Fifth book of lessons for the use of schools . ell, which is to be raised by winding the rope, towhich it is attached, roundthe axle; if this be donewithout a wheel to. turn theaxle, no mechanical assist-ance is received. The axlewithout . a wheel is as im-potent as a single fixed pul-ley, or lever, whose fulcrumis in the centre; but addthe wheel to the axle, and• you will immediately find thebucket is raised with muchless difficulty. The axle actsthe part of the shorter arm of the lever, the wheel thatof the longer arm. The velocity of the circumferenceof the wheel is as much greater than tha
Fifth book of lessons for the use of schools . ell, which is to be raised by winding the rope, towhich it is attached, roundthe axle; if this be donewithout a wheel to. turn theaxle, no mechanical assist-ance is received. The axlewithout . a wheel is as im-potent as a single fixed pul-ley, or lever, whose fulcrumis in the centre; but addthe wheel to the axle, and• you will immediately find thebucket is raised with muchless difficulty. The axle actsthe part of the shorter arm of the lever, the wheel thatof the longer arm. The velocity of the circumferenceof the wheel is as much greater than that of the axie,as it is further from the centre of motion; for thewheel describes a large circle in the same space of timethat the axle describes a small one, therefore the poweris increased in the same proportion as the circumferenceof the wheel is greater than that of the axle. If thevelocity of the wheel were twelve times greater thanthat of the axle, a power nearly twelve times less thanthe weight of the bucket would be able to raise THE INCLINED PLANE. The fourth mechanical power is the inclined is nothing more than a slope, or declivity, fre-quently used to facilitate the drawing up of is not difficult to understand, that a weight may withmuch greater ease be drawn up a slope than it can be- MECHANICAL POWERS.—THE WEDGE. 285 Kilted the same height perpendicularly. But in this, aswell as the other mechanical powers, the facility is pur-chased by the loss of time; for the weight, instead ofmoving directly from A to c, must move from B to C,and as the height of the plane is to its length, so is the
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