Page:Mind (Old Series) Volume 11.djvu/227

 226 J. M. CATTELL funnel, and covered with kid leather. When the observer speaks into the mouth-piece, the sound waves through the membrane into vibration, and the platinum contact at c is broken ; the breath accompanying speech also breaks the contact. The current making the electromagnet (Fig. 7) FIG. 5. FIG. 6. FIG. 7. Hows through this contact ; so when it is lm-kcii, if only for an instant, the soft iron looses its magnetism, and the armature is drawn back by means of the spring F. Tin 1 strength of this spring can be regulated by means of the screw N. The binding screws B B' are connected respectively with