Physiological telegraph, 1839, J.H. Holtgräve, Deventer
From the Physics and Chemistry Society, Deventer
Inv V08005

Around 1840 Europe was a buzz with rumours about the possibility of transmitting messages over great distances with electricity. Everyone with expert knowledge applied their minds to it. Pieter Vorsselman de Heer from Deventer was no exception. He worked out that it was more favourable to put the telegraph wire under charge than to pass a current through it. And in 1839 he devised a transmitter and a receiver. When a key on the transmitter was pressed, the corresponding key on the receiver became live. And because the telegraph operator had his fingers on the keys, he could feel from the tingling in his fingers what keys were being depressed. In this way the message could be transmitted by ‘piano playing’. There was only one problem: the receiving telegraph operator did not have his hands free to write down the message.