Cups and string. Engraving of a man and woman using a simple telephone system comprised of two cups and a length of string. When one person speaks into a cup,the notes in the voice will cause pressure waves in the air. If the string is held taut,these pressure waves will be transmitted along the string to the other cup. Another person can then hear the first person's voice. Image from the 19th century | |
Licence : | Droits gérés |
Crédit: | Science Photo Library |
Taille de l’image : | 4606 px × 4077 px |
Model Release : | Non requis |
Property Release : | Non requis |
Restrictions : | - |