21 Electrical Sound-Amplifying Devices, Loud-Speaking Telephones, Marine Telephones, Aircraft-Telephones,[ Desk-Telephones,] Audion-Frequency-Amplifying Cabinets, Control-Boxes for Loud-Speaking TelephONes, Loud-Speaking Transmitters, JunctiON-Boxes, Antinoise-Telephones[, and MaSTEr-Ringers for Marine-Telephone EquipmENT]