Bob laughed.  "Why, don't you recognize the products of your talented son, dad?" he cried, as he took the object down and clapped it over his father's iron-gray head.  "That's my new wireless telephone headpiece, and right underneath it here is the mahogany cabinet containing the sending and receiving instruments.  You see, these two wires run from the plug up to the receivers, there being one receiver in each side of the helmet, right over your ear, pressing against the ear tightly by means of a sponge-rubber gasket."