The typical telegraph galvanometer from Ericsson. 7

A didactical coherer receiver with bell. 4

View of the coherer/decoherer. 4

A single needle block telegraph. 4

A double needle block telegraph. 3

The Batavia (now Jakarta)-Singapore cable from 1859. 8

A variable resistance for telegraph measurements. 1

A big Wheatstone bridge by Siemens & Halske. 8

A very early high voltage dry-cell battery by Zamboni. 3