, or bal- 

 ances, the attraction of gravitation, which tends to causo 

 the water to fall out, or toward the center. Thus, in 

 Fig 54, the water contained in the bucket which is up- 

 side down, has no support under it, and if the bucket 

 were kept still in its inverted position for a single mo- 

 ment the water would fall out by its own weight, or, in 

 other words, by the attraction of gravitation, which rep- 

 resents a Centripetal Force ; but tho Centrifugal Force, 

 which is caused by the whirling of the bucket in the di- 

 rection of the arrow, tends to drive the water out through 

 the bottom and side of tho vessel, and as this last forco 

 overcomes, or balances the other, the water retains its 

 place, and not a drop is spilled. 



When a carriage is moved rapidly round a comer, it is 

 yery liable to be overturned by the Centriftigal Forco 

 called into action. The inertia carries the body of tho 

 vehicle forward in the same line of direction, while tho 

 wheels are suddenly pulled around by the horses into a 

 new one. Thus a loaded stage running south, and sud- 

 denly turned to the east, throws out the luggage and 

 passengers on the south side of the road. When railways form a rapid curve, 

 the outer rail is laid higher than the inner, in order to counteract the Centri- 

 fugal Force. 



' An animal, or man, turning a corner rapidly, leans in toward the comer or 

 center of the curve in which he is moving, in order to resist the action of 

 the Centrifugal Force, which tends to throw him away from the center. 



In all equestrian feats exhibited in the circus, it will be observed that not 

 only the horse, but the rider, inclines liis body toward the center. Fig. 55, and 

 according as the speed of the horse round the ring is increased, this inclina- 

 tion becomes more considerable. When the horse walks slowly round a large 



