Ericson telephone handset, c 1920s.
© Science Museum / Science & Society Picture Library
This sectioned handset shows both the earpiece and mouthpiece of a 1920s Ericson telephone. Within the earpiece, two wire coils combine to vary the field of the permanent magnet. An iron diaphragm lies beneath the magnet, and allows the soundwaves to be heard. Inside the mouthpiece, a perforated screen protects the diaphragm while still allowing soundwaves to pas through. The Ericson company was founded by Lars Magnus Ericson (1846-1926), a Swedish telegraph instrument repairer. After Bell invented the first telephone in 1876, people brought their phones to be repaired and his firm began producing their own phones. By the early 20th century, the busines had expanded into Europe and the United States. Today, Ericson has facilities in over 140 countries worldwide.