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oil. The damping may be reduced or entirely removed so that high harmonics may be shown.

The ingenious principle on which this instrument is founded

is shown in the diagram. (Fig. 33.)

Fig. 33.

Two thin wires of about 7 ohms each are traversed by a current of about 0'4 ampere from a battery B through equal resistances Rr Superposed on this current, an alternating current of about 0'3 ampere passes from C to F, so as to reduce the current in one side and increase it in the other. By putting a tension on the wires at their centre, in a direction normal to their length, the differential extension of the wires due to temperature change produces a deflection of a small mirror fixed to the centres of the two wires. The wires are immersed nearly up to the mirror in oil.

The special feature of the instrument is the condenser K and the resistance R4 in the circuit. These compensate for the thermal lag in the instrument.

Another resistance, R5, governs the damping, and is variable or removable.

The outfit consists of—

A double oscillograph, indicating simultaneously two wave forms.

A condenser and resistance, K’ R4, suitable for 250 volts.

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Le texte affiché peut comporter un certain nombre d'erreurs. En effet, le mode texte de ce document a été généré de façon automatique par un programme de reconnaissance optique de caractères (OCR). Le taux de reconnaissance estimé pour cette page est de 99,05 %.

La langue de reconnaissance de l'OCR est l'Anglais.

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