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Function It produces sounds tuned one with the other. |
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Description Also this apparatus is an accessory of the rotary apparatus. It is formed by four brass disks with pointed isosceles gear teeth in numbers of 80, 60, 50, 40, fitted on the same axe that ends with a cone. If the wheels rotate with a uniform motion, by drawing a thin cardboard near the gear teeth, we have vibrations proportional to the numbers 8, 6, 5, 4 and the corresponding sounds are perfectly tuned. | |||
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| Another slightly different siren Pellegrini (2) |
 (1)
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Function If the speed of rotation is constant we obtain a perfect tune between the emitted sounds. | |||
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Description (1) If is formed by a disk of aluminium with a set of four holes in number of 80, 60, 50, 40, corresponding to the perfect tune. After applying the siren to the axe of the rotary apparatus, we make it to rotate with constant speed, and we aim a powerful flow of air at the holes. (2) Disk with a set of height holes. | |||
