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Sound and Music: Sounds

All sound appears to be echo or reflection; and if not a distinct echo, it is only for want of distance. In a real echo, the first sound is from near surfaces; the second, or echo, from the distant surface. Sounds, in liquids and solids, are more efficient and more rapid than in air. Two stones, rubbed in water, may be heard in water at half a mile. Cast-iron conducts sound with ten and a half times the velocity of air. A string, or piece of deal, held to the ear, or between the teeth, gives a vast increase of effect. And pipes convey sounds to vast distances. Sound is lost in passing from one medium to another, and hence, as we produce sounds by vibrating solids, the effect in the air is less. Sounds are distinct at twice the distance on water that they are on land.

MECHANICS.

Mechanics are the practical economy of Motion and Matter, and they consist of various contrivances, to vary momentum by varying the velocity or impulse. They are also made to vary the directions of the motion, so as to produce particular effects. Power is gained by increasing the velocity of the acting force, and when speed is required in the work, by diminishing the velocity of that force: for power at one end of a machine into its velocity, is always equal to velocity and power at the other end; and there is no exception to this law, except in the allowance to be made for friction and resistance, from one-third to one-fifth. The principal contrivances for conveying the power of a machine to the work, are Wheels and pinions on axles.