48 
THE FIRST TELEPHONE. 
It is carved in oak-wood. Of the tympanic membrane only small 
fragments now exist. Against the centre of the tympanum 
rested the lower end of a little curved lever of platinum wire, 
which represented the “ hammer ” bone of the human ear. This 
curved lever was attached to the membrane by a minute drop of 
sealing-wax, so that it moved in correspondence with every 
movement of the tympanum. It was pivotted near its centre by 
being soldered to a short cross-wire serving as an axis. The 
upper end of the curved lever rested in loose-contact against the 
upper end of a vertical spring, about one inch long, bearing at 
its summit a slender and resilient strip of platinum foil (see 
Fig. 4). An adjusting screw served to regulate the degree of 
contact between the vertical spring and the curved lever. 
Conducting wires by means of which the current of electricity 
entered and left the apparatus were affixed to screws in con- 
